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What Is GNSS Satellite Technology Used For

GNSS is short for ‘Global Navigation Satellite System.

The system consists of a number of space satellites, which transmit positioning and timing data.

The data is then received by GNSS receivers, located on earth.

The receivers use the data received from the satellites, to determine the receivers location on earth.

GNSS systems provide global coverage, and a number of separate  countries have their own developed systems.

Examples of systems that have been developed by countries include Europe’s ‘GALILEO’ , Russia’s ‘GLONAS’ , and the United States ‘NAVSTAR’.

Performance Considerations

To assess the performance of a system, the following bench – marking criteria are used.

1) Accuracy

2) Integrity

3) Continuity

4) Availability

 

 

 

 

 

 

 

 

 

 

 

Featured

Things Network Gateway Diy Build

What is the Things Network

The Things Network originated in Amsterdam, Netherlands in 2015.

The idea was to create a crowd funded Internet of Things network, that was open to the public.

The network uses LoraWAN spread spectrum wireless technology to enable data from environmental sensors, to get onto the Internet.

The network has quickly expanded through crowd funding and volunteers installing their own ‘Gateway’ devices.

The Gateway devices receive data that has been transmitted from sensors, and puts that data onto the Internet cloud.

Sensors can include pollution monitoring devices, Smart Parking detectors, flood warning sensors etc.

The LoraWAN that I mentioned is the wireless technology that allows the transfer of data from the sensor (which might be in a field a mile from the Gateway), to the receiving Gateway device.

LoraWAN Characteristics

Lorawan is suitable for applications that only require small amounts of data to be transferred at a time. Therefore LoraWAN would not be suitable for transmitting video from a CCTV camera (WIFI would be more suitable).

Data transfer is also quite slow.

What LoraWAN excels at is allowing small amounts of data to be sent over relatively long distances (such as 10Km), while consuming very low battery power.

The good communications range, and low battery power consumption make it ideal for the Internet of Things, or IOT for short.

To start using the Things Network, there are a few options available.

Firstly you can buy a ready made indoor Gateway that the initiators of the Things Network have now manufactured.

A second option is to buy a Gateway designed for commerical LoraWAN use. These Gateways are often designed for outdoor use, and feature weatherproof construction.

A third option to get onto the Things Network, if there is no local Gateway within range, is to build your own Gateway.

There are a few options and ways to build a Gateway, including using an RF board from RAK Wireless.

The option that I used to build my Gateway, uses an 880A LoraWAN Concentrator board from IMST of Germany.

The RF Concentrator board is controlled and connected to the Internet via a Raspberry Pi.

Full details for construction are given below.

Building the Gateway

For beginners to building their own gateway, I would recommend joining, or founding a local Things Network .

The Lorawan Gateway that I am going to describe here, is designed to operate on the Things Network, however other lora networks can easily be installed.

The main components that you will need are:-

1) A Concentrator board from IMST of Germany. The Concentrator board is the wireless communications part of the system, responsible for receiving the wireless data signals, from the remote environmental sensors (Air quality sensors etc).

2) A small computer to store the software that controls the Concentrator board. We are going to use the UK designed Raspberry PI 3.

A Micro SD Card, for holding the software used by the Raspberry PI.  A small 4 GB card is fine.

3) A suitable Antenna (or Aerial), with pigtail connecting cable.

4) A suitable 2 Amp rated power supply, with a micro USB connector.

5)  7 Female to Female connecting leads, suitable for raspberry PI.

4) A suitable case, to house the components.

The first thing I need to make you aware of is the risk of static electricity, to your IMST ic880a Concentrator and Raspberry PI.

Static can damage the sensitive electronic components, therefore it is advisable to take precautions, such as not touching the board components, and wearing an anti static wrist strap.

The first thing you need to do is to format the micro SD card, that will be fitted to the raspberry PI, to hold the gateway software.

The SD card association has a free piece of software, for Windows PC and Mac, to do this. My card was already formatted, so I skipped this step.

The next step is to burn the actual software that will power your gateway, onto the Raspberry PI.

To do this, I used https://etcher.io/    

I first installed Etcher onto my  linux desktop computer. As most people use Windows PC, or Mac, you will need to find a suitable alternative to Etcher.

I also downloaded the operating system needed to run the Raspberry Pi, which is called Raspbian Stretch Lite , onto my desktop PC.

Put your micro SD card into your computers micro SD card reader. If your computer (like mine) does not have a card reader, then external USB plug in ones can be purchased cheaply (I got mine from my local Asda supermarket for £6).

Fire up Etcher, or whatever card  burning software you prefer, and select the copy of Raspbian Stretch Lite , that you previously downloaded to your PC.

Follow the instructions, and burn the operating system software onto the micro SD card.

Once you have successfully burned your Raspbian Stretch Lite, onto your SD card, insert it into the Raspberry Pi (the slot is on the underside of the Pi).

The next thing to do is to connect your Raspberry Pi to a suitable monitor (I used a TV, that had a HDMI connection), and also connect a USB keyboard, power supply, and mouse.

The power supply should be 5 Volts DC, and Raspberry Pi power supplies are widely available. I used a USB phone charger, with 5 Volts output, and a current rating of 2000mA.

Boot up your Raspberry Pi (connect the power), and you will see lots of computer code scrolling across your screen (if you have done everything successfully, so far).

When the Raspberry Pi asks you for a user name and password, use the following default ones (the  bit after the  ‘ : ‘ ).

Username: Pi

Password: Raspberry

After you have successfully logged in, type:

 sudo raspi-config

Numbered options will now hopefully be on your monitor screen.

Select [5] Interfacing Options, and then P4 SPI

Then select [7] Advanced Options , and then [A1] Expand Filesystem.

You now need to exit the raspi-config utility, either by hitting the ‘CTRL’  and  ‘X’ keys, or by typing sudo reboot

Next you are going to Configure the locales and time zone.

Type this in, to set the locales, and follow instruction.

sudo dpkg-reconfigure locales

Next, type this in to set time zone.

sudo dpkg-reconfigure tzdata

The next stage is to update the raspberry Pi software, do this by typing:

sudo apt-get update

Then install any upgrades to the operating system software, by typing sudo apt-get upgrade

Next we are going to install Git , which is needed to be able to download the Things Network software from Github.

