Earthing Systems On Ships Insulated Neutral Versus Land

Insulated Neutral on Ships


The difference between land based power delivery and the earthing system on ships (most, but not all).

  • Land based = Connected neutral & earth
  • Earthing systems on ships = Insulated neutral, not connected to ships hull

Land based connections

  • Main priority is maximum protection of people and livestock.
  • Neutral & earth connected together at local substation (step down transformer), and also where the cable enters the building.
Earthing systems on ships

Most ships have an ‘insulated neutral’  electrical system.

As the name suggests, the neutral wire is insulated from the ships hull, which is the closest thing to a land based earth aboard ship, at sea.

Insulated Neutral Practical Differences

On land, an earth fault would cause the Residual Current Device, or RCD,  to trip.

The system is designed for maximum protection of people & livestock.

At sea the main priority is safety of the ship.

If critical systems such as steering gear were the trip, due to a single fault, then it could potentially be catastrophic.

Therefore on ships a single earth leakage fault between the power and the ships hull, can happen without tripping the circuit.

What happens instead is that an alarm will be triggered on the ships earth fault monitor panel.

It is important that a single earth fault in an insulated neutral system is repaired as soon as possible.

This is because if a second fault should occur, then the circuit will trip, which could out the ship at risk.



Wireless Outdoor Intercom Linked Two-Way Radio Designing

This blog article is about the design process of designing an outdoor wireless Intercom.

Background To Project

An existing industrial manufacturing client emailed me to ask if I could ‘programme up’ a couple walkie talkies.

The customer needed to start locking their store room when unattended, due to workers helping themselves to supplies.

They wanted to mount a couple walkie-talkie radios on the wall, so that workers could call for the store to be unlocked.

The client wanted one radio to be mounted directly outside the storeroom, and the second outside the building.

They thought that perhaps the radios could be mounted in some sort of external case, to protect them.

This is especially important for the radio mounted outside the building, due to rain and snow.

The potential problem with mounting expensive handheld two-way radios outside, is also theft.

The clients site is on a secluded industrial estate, and the entrance to the car park, and hence the exterior of the building is open.

After clarifying with the client as to exactly them wanted, I sent them the rough idea for a radio linked Intercom.

The photo above shows the rough initial idea for a wireless outdoor intercom.

Luckily it was exactly what the customer was looking for.

So now I knew what they client wanted, all I needed to do now is figure out how to make it work.

RF Electronics Options

The design brief from the client, requires the intercom to be able to call the portable digital two-way radios that the factory managers have.

The purpose is so that they can come and unlock the storeroom, or unlock the outside door (both of which are now locked).

After a personal brainstorming session, I came up with the following options.

  • Bluetooth link, with audio capabilities.
  • DECT communication technology, like cordless phone.
  • Licenced PMR Digital Radio.
  • Unlicenced PMR446 Radio (analogue or digital)
  • Audio over Wifi

Once I had come up with the initial list of possible ways to link the intercom with the existing two-way radios, it was time to evaluate.

Firstly I considered Bluetooth.

Bluetooth was introduced in 1994, and is currently up to version 5.

In addition to what is now known as Bluetooth ‘Classic’, there is now also ‘Low Energy’, and ‘Mesh’.

As the names suggest, ‘Classic’ is an updated version of the original Bluetooth.

‘Low Energy’ is designed to use less current from its power supply.

This makes it suitable for the Internet Of Things, as enabled sensors can last for years on same battery.

Product like Smart Watches use Bluetooth Low Energy, or BLE as it is commonly known.

Bluetooth Mesh allows data to ‘flow’ through multiple ‘nodes’ en route to their destination.

This enables data to travel longer distances than would otherwise be possible using ordinary Bluetooth.

Mesh technology is great for controlling projects like Smart Lighting, but is not needed for our simple intercom design requirements.

As you hopefully have now appreciated, there are different types of Bluetooth for different purposes.

Bluetooth was originally designed as a technology to wirelessly replace RS232 type Serial communications cables.

It has also developed  into a technology capable of  transmitting audio.

Bluetooth modules capable of audio, have a Digital Signal Processor (DSP) included in their design.