Type:

sudo apt-get install git

The next step is to create a user called TTN (the things network).  This user will eventually replace the default raspberry pi user, which we will delete.

sudo adduser ttn

Then:    sudo adduser ttn sudo

Logout, by typing logout

Once you have logged out, log back in using the user name and password that you have just set up, when you added a user.

You can now delete the default Raspberry Pi user, by typing

sudo userdel -rf pi

Set the WIFI  SSID and password details, which can be found on the back of your home router / Hub (usually).

To set the WIFI details type

sudo nano /etc/wpa_supplicant/wpa_supplicant.conf 

Once you have typed in the above text, you should see some code on the screen. Add the following to the end of the existing code, making sure that you enter your SSID and password details, in place of the shown text.

network=

{
ssid="The_SSID_of_your_wifi"
psk="Your_wifi_password"

}

Now we are going to clone the installer from Github. This will download the software which runs the gateway, from the Github repository.  Type each of the following three code lines into your Pi, one at a time, hitting the return key after each line of code.

  git clone -b spi https://github.com/ttn-zh/ic880a-gateway.git ~/ic880a-gateway
  cd ~/ic880a-gateway
  sudo ./install.sh spi

Identifying the LoraWAN Gateway

The software will give the gateway the default name of ttn-gateway.

This however may need to be changed, to prevent issues with other Things Network Gateways within wireless range.

Wiring it Up

The next step is to connect the  Concentrator board, to the Raspberry Pi, and also connect the antenna.

The components including the antenna should be mounted in a protective box,  and the antenna connected to the Concentrator board.

It is very important that the Concentrator board is not powered up, with no suitable antenna connected, of damage could occur to the board.

Once the antenna is connected, then the next step is to connect the Concentrator to the Raspberry Pi.

Connect using female to female connecting wires, as follows:

iC880a Concentrator pin Description RPi physical pin
21 Supply 5V 2
22 GND 6
13 Reset 22
14 SPI CLK 23
15 MISO 21
16 MOSI 19
17 NSS 24

IMPORTANT DISCLAIMER:

It is important that you identify the correct pins, by referring to the manufactures data sheets (Both IMST & Raspberry Pi).

We accept no liability for loss or damage caused, by following these information only instructions.

For help, and to learn more about the Things Network Gateway, or what the Things Network can do, why not get in touch with me.

@acraigmiles

www.craigmiles.co.uk

Craig Miles (C) 2018 -2019 , all images and content, unless stated separately.

Featured

Preventive Maintenance For Electric Motors

Preventative Maintenance

Preventive maintenance programmes  are the key to reliable, long-life operation of electric motors.
Whilst AC Induction Motors are particularly reliable in service, almost all electrical equipment requires periodic planned inspection and maintenance. Planned preventative maintenance ensures electrical motors, and starters are kept in good working condition at all times. This is critical for businesses that rely on electric motors. A scheduled routine of motor inspection should be carried out throughout the motor’s life. Periodic motor inspection helps prevent serious damage to motors by locating potential problems early.

Periodic Inspections

Planned electric motor maintenance programmes are designed to help prevent breakdowns, rather than having to repair motors after a breakdown. In industrial operations, unscheduled stoppage of production or long repair shutdowns is expensive, and in marine shipping environments, a potential safety issue. Periodic inspections of motors are therefore necessary to ensure best operational reliability.

Preventive maintenance programmes require detailed checks to be effective. All motors onsite (factory, ship etc) should be given their own individual identification (ID) number and have a record log. The record log is usually computerised these days. The motor records kept should identify the motor, brand, inspection dates and descriptions of any repairs previously carried out. By record keeping, the cause of any previous breakdowns can help indicate the cause of any future problems that might occur.

All preventative maintenance programmes should refer to the equipment manufacturer’s technical documentation prior to performing equipment checks.

There are simple routine maintenance checks that can be applied to three phase induction motors, which help ensure a long service life to a motor. 

The Simple checks that can be carried out, include a review of the service history, noise and vibration inspections. Previous noise issues could for example be due to motor single phasing. Previous vibration may have been due to worn bearings, which allow the Stator to turn. Other checks include visual inspections (damage and burning), windings tests (insulation resistance & continuity), brush and commutator maintenance (dc motors) and bearings and lubrication.

Inspection frequency and the degree of inspection detail may vary depending on such factors as the critical nature of the motor, it’s function and the motor’s operating environment. An inspection schedule, therefore, must be flexible and adapted to the needs of each industrial or marine environment.

(c) Craig Miles 2019.  craigmiles.co.uk

For bespoke electrical training with Craig, call  +44 (01522) 740818

Featured

Induction Motor Servicing Tips For Ships & Factories

Induction Motor Servicing.

Induction motors are used widely in factories and on ships.

They are very reliable machines, but faults can develop over time.

That is why you need Induction motor servicing to be carried out.

Potential faults include burnt out Stator windings, worn bearings, and water damage which causes low insulation resistance.

This article covers tips on Induction motor servicing.

Safety & Isolation of supply of induction motors.

Correct electricity supply isolation procedures are critical for safety.

Taking a casual approach to electrical supply isolation can prove fatal.

Three phase Induction motors, typically operate in factories at around 400 Volts AC (Alternating Current).

Marine installations typically operate at an even higher 440 Volt Alternating Current (440 VAC).

It is important that no one works on a piece of three-phase machinery, such as an Induction motor unless you are qualified to do so.

On board ship, proper authorisation, such as a valid ‘permit to work’, signed off by a ships chief engineer, should be in place before carrying out any Induction Motor servicing.

On land seek authorisation from the responsible senior managers, with appropriate responsibilities for safety.

For work to be carried out aboard Ships, permission from someone such as the Chief Engineer is appropriate.

Once permission has been gained, and the appropriate paperwork issued, only then can work commence.

Certainly in the marine environment, and normally onshore as well, ‘locks and tags’ will be issued.

The lock is to ensure that once an isolator switch has been turned off, no one can switch it back on accidentally.

The ‘tag’ details who has isolated the supply, and is working on that circuit.

Only the person who has been issued with the lock and tag set, can remove them.

Double check that circuit is dead.

Don’t assume that just because you have locked and tagged the appropriate electrical isolator, that you are safe to work on a circuit.

The isolator may be incorrectly labeled, or even worse, you have taken someone else’s word for it.

Before you stick your fingers in, and potentially kill yourself, you need to use an appropriate device to check that the circuit is safe to work on.

Induction motor servicing can be dangerous, if proper procedures are not followed.

There are three possible devices that can be used:

  1. Test Bulb
  2. Multimeter / Voltmeter
  3. Line Tester

Firstly lets look at the test bulb as an option.

A test bulb with appropriate leads and clips attached, can provide indication of a live circuit, but has a flaw.

If the bulb filament breaks, then you could falsely assume that the circuit is safe to work on, with possibly fatal outcomes.

The second option is the Multimeter / Voltmeter which these days will probably be a ‘solid state’ digital type, rather than the older analogue types, which are commonly referred to as ‘AVO’s’ in the UK.

The Multimeter / Voltmeter being ‘solid state’ is more likely to be a bit more reliable than, a filament bulb tester. However it still may be broken, and you would not necessarily know. An example being the test probe wires may be ‘Open Circuit’.

The third option, the ‘Line Tester’, will provide the most reliable indication of whether a circuit is safe. Therefore this is the preferred option.

The reason that a line tester is safer is because it contains four separate Neon bulbs (some modern ones are LED).

The bulbs light up according to how high the voltage is, for example a 400 VAC supply would light not only the 400VAC light, but the lower voltage indicator lights as well.

So imagine that the 400VAC indicator bulb has broken.

The lower voltage indicator bulbs will still light up, for example the 230VAC and 110VAC indicator bulbs.

Therefore the engineer will still have an indication that there is voltage in the circuit, and can investigate further.

Before using a Line Tester you should use a ‘proving unit’. A proving unit is a small hand-held device capable of producing a voltage such as 250 Volts.

The Line tester can thus be tested using the proving unit, prior to testing a real live circuit.

To test the Line Tester the two probes are pushed against the Proving Unit which then produces a voltage.

This will be indicated by an indicator LED lighting up on the proving unit itself.

The Neon or Led indicator lamps of the Line Tester should also light up at the same time, to indicate the voltage being supplied.

Tips when changing bearings on Induction Motors

Bearings on Rotor

The bearings on an induction motor, allow the ‘Rotor’ to rotate inside the ‘Stator’ which surrounds it.

Over time they can become worn, which may increase noise and vibration of the motor.

Bearings are not usually adjustable, so replacement is required.

 

Importance of  Bearing identification code facing outwards.

When refitting bearings to an induction motor you will notice that the bearing itself has a code written on the one side of it.

This code is the product identification code, and is what you need to quote in order to order the correct replacement bearing.

Once the correct replacement bearing has been obtained, and is ready for fitting, ensure the following.

Firstly, that the bearing identification code is facing away from the Stator, and outwards towards the end of the motor shaft.

This will help you in the future, if you ever have to replace the bearings again.

The reason for this is that you can just remove the end plate of the induction motor, and read the bearing code easily, provided it has been fitted with the code facing outwards.

If the bearing code was facing inwards, then it is harder to read the bearing code, and might mean that the motor shaft has to be disconnected from its mechanical load.

This adds to the motor downtime, and hence has financial and productivity implications.

 

Ways to remove bearings from induction motor shaft.

The ideal way to remove an old bearing from the induction motor rotor shaft is to use a bearing puller tool.

Removal is then just a matter of fitting, the tool into position, and winding in the screw thread in a clockwise direction.

As this happens, the bearing is slowly pulled up and off the shaft.

If however you don’t have a puller, other methods, such as  using a metal bar to leverage between the bearing and the end of the shaft can be tried.

However this is not the way I recommend, and you do it at you own risk of injury and damage to the motor shaft.

 

Methods for fitting a new induction motor bearing.

Ideally you will have a hydraulic bench press, that you can use to put massive pressure down onto the bearing to ‘press it’ onto the shaft, in the correct position.

When using such a press, a number of precautions should be observed.

Firstly, ensure that you are fully competent to use the hydraulic press. Even fairly cheap versions are capable of exerting many tons of pressure, which can be dangerous to human health.

Secondly, ensure that the tube or sleeve that you fit over the shaft of the motor is only just wide enough.

The reason for this is that a wide metal tube (or sleeve) put over the motor shaft in order to push against the bearing, can damage it.

This is because too wide a tube will make contact with the plastic middle of the bearing, or the outer metal edge.

Both of these two scenarios are bad, because pressure applied to anywhere but the centre metal part of the bearing, will cause damage.

This damage can result in the replacement bearing being ruined, which defeats the object of replacing it.

Using a hydraulic press is the method that we would recommend, however this option is sometimes not available.

In particular to engineers working at sea in a marine environment, such as a cargo ship.

If you find yourself in this situation, then there are other ways to re-fit a replacement bearing to an induction motor.

One method is to take advantage of the fact that metals contract and expand due to cold and heat.

This method involves carefully wrapping up the Stator part of the induction motor in a polythene bag, and putting it in the freezer overnight.

This will very slightly shrink the size diameter of the bearing shaft.

The second part to the operation involves gently heating up a pan of engine oil, so that it is warm.

Obviously extreme care needs to be taken, so that either a fire is not caused by the oil igniting, or the engineer receiving burns while trying to handle the hot bearing.

Once the bearing is warm, the Stator can be removed from the freezer, and the warm oiled bearing should slip fairly easily onto the shaft.

The oil can then be wiped off the bearing with a non fluffy cloth, and motor reassembly can begin.

 

 

 

Featured

Electric Morris Minor

This blog post is about my design suggestions for an electric Morris Minor.

There have already been some prototype electric Morris Minor conversions already, which I will discuss.

In addition I have designed alternative ways to successfully convert classic cars such as the Morris Minor.