Positives of using Bluetooth for the Intercom

The intercom has the following design requirements:

  • To allow instant wireless voice communication at the push of a call button.
  • Be capable of being powered by battery, with long battery life.

Bluetooth audio could provide the communication link between the intercom and the two-way radio.

It uses fairly low power consumption.

Could also be made to work with app on mobile phone, as all smartphones now have Bluetooth built in.


Relatively short range, which might be an issue, if the receiving Bluetooth module of the two-way radio, is too distant.

Time delay to establish the connection, unless left connected (which has power consumption implications).

At the time of writing (27th November 2019) , I am still researching Bluetooth technology in more detail, so I might still use it for the design.

DECT RF Technology

The next RF (radio frequency) technology that I considered for the intercom design, was DECT.

DECT is short for Digital Enhanced Cordless Telecommunications.

Sometimes you may also see it called Digital European Cordless Telecommunications, as the technology originated in Europe.

DECT has been adopted worldwide, and is most commonly used in cordless phones.

However I considered using DECT to provide the wireless communications link between the intercom and the two-way radios.


DECT provides clear two-way audio communication.

DECT operates at 1900 Mhz  (1.9Ghz) which has the advantage over Bluetooth & Wifi, which operate at 2.4Ghz (2400 Mhz).

1900 Mhz is an advantage because it is a less crowded frequency, and therefore less subject to potential interference from other users.


There is less choice in DECT modules available, compared with technologies such as Bluetooth.

The modules for DECT enablement of the wireless outdoor intercom also seem to be more expensive than Bluetooth.

Licenced PMR Digital Radio

PMR stands for Private Mobile Radio.

…..more information on the design project coming soon. Come back regularly.















Bluetooth Integration Services Smart Factories

Bluetooth Integration into existing factory machinery is possible.

By connecting a factories existing machines wirelessly to networks, smart factories can be created.

Integrating Bluetooth is an option for wirelessly Connecting machines to the Cloud.

Smart factories need to be able to closely monitor parameters, such as vibration and current of induction motors.

This allows the creation of Predictive Maintenance systems.

Using a wireless link to transfer data, rather than cables, saves installation time and cost.

Bluetooth is not the only wireless technology that can be used for smart factory integration.

The choice of the most suitable wireless link technology depends on a number of factors.

For example if long range, low data rate communication was required, then technologies such as LoraWAN might be better.

It is a myth however that Bluetooth is only suitable for short range communication.

Distances of up to a Kilometre are realistically possible.

Another option is to use the mesh version of the technology.

Mesh networks can send the signal over a wide area, by ‘passing through’ the separate nodes within range.

This can create a long distance network of connected nodes.

Internet Of Things Consultant services

Internet of Things consultant services for business.

The Internet of Things or IOT for short is the connection of machines, sensors and objects to the Internet cloud.

I can help your business with the Internet of Things consultant services by researching, designing and implementing solutions, tailored to your business.

LoRaWAN architecture and uses in Sensing

How to Build a Lorawan Gateway

Zigbee Technical Characteristics

What your Microwave Oven has in common with your WIFI

Connecting existing industrial machinery to local servers, or the cloud is something I can help with.

An example of a common piece of machinery in a factory, is the three-phase induction motor.

Induction motors can be connected to monitoring networks, to create Smart Factories.

Having early warning of potential problems with the induction motor can save a costly breakdown later.

This is known as Predictive Maintenance.

Parameters that can be monitored, include motor vibration.

Without smart sensors monitoring the induction motor, the vibration could go unnoticed.

Likely causes of vibration in an induction motor is worn or damaged bearings.

The bearings in an induction motor allow the motor shaft to rotate.

Worn bearings in a non smart factory would only become apparent, when immediate attention is required.

Replacement of worn bearings necessitates machine ‘down time’, which is costly.

The Internet of Things can help monitor induction motor condition, and therefore reduce expensive downtime.

Wireless versus wired connection.

For short localised connection, wired connections are easy to set up, and cheap.

However for longer distances between sensor and network, wireless radio links make sense.

The wireless technology that is most suitable, will depend on the industrial scenario.