History & background

The Morris Minor is a British car designed by Sir Alec Issigonis, that was launched in 1948.

The Morris Minor originally was produced with an 918cc Side valve Petrol engine, but this was replaced in the early 1950s by an Overhead Valve (OHV) engine.

The OHV engine was improved and its size increased during the remainder of its production. and the later models were 1098cc in cubic capacity size.

The standard Morris Minor had the engine connected to a four speed longitudinal mounted gearbox, attached at the back of the engine.

The gearbox output is connected to a long single drive shaft, which runs underneath the car.

The drive shaft connects the gearbox to the rear axle.

The rear axle incorporates a ‘differential’ which fixes the speed ratio, between the rotational speed of the drive shaft, and the rotational speed of the road wheels.

Therefore as the engine power is transferred via the gearbox and drive shaft, to the rear axle, it is a rear wheel drive car.

Any design for an electric Morris Minor, will probably stick with the rear wheel drive configuration.

The reason for keeping the electric Morris Minor as Rear Wheel Drive, or RHD for short, is engineering design simplicity.

The front suspension on a Morris Minor was advanced for a British car of its time (1948).

The front suspension used torsion bars, as the springs, and featured ‘rack and pinion’ suspension, that is still used in modern cars.

The shock absorbers are different to the type used in modern cars, and are known as ‘lever arm shock absorbers’.

To convert an electric Morris Minor into powering the front wheels, known as front wheel drive, would require major suspension modifications (unless hub motors were used).

This is because the original Morris Minor steering and front suspension system, would need a lot of component changes.

Of course its possible to make a front wheel drive Morris Minor, but more expensive, and also changes the cars handling characteristics.

If however you are hell bent on a front wheel drive electric Morris Minor then its possible.

My solution would be to use hub integrated motors.

Hub integrated motors consist of an individual electric motor powering each driving wheel.

For instance to create a front wheel drive Morris Minor, you would have two motors driving each of the two front wheels.

If you wanted to use hub motors, but to keep the traditional Morris Minor rear wheel drive configuration, you would fit the motors to the two rear wheels.

So let’s decide to stick to the original rear wheel drive layout for our electric Morris Minor.

There are four ways that you could configure the electric motor layout. This also applies to many other classic cars, which share the same basic layout.

Firstly, the original internal combustion engine can be removed, whilst leaving the Morris Minor gearbox, driveshaft and rear axle (Inc differential) in place.

An electric motor is then attached to the original Morris Minor gearbox.

Some electric motor conversions that use this layout configuration, are clutch less in design. The torque & high rev range of many electric motors mean that the car can be driven in the same gear for most of the time.

Other electric car conversion designs still incorporate a conventional clutch.

The advantages of retaining a clutch are better motor speed control, and more importantly more retention of the original Classic Car experience.

A second option for mounting the electric motor in your Morris Minor, would be by removing the gearbox and either mounting the electric motor at the front end of the drive shaft, and directly attached to its front end.

Or alternatively the drive shaft could be removed, and the motor mounted directly to the rear axle differential input shaft.

This second method of attaching the electric motor directly to the rear axle differential connection, has advantages and disadvantages.

The advantage is a saving of weight, by removing the drive shaft which runs underneath the car, from front to back.

Less weight is a good thing for performance of your electric car.

The disadvantage is that it makes it a bit harder to mount, than if you mounted the electric motor at the front end, and retained the driveshaft.

It is harder to mount, because you need to create a mounting cradle which attaches to the rear axle, and supports the weight of the electric motor.

Morris Minor Hybrid


You may well of heard of Hybrid cars.

If not, then let me explain what they are.

A hybrid car is a car that uses a combination of combustible fuel, such as petrol or diesel, and electric power.

A hybrid car might drive the wheels using an electric motor at low town speeds, and petrol at higher speeds.

Alternatively, the petrol (or diesel) motor could be used, if the battery was low on charge.

The use of electric motors at low speeds around towns, has obvious environmental advantages.

However you might also still want a traditional petrol motor for long distance trips.

My design for a Morris Minor Hybrid, keeps the petrol engine, whilst also adding electric front wheel drive.

The rear wheels continue to be driven by the Morris Minors petrol motor.

Whilst the front wheels are driven by ‘in-hub’ electric motors.

A simple solution would be to have a manual switch, to be able to select the drive system.

Alternatively an automatic electrically controlled system could be used.

I am currently considering the design for an automatic system, and will provide further details in the future.

Gearbox Considerations

If you want design simplicity for your electric Morris, then keep the original gearbox.

The electric motor is simply attached to the gearbox, in place of the original petrol motor.

This is done via a special adapter plate, and a coupler.

The potential problem with using the original gearbox is excess motor torque.

Vehicle Electric Motors produce a lot of torque at low RPM (Revolution Per Minute).

The standard Morris Minor gearbox was designed to handle a maximum engine torque of 60 lb/ft (81 N·m) at 2,500 rpm.

The above torque figure is for the most powerful Morris Minor, built from 1962 onwards.

The gearbox was upgraded in 1962, along with the engine size (to 1098cc from 948cc), and gained Baulk-Ring-Synchromesh .

To ensure that you do not suffer premature gearbox failure, it is important that you consult electric motor manufacturers datasheets.

For an ordinary road going car, this should not be an issue, if precautions are taken to select a suitable motor.

For those looking to upgrade their Morris Minors performance, then this is definitely a consideration.

The characteristics of electric motors is instant maximum torque at very low rpm.

This sudden surge of torque needs to be considered, as it could damage the standard minor gearbox in a relatively short time.

The morris minor has been converted and upgraded for many years by enthusiasts, including the gearbox.

One popular conversion is to fit the Ford Sierra gearbox.

The Ford gearbox offers two advantages.

The first advantage, is that the Sierra gearbox gives you five forward gears, compared with the minors original four.

The second advantage of changing the gearbox to the Ford unit, is strength. The gearbox is stronger, and can handle more power.

Featured

Zigbee Technical Characteristics

Characteristics Overview

Zigbee characteristics make it suitable for short range wireless communications.

It is based on the IEEE 802.15.4-specification, created by the Institute of Electrical and Electronics Engineers (IEEE).