Possible wireless technologies suitable for the Industrial Internet of Things (IIOT) include Bluetooth, WiFi & LoraWAN.

Factors which determine the most suitable wireless link technology include amount, speed and type of data to be transmitted.

For example if the requirement is to transmit live CCTV, then low data rate wireless technologies such as LoraWAN, wouldn’t be suitable.




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    

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.


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.




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 ~/ic880a-gateway
  cd ~/ic880a-gateway
  sudo ./ 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


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.


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

International Marketing lessons that McDonalds should have known before ‘Sundae Bloody Sunday’ Promotion

International Marketing

When I studied international marketing during my undergraduate degree in the mid 1990s, I learnt something important.

It is important to ensure that your brand name and advertising do not cause offence in some markets.

The case study we learnt was that of Toyota cars, who had produced a sports car called the Toyota MR2.

The original model MR2 was launched in 1984, but the name soon caused an unexpected issue.

You see ‘MR2’ when said out loud, sounds like something rude in French (basically Shit!).

Clearly no business wants their product to have this image, so the car was renamed for the French speaking market.

Now what has this got to do with yesterdays news about McDonalds in Portugal.

For those of you that didn’t read or see the news, McDonald’s has apologised  for accidentally causing offence with its ‘Sundae Bloody Sundae’ promotion.

For younger readers, and those without an Irish connection, the promotion sounded like ‘Sunday Bloody Sunday’.

‘Sunday Bloody Sunday’ happened in northern Ireland in 1972, and resulted in 14 deaths, by gunshots, during ‘the troubles’.

Due to the context of the deaths, it is still understandably a very sensitive matter for many people.

The point I am trying to get across in this article in international marketing  is that it is important to think internationally.

Thinking on an international marketing level was important for large business in the 1990s.

It is also now important for SME (Small & Medium Enterprises), due to the growth of the Internet.

Lessons to be learned

Personally I am surprised that a company like McDonald’s slipped up like this.

Normally they are experts in positive marketing of their products, and in creating a fun brand image.

Going forward I am sure they will double down on ensuring that promotions do not cause offence in other countries.

Conclusions and advice

Someone seems not to have checked that the advertising campaign would not cause offence outside of the local Portuguese target market.

Businesses should always check that they will not offend other countries that they currently operate in, or intend to in the future.

It is even more important now than it was in the 1990s, due to the Internet.



Main features of LPWAN Technologies

  • Low power RF technology
  • Low current consumption, therefore long battery life
  • Wide area coverage, compared with other technologies like Bluetooth Wifi.
  • Lower cost than mobile networks, such as 5G
  • Enable wireless connectivity of remote ‘field’ sensors to internet gateway devices.
  • A key component in the internet of things.
  • Suitable for devices and applications that require low speed data rates.
  • Not suitable for devices & applications requiring high speed levels of data transfer, such as cctv links. Wifi is a much more suitable technology for cctv links.


LPWAN is short for Low Power Wide Area Network.

The term was first introduced in 2013 for a technology designed for M2M communications, which is short for ‘Machine-to-Machine’ communications.

What is LPWAN

As a technology it provides a niche gap solution between mobile cellular (3G, LTE), and short range  technologies, such as Bluetooth, Wifi & Zigbee.

LPWAN is designed for machine communication rather than between humans.

Human communications consist of voice, video & data, and have different technical requirements to M2M.

Human electronic communications require high data rates and low latency (signal delay), while the user is moving around.

M2M requirements by contrast require low data transfer rates, infrequent transmission, and a low mobility requirement.

LPWAN technology is used by businesses to create their own secure data communications network.

Current LPWAN Technologies

It is available operating both on licenced radio frequency spectrum, and unlicenced radio spectrum.

Licenced Radio Spectrum IOT Technologies

  • NB-IOT
  • LTE-M
  • Thingstream

Unlicenced Radio Spectrum IOT Technologies

  • Sigfox
  • LoraWAN
  • RPMA
  • Weightless
  • nWave
  • SAT4M2M
  • hiber
  • Telensa
  • NB-Fi
  • helium







Single Phase Transformers How They Work

Single Phase Transformers

Single Phase Transformers are most commonly ‘step-down’ types.