The technology is used to create personal area networks, also known as PAN(s).

PAN’s are created using low-power digital radio tranceivers, using Zigbee technology.

 PAN’s are used in applications including home automation, data collection, and medical devices.

Zigbee is designed to be used in small scale projects requiring wireless connection.

Characteristics of the technology is low-power consumption and RF transmit power, low data transmission rate, and short communication range.

  • Developed by Zigbee Alliance
  • IEEE 802.15.4 based specification
  • High level communication protocols
  • Used to create Personal Area Networks (PAN)
  • Uses small low power digital radios
  • Typically used for home automation, medical device data collection, other projects requiring low power & low bandwidth
  • Conceived in 1995, standardised in 2003, revised in 2006

Features of Zigbee

  • Low power
  • Low data rate
  • Close proximity data communications
  • Wireless ‘ad hoc’ network (WANET), which is a decentralised type of wireless network.

Zigbee Advantages (compared with other WPANS, such as Bluetooth & WIFI)

  • Simpler
  • Less expenditure

Applications (typical uses)

  • Wireless light switches
  • Home energy monitors
  • Traffic management systems
  • Other consumer & industrial equipment, requiring short communication range & low wireless data transmission rate
Typical  Performance
  • 10 – 100 meters range (per device), based on line of sight
  • Range dependent on both power output & environmental characteristics
  • Long distance communication possible by passing data through a ‘mesh network’, which allows the data to transfer through ‘intermediate’ devices between zigbee nodes
  • Long battery life, due to low power consumption
  • Secure communication using 128 bit symmetric encryption keys
  • 250 kbit/s, which is suited to intermittent data transmissions, such as from a sensor or other input device.

Wireless Data Overview

What is 802.15.4 and Zigbee?

IEEE 802.15.4 is a technical standard which defines the operation of low-rate wireless personal area networks (LR-WPANs).

It specifies the physical layer and media access control for LR-WPANs, and is maintained by the IEEE 802.15 working group, which defined the standard back in 2003.

WLAN

WLAN is short for Wireless Local Area Network.

WPAN

WPAN is short for Wireless Personal Area Network.

Zigbee versus Bluetooth & WIFI

For the Internet of Things (IOT) & IIOT (Industrial Internet of Things) the choice of wireless technology, depends on application.

If large amounts of data need to be transmitted between the sensor, and the receiving end, then Wifi may provide the best solution.

An example of an application requiring high data rates is transmitting video images, such as those from a CCTV camera.

WIFI is ideally suited to such an application.

Where WIFI has disadvantages however, is in power consumption and maximum amount of user nodes.

The relatively high power consumption of WIFI, compared with Bluetooth (especially Bluetooth Low Energy), and Zigbee, has issues.

The main issue is that the technology is not well suited to battery powered operation.

If WIFI links are used for data transmission, from remotely located sensors, then regular battery changes are necessary.

Of course if a mains electrical supply is available, then this isn’t an issue.

Bluetooth offers better (lower) power consumption than WIFI, so is a better solution for battery powered equipment.

The disadvantage of Bluetooth is that only 7 connections can be made simultaneously.

The connection time to establish a new connection is also longer in both Bluetooth and WIFI, compared with Zigbee.

Zigbee offers very low power consumption (especially in sleep mode), making it suitable for remote sensors, with long battery lives.

Battery lives can be a few years!

Zigbee is best suited to applications that require small amounts of data to be transmitted at a time.

An example is medical data monitoring of patients, or wireless light switches (Home automation).

Featured

Wet three phase Induction Motor Effects

Flooded or Wet Induction Motors

First of all, try not to!

When designing a marine of industrial installation, you need to consider the IP, or ingress protection rating of your Induction motor.

By choosing a motor with a high enough IP rating, it is possible that when you submerge your Induction Motor, nothing will happen.

This is because the higher the IP rating,  the better the motor casing is at keeping out dust & moisture, from the motors delicate ‘internals’.

Lets imagine a scenario, that an incompetant person has decided to save a few ‘quid’ by specifying an IP54 rated Induction Motor.

This motor will withstand dust & a splash of water, but not submersion, and is therefore suited to dry factories on land, but not a typical marine environment.

So what would actually happen if it gets submerged?

Inside the induction motor are tightly wound coils of copper wire, called a ‘stator’.

It is important for the motor to work, that there is a high ‘Insulation Resistance’ between each of the three ‘Stator Windings’.

Despite being wound tightly together, the stator windings are in fact insulated from each other by the coating on the copper wires.

What happens if water gets into the stator windings, is that the ‘insulation resistance’ between the three separate windings that make up the stator, goes down to very low levels.

The insulation resistance between the ‘phases’ can be measured using an insulation resistance, or IR tester.

Insulation Resistance (IR) testers, often refered to as ‘Meggers’ after a famous brand of IR testers, inject a high voltage through two separate stator windings, or  between a winding and the casing of the Induction Motor.

The display on the IR tester shows the resistance between the separate stator windings.

The insulation resistance should be very HIGH.

On ships, SOLAS (Marine regs) specifies a legal minimum of 0.5 Mega Ohms.

In practical terms you should not accept an Insulation resistance of less than 1M (Mega) Ohm on board ships, and not less than 2M Ohms for land based installations.

Low IR on board ships will cause an Earth Fault alarm to be triggered.

Induction motor servicing tips. Photos (c) Craig Miles 2017-2020.

How to Dry Out a Flooded Induction Motor on-Board Ship.

If you find yourself in the situation of having a flooded motor, with resulting very low insulation resistance, the situation can be remedied.

Firstly consider safety, as water and electricity are not a good combination, and water can conduct electricity.

Follow all correct electrical supply isolation procedures (Valid Permit to work, Locks & Tags etc).

Check and re-check that you have correctly isolated the supply,  using an appropriate tester, such as a ‘live line tester’. Also check that the tester works (using ‘Proving Unit, or known test supply) , both before, and after testing the isolated supply.

Once you are satisfied that the motor is safe to work on, then drying out the stator windings of the flooded motor, can be done in two ways.