This means that the voltage that comes out is less than the voltage going into the transformer.

The ‘transformer ratio’ of the winding’s on the input side ‘primary’ & output side ‘secondary’, determines the output voltage.

Example: 100 volts AC going in with a 10:1 (Primary / Secondary) winding ratio, would give 10 volts output.

  • Information about Single phase Transformers

    They may well be used in industrial environments, such as factories.

The transformers will be found in a variety of equipment around the factory.

For example inside larger Direct-On-Line (D.O.L) & Star-Delta Induction Motor Starters.

In such an application, the transformer is used to energise the coil inside the Contactor.

Another place you will find one is in a LoraWAN Gateway.

The LoraWAN Gateway which I built for Yesway Ltd, has one to reduce the 240VAC mains voltage, down to 6 VDC.

To get DC rather than AC, a recifier circuit is added to the output of the Secondary Winding.



Smart Factories

Condition Monitoring

Smart factories improve automation and efficiency compared to traditional factories.

Efficiency is increased both through process decisions being made without human intervention.

Efficiency is also increased by using sensor data to monitor the condition of machinery, such as three-phase induction motors.

Monitoring of induction motors, can include vibration sensors, which monitor the condition of the rotor bearings. A worn  bearing will cause increased running friction, which can be monitored by attaching external vibration sensors to the motor casing.

Other conditions that can be monitored on a factory induction motor, are rotor speed, Stator winding temperature, single phasing faults,  current drawn and voltage levels.

Other uses of smart factory monitoring systems, are the monitoring of the production process.


Smart Factory  Buildings

The factory building that houses the operational machinery, also forms part of  smart factories.

Automated temperature control has been around for years, and is also used in almost every home too. Its called an automatic thermostat!

Smart buildings can adapt the heating control automatically, by sensing where heat is needed in the factory building.

For example sensors, can detect if people are working in a particular section of the factory.

The sensor data is used to only heat the parts of the factory that require it.

The use of sensors can also be used to switch lighting on or off, depending on actual real-life demand for light, within sections of the factory.

Smart control of lighting and heating systems within the factory environment, reduces the variable costs of the the business operation.








What your Microwave Oven has in common with your WIFI

Radio Waves

What does your microwave oven have in common with your WIFI connection?

The short answer is radio waves.

A microwave oven operates by bombarding the food with high frequency radio waves.

A device called a Magnetron bombards focused electromagnetic waves at the food inside the microwave Oven.

This works by heating the molecules inside the food, which are tiny in size. The food molecules are vibrated by the radio signals produced by the magnetron, which causes them to heat up.

It is actually electromagnetic radiation that is cooking your food.

This radiation is dangerous, which is why there is a grid with tiny holes in the microwave door.

The higher the radio frequency in the electromagnetic spectrum  the shorter is the ‘wavelength’.

Microwave ovens operate at a radio frequency of 2.45 GigaHertz (Ghz).

WIFI also operates around 2.45 Ghz, hence the connection between the two, in this articles title.

As previously stated, microwave ovens have a grid incorporated into the door, which contains small holes.

These holes prevent the electromagnetic radiation produced by the Magenetron, from escaping out of the microwave cooking area.

The metal grid with holes in, is important because being cooked is hazardous to human health!

So is my WIFI also dangerous?

Whilst research has been carried out, and some people claim it is, you will not be cooked!

The reason for this is ‘RF Power’ level.

When RF (Radio Frequency) engineers work near very high power radio transmitters they use RF radiation monitoring devices, and appropriate protective PPE.

Whereas you will not get RF Burns’ using a handheld walkie talkie, or mobile (cell) phone.

Its down to RF Power levels being emitted from the antenna system.

Whilst RF frequency also is a factor, lets ignore that for the purposes of this blog article.

WIFI signals are low power radio signals, at a low RF Power. Hence you don’t get cooked, standing next the the wireless router.

Hopefully now you understand the answer to what does your microwave oven have in common with your WIFI connection?

If not, ask me a question, so that I can clarify and expand your knowledge.

(c) 2019 Craig Miles

Why not hire me!