The first method is to dismantle the Induction Motor, so that the stator windings are exposed, and to place the motor in a warm environment.

As getting the motor back in service quickly is important, a warm air source, such as a hairdryer can be used to warm the windings, and chase out moisture.

If using something like a hairdryer be careful, as hairdryers have a low IP rating, as they are not designed to come into contact with water.

Therefore keep it at a safe distance from the motor.

Never stick one inside the stator of a damp motor for instance (disclaimer: this blog is for information only, and should not be relied on legally, as its free. If you injure yourself, due to lack of proper formal training, then I accept no liability)

Periodically you can re-check the Insulation Resistance readings, until they have risen back up to acceptable levels, and the motor is dry.

Important note:  Sea water is corrosive, and the motor is likely to need washing / cleaning out, with fresh water etc, before you start the drying process.

The second method that can be used, is to gently heat the windings up using a lectrical welding set.

A  low current from the welding set is passed through the windings, which causes them to gently heat up, which helps dry them out.

I am not going to elaborate on the second point too much, as you really need ‘hands on’ training on how to do it, and I accept no liability / nor want you to injure yourself.

Your marine training provider can show you how to do this.

Once the windings have totally dried out, and the insulation resistance is back to the pre ‘flooded’ levels, then the motor can be reassembled and re-connected.

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Labelling kids with special needs is counter productive.

Is Labelling kids with special needs is counter productive.

As a former supply (substitute teacher, I had the privilege to work in over 50 schools.

This experience covered both primary and secondary schools, which gave me a fantastic insight into the attitudes of many children.

One think I noticed was that some children would use their special needs statement, as a reason why they could not attempt a new piece of work.

Once such example was a year five girl, who stated that she could not start a maths task, because she had been told she was dyslexic!

With encouragement, and clear explaining of the task, she was able to start and complete the task, however this initial reluctance to start was concerning.

It could well be that she needed further task explanation and support, but she was quick to define her abilities to attempt a task, by her ‘statement’.

Whilst I am not saying that we shouldn’t put support in place to maximise student attainment potential, there is the danger that students can start to identify themselves, by the educational ‘label’ they have been given.

Why are we trying to get fish to climb trees

Fish are brilliant swimmers (except dead fish), but generally lousy tree climbers.

We as human beings are all unique individuals, all with valuable skills and insights, to potentially contribute to improving society.

Whilst we are all one species, we do differ in many ways, compared to other species.

Do you know any greyhounds with dyslexia, or chimpanzees with ADHD.

As human beings we are all brilliant and talented, but in schools sometimes it seems like we are trying to get fish to climb trees.

I say that we are trying to get fish to climb trees, because surely ADHD, or any other educational label is just trying to understand and fix, the fact that children are different.

We are trying to get all children to fit in to a narrow definition of success, within the school environment.

Attempting to get all children to achieve in a narrow definition of success, suits schools & Ofsted, but not children.

We are surely failing our children’s mental health and self esteem, if we are forcing them to be something they are not.

Whilst we can argue about the relative influences of nature versus nurture on a child’s development, the fact is that we have natural abilities and talents.

A potential new approach to schools

We have the opportunity to creatively redesign schools for the future of society.

Primary school should be about discovering & nurturing a child’s passions and interests, not getting stressed taking SATS tests. We should also not be labelling kids at such an early age.

If a child shows an early interest in music, then tailor a personalised education plan around music.

I’m not saying forget maths and English, but these can be made relatable to the child’s core interest (s).

Childhood should be a joyous experience of personal discovery, not an attempt to fit in to a narrow range of learning criteria.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

My Personal Passions & Values

Passions & Values:

Helping people
Breaking down inequalities
Helping people believe they can constantly improve themselves.
Challenge conventional processes & ways of thinking

Values:

Open
Internationalist, with a belief in close friendship & cooperation between nations.
Believer in taking international best practice, and applying it to local communities. To constantly improve the lives of those who live in those local communities.
Adventurous spirit,..likes to try new & different things.
Curious,..likes to experiment & learn, even if I fail…its ok, as I learn.
Human rights….I don’t care where someone was born…I got lucky (being born in a safe & wealthy country), so think everyone should be treated equally, no matter where they were born.

Philosophy:

If I punch you in the face, you are likely to punch back! Conversely, If I let your car out of a side street, you are then more likely to do the same for someone else, further down the road (it works).

Preferred business working environment:

Flat organisational structure
Laid back and friendly
Creative ideas valued, and encouraged
Everyone in the business genuinely valued……the dustman that collects the bins from the Prime Ministers house, is just as important as the prime Minister…..they are both part of a team……remove one, and the system breaks down.

Marine Electrical Training Online

My passion is vocational education, and helping others to succeed.

I formerly worked in marine electrical training, as a marine electrical lecturer and trainer at South Shields Marine School, in the UK.

During that time I was privileged to help upskill trainee electro technical officers, and deck cadets, from companies around the world.

I am so proud to have worked with people from many countries, including Nigeria, India, Qatar, as well as the UK.

Examples of companies whose employees I have trained, include Carnival Cruises, Royal Fleet Auxiliary, and the UK Border Force.

I also trained electrical apprentices from organisations, such as the NHS, and industrial maintenance engineers.

MY SERVICES
I work in RF Systems & Electrical Training, offering a worldwide service. I am proud of my numerous happy clients who have improved their theory knowledge, practised vocational maintenance skills on real machinery, built their confidence, and met their career ambitions.

Car Maintenance Tutoring Course

Car maintenance knowledge is not just for mechanics.

Having a good understanding of how a car works, helps empower you, when visiting a repair garage.

The course objective, is to equip you with an overview of the main components that make up a vehicle.

Components include the parts which make up an engine, such as head gasket, cylinder head, and camshaft.

You will also learn about the ancillary components attached to the engine, such as the alternator, and sensors.

Both petrol & diesel engines are covered.

Additionally I can offer optional tutoring on electric vehicle technology.

In addition to vehicle engine components, vehicle suspension systems are also covered. Examples include steering components & Shock Absorbers.

The aim is to make car maintenance more understandable.

Morris Minor Electric Motor Conversion Kit

Morris Minor conversion to electric motor power, is a topic that I am contacted about via platforms such as LinkedIn.

It can be confusing when starting a Morris Minor conversion, to know what parts you need.

When starting a Morris Minor electric conversion, the first thing to decide is what sort of performance you want.

Performance is measured in terms of maximum speed, maximum mileage range on a single charge, and acceleration time.

Lets first consider maximum speed.

An electric motor is capable of spinning much faster than the original Morris Minor engine.

The original Morris Minor petrol engine ranged in size from 803cc, up to 1098cc, depending on year of production.

The gearboxes that the engines were attached to, were also uprated in the later version (known as the ribbed case gearboxes).

For arguments sake, lets assume the maximum original Morris Minor engine speed is 6000 RPM.

That means that the Crankshaft (spinning output shaft from engine) is rotating 6000 times in a minute.

The Crankshaft is attached to the cars gearbox (input side), via a clutch mechanism.

At the other end of the gearbox, is a rotating output shaft.

The engine and gearbox layout on a Morris Minor, is known as longitudinal, which means that the gearbox sits at the back of the engine.

By contrast most modern cars have the engine and gearbox mounted in a ‘transverse’ arrangement, where the gearbox is mounted on the side of the engine.

Transverse engine / gearbox arrangements are normally used in front wheel drive cars, whereas Longitudinal layouts are used in rear wheel drive vehicles. There are of course always a few vehicles that don’t follow this rule.

 

To be continued, when I get time, so come back regularly.

 

Hospital Cleaning Monitoring Using IOT

Hospital cleaning monitoring can help optimise patient safety.

Hospital cleaning monitoring can be split into two categories:

The two categories are ward cleanliness, and cleaning equipment location.

Daily Hospital Ward cleanliness is the responsibility of ward staff such as nurses and housekeepers.

In addition, wards are periodically closed for what is known as ‘deep cleaning’.

Deep cleaning involves taking beds and furniture apart, to clean any hairs and dirt, that may have been missed during regular cleaning.

Once the deep cleaning staff have completed this task, the Ward is sealed airtight, and a special machine pumps special vapour into the ward, to totally kill off any remaining germs.

Once the deep cleaning process has been completed, the hospital ward is ready to be handed back to the ward staff, to re-open.

Hospitals are busy places, and despite periodic deep cleaning, germs may accumulate, his is where IOT can help.

IOT, which is short for Internet Of Things, allows sensors to monitor a variety of environmental conditions.

This data is then periodically sent from the sensors to a device called a gateway.

The job of the gateway, is to put the data received from the sensors, into the Internet ‘cloud’, or local (in building) server.

By attaching appropriate sensors to areas such as the floors of wards, water supplies and beds, enables fast reactive maintenance to resolve high contamination levels.

By using sensors to ‘know’ when areas of a hospital need cleaning, enables the cleaning schedules to be scheduled based on need, and not fixed set periodic timescales.

Legionnaires Disease procedures are carried out in hospitals on a daily basis.

The disease can spread in water systems that are infrequently used, therefore taps have to be run every day.

The task of running hospital taps & showers, is usually carried out by healthcare assistants, or housekeepers.

Taps are run for a minimum of two minutes, and in many hospitals paper based recording systems are still used.

The completed paper based forms are kept, as legal proof that the task has been done. These forms are signed and dated daily.

By incorporating sensors into the water pipes, and feeding the data back to a central location, bacteria levels (Legionaires disease etc), can be monitored.

The second hospital cleaning monitoring category, concerns location of physical cleaning assets, such as mops, electric floor polishers, and even ‘wet floor’ signs.

In my experience of working in a hospital, equipment tends to move around, and is often hard, to track down its location.

This is due to staff on different shifts, needing equipment, and coming and removing it from where it normally is located.

By incorporating wireless sensors, physical assets can easily be located, which saves time.

Another bonus of incorporating location sensors into cleaning assets, is that electrical items can be found for PAT (Portable Appliance Testing).

Author: Craig Miles , founder of Yesway Ltd.

Power Steering Belt Change On Jaguar Diesel Car

Power steering belt change is required periodically on most cars.

The exceptions to this are cars with electric power steering, and those with no power steering.

The car that I did the power steering belt change on, is a 2006 Jaguar X-Type 2.2 Diesel.

The very first step was to purchase the correct belt.

Make sure you check that the product code matches suitability for your vehicle.

The first task was to remove the plastic engine cover, as shown in the next photo. The cover is held in place by round rubber supports, and the cover is removed by pulling upwards, from the front first.

Before trying to pull the engine cover off, you need to first remove the oil dipstick, as the top of it is wider than the dipstick cutout, in the engine cover.

Jaguar Engine Cover

After successfully removing the plastic engine cover, the next stage is to remove the battery.

Firstly remove the negative (-) battery terminal, followed by the positive (+).

The reason for firstly removing the negative terminal, is that if the other end of your spanner comes into contact with the cars bodywork, it won’t cause a spark.

You will need a 10mm spanner or socket, to remove the battery terminals.

IMPORTANT: Removing the battery will reset the cars radio, and therefore you will need to have the appropriate security code.

Once the two battery terminals have been removed, you then also need to undo the two nuts holding the battery support clamp.

I found that only the rear nut needed to be taken off completely, as the top plate of the clamp, will rotate out of the way.

Battery Box.

Once the battery has been removed, the battery box lifts out of the cars engine bay.

You will notice from the photo above, that there is a wire attached to the plastic battery box.

This wire, along with a pipe was fixed to the box, but not connected to anything.

You will need to unclip these from the battery box, before lifting clear of the engine bay.

Power Steering Pump

Next task is to unclip the electrical connector from the air intake, as shown in the photo below.

You also need to remove the air intake pipe, as also shown in the photo.

To remove the pipe, you squeeze together the two ‘lugs’ on the clip. This should then allow you to pull the two halves of the pipe apart. Its the front part that needs moving.

Air Intake Pipe.

Next remove the bolt at the front of the power steering cover shown below. You will also need to carefully pull out the release tab, on the other side of the cover (nearest back of engine bay).

Power Steering Belt Cover.

Then remove the bolt shown in the photo below.

Removing support bracket.

And this one!

Now you can start to remove the belt.

Firstly you will need a square socket to fit into the hole on the side of the tensioner pulley.

Once the socket is in place, rotate it in a clockwise direction, to slacken the tension on the belt.

Starting with the bottom of the belt, which goes round the power steering pump, use a long flat blade screwdriver, to gently prise the belt off the pulley.

I really wouldn’t advise using your fingers to pull the belt off. This is because if the tool used to move the tensioner slips, you could trap your fingers.

Once the belt is off the bottom pulley (power steering pump), you can remove it from the top pulley.

At this point you will realise that the belt will not come away from the engine, due to an obstruction.

You need to slacken the screw as shown below (holding the L shaped bracket), and the bracket can be moved out of the way. This then allows the belt to be removed.

Fitting the new belt, is a reverse process of the above instructions.

Firstly fit the belt to the bottom pulley, and then the top.

Then release the tensioner, and check that the belt is correctly in place.

 

 

Disclaimer: This article is for entertainment purpose only, and I am not at all liable for any consequences of you using it.

 

(C) 2020 Craig Miles

@acraigmiles

https://www.linkedin.com/in/craig-miles/

 

 

Supermarket Automation Improvement Using Robotics & IOT

Why Most Supermarket Automation Systems are Currently Rubbish!

Supermarket automation is something I had not thought about, until coronavirus lockdown.

This changed shortly after the start of lockdown, when I got a job at a local supermarket.

Having been employed there for nearly four months from 1st April, through to late July, allowed me to observe how it worked.

Input-Process-Output

Lets consider a supermarket in terms of a machine.

In automation systems, such as PLC‘s , you can break the system down in terms of an input stage, followed by the process stage, and then the output stage.

In a supermarket, the input stage is the delivery of physical products by delivery truck.

Once the goods, such as baked beans are delivered, then we move on to the ‘process’ stage.

The ‘process’ stage in a conventional supermarket, begins with the goods being taken off the delivery truck on wheeled metal trolleys.

The trolleys are bought into the back of the store, wrapped around with cellophane plastic.

The goods contained on each trolley, are not placed on each delivery trolley, in any logical order.

For example, a typical trolley could include beer, next to breakfast cereal, and toilet rolls.

This seemingly random loading of the delivery trolleys, has two problems:

The first problem, is that the delivery trolleys are large and heavy, therefore the products need to be unloaded into smaller trolleys, so that the products can be taken into the ‘shop floor’.

The supermarket team leaders manually make up smaller trolleys, from the larger delivery trolleys, for staff to stock the shelves with.

This ‘making up’ smaller trolleys of goods, from the larger delivery trolleys, is inefficient in terms of staff time, and ultimately therefore money (wages).

Secondly, the time delay involved between unloading from the delivery truck, and getting the products onto the shop shelves, has potential food safety issues.

Some of the products that arrive on the delivery trolleys, are refrigerated goods.

Whilst it should be stated, that the refrigerated goods are all on the same delivery trolley, there can be a delay in getting the goods into the stores refrigerated cabinets.

More on supermarket automation, to come soon……

 

 

 

 

Garden Design Lighting using Lorawan

Garden design lighting is often used to enhance the visual appeal of gardens, and can be improved further using LoraWAN.

LoraWAN is a wireless communications technology, used to send data between devices.

Advantages of LoraWAN for garden design is its long range, and low power consumption.

The advantages of LoraWAN long range are pretty obvious, and allow lighting control over large areas. This is a positive advantage for large garden areas, such as stately homes and parks.

One issue with loraWAN, is that it is not designed to use optional ‘repeaters’.

Repeaters are devices in wireless radio communications, which receive a weak radio signal, and re-transmit it, at a stronger signal level.

Repeaters solve the problem that occurs with radio signals, at frequencies above 30 MegaHertz (MHz), at which radio signals are ‘line of sight’.

Line of sight means that physical features, such as hills, and buildings made of certain construction materials, will block radio signals.

Therefore physical obstacles ‘could’ block or reduce (attenuate) the LoraWAN radio signal.

Fortunately by careful positioning of LoraWAN devices can be an effective workaround.

So hopefully now you understand that LoraWAN is a wireless technology, used to send data, over wide physical areas, and at low power consumption.

You may however be wondering how it can be used in garden design lighting.

Firstly lets consider how we power lighting in the garden.

There are two methods available, solar and fixed Steel Wire Armoured (SWA) cabling, buried in the ground.

Solar has become a popular option in recent years, due to its ease of installation.

Most solar lights, have a small solar panel incorporated into the light design.

Therefore installation costs are very low (or free), as they just need putting where you want them located.

The disadvantage of solar lighting, can be light output levels.

This is because of the fact that the more light you want, the more power is consumed.

Therefore if you have bright lighting, it will have higher power consumption requirements.

Solar systems have small batteries incorporated, which store the electricity generated on sunny days, by the solar panels.

A bright light that has higher power requirements, will drain a small battery quicker, than a light with lower power requirements.

You might decide to have a larger storage battery, to supply the brighter light.

Unfortunately you would also need a larger solar panel, to charge it.

Hopefully you now understand, that having a decent level of light output from a solar based system, can be an issue.

Of course a system could be designed, using a large separate solar panel, and storage batteries. Such a system would then supply the lights, via cabling.

Such as system may work sufficiently well, in countries with high levels of all year sunshine, but not in many countries.

For most situations where high output garden lighting is required, a wired system is needed.

In its simplest form, a garden lighting system, could consist of a single cable, supplying all the lights.

Traditionally this would mean that all the lights would either be on, or off at the same time.

That’s ok, if you want to be boring, but what if you want to individually control the garden lights separately.

The ‘old fashioned’ method would be to have separate cabling from each light, to a control box.

The disadvantage of this method, is the high cost of installing individual cables.

It is also inflexible, as it is inconvenient and expensive, to alter the lighting at a later date.

A better way is to run a single cable, but control each lighting fixture, using wireless radio signals.

A number of technologies will achieve this, but LoraWAN is ideal, due to its long range.