Archives October 2015

Applying the Internet of Things (IOT) to Induction Motor Monitoring

Induction motors are found in all sorts of industries and applications, both on land and offshore.

Smaller Induction Motors (roughly drawing up to 10 Amps Full Load Current) most commonly use Direct Online Starting (D.O.L) methods.

Larger motors typically use starting methods such as Star-Delta starting, which keeps the starting current (surge / inrush) down.

The Internet of Things offers 24/7 monitoring of systems, which can intelligently react based on the input data provided by the networked sensors.

The main parameters of induction motors that could be measured are:-

Voltage (individual phase)

Current being drawn by motor.

Over current in individual phases, such as imbalances due to single phasing faults.

Phase Winding temperature based on measurement using thermistors.

Vibration Monitoring, indicating bearing failure.

Motor speed (inc comparison of actual to Synchronous field speed calculated speed).

What do we mean by the above parameters:-

Firstly lets consider the term, ‘Voltage (Individual Phase)’.

Voltage (individual phase)

The term ‘individual phase’ is applicable in three-phase supply systems.

Three-phase supplies are commonly used in industrial factories and workshops.

It is rare to have a three-phase supply in a domestic home.

To understand a three-phase supply, lets first consider a single-phase voltage supply.

In single-phase voltage systems (as found in most homes), an ac sine waveform ‘cycles’ above and below the centre zero volts level, at a frequency of 50 times a second.

This is known as 50 Hertz, or Hz, and is the supply frequency used in most, but not all, countries around the world.

ac sine wave.

The picture above, shows a representation of an AC (Alternating Current) Sine Wave. The line through the middle would be zero volts, and as you can see the voltage rises and falls over time (time periods, starting at the left of the picture, and moving right).

For an AC voltage supply frequency of 50 Hz, 50 complete sine waves would be completed, per second.

Now that (hopefully) you understand what a sine wave is, you need to know that in a single-phase system, you have one sine wave, that goes up and down over time (as in above picture).

A three-phase voltage supply, has three sine waves at the same time. NOT ONE, BUT THREE!

Each of the three sine waves, is spaced 120 degrees apart, which means in plain English, that they rise and fall, at different times to each other.

For the purposes of Induction Motor Monitoring, you might want to monitor the phase wire, to check whether the voltage is on or off.

If the Induction Motor was a single-phase type, then obviously if the voltage supply was off, the motor would stop.

However, the single-phase motor may be tucked away from view, in a corner of the factory. Therefore being able to monitor the single individual phase supply, is still useful for an IOT induction motor monitoring system.

Being able to monitor all three voltage supply wires, to a three-phase induction motor, is even more useful.

If one of the three voltage supply wires, to the induction motor stopped supplying voltage, the motor would continue to run.

The motor would not run well on only two supply wires, but may go unnoticed, if in an out of the way location.

This is why using an IOT monitoring system, to detect the voltage of each of the three voltage supply wires, is useful.

Current being drawn by motor

Each Induction Motor will have a manufacturers specification for how much current is drawn, both at startup, and when fully running.

For more information on induction motor monitoring , get in touch.

(c) Craig Miles 2015-2020. All rights reserved. www.craigmiles.co.uk @acraigmiles

Internet of Things | Two Way Radio Wireless Communications – Yesway Communications

Challenge of Installing IOT Sensor Equipment in Explosion-Proof Areas, by Craig Miles

IoT, or the Internet of Things is already changing the way that businesses function, and this is set to explode in the forthcoming years.

IoT is all about improving business efficiency by collecting information (via sensors) about the physical world (Inputs such as temperature, pressure, location, etc), and then using this data to trigger an automated action, based on the data.

Installing the sensors that provide the ‘inputs’ to your IoT system is usually fairly straightforward in most environments, however potentially explosive environments require special considerations.

When installing any electrical or electronic device in a potentially explosive environment, the device must be rated as ‘EX’ , also known as ‘intrinsically safe’.

Intrinsically safe electrical equipment is available as components such as electric fans, cable glands, and hand-held two-way radios.

This is a business opportunity for IoT device manufacturers to create ‘EX’ rated sensors.

The main thing to consider at all times when designing your install is will my equipment cause a spark, potentially causing an explosion.

First, consider your sensor itself. An example is a sensor located in a ship’s battery room to monitor and report on voltage and a specific gravity of the lead-acid batteries, used for emergency backup.

The sensor you use to collect the information MUST be EX rated / intrinsically safe, to be compliant.

The next consideration is how you are going to get the data from the sensor ‘out’ of the potentially explosive area and to the location where the data is processed.

Wireless technologies such as Zigbee, WIFI, and LORA could be used, but by definition produce RF radiation which could potentially cause an explosion. Therefore it is crucial that only equipment that is EX rated is used.

In the case of environments hostile to RF (Radio Frequency) Radio Waves, such as ships, oil rigs, and other buildings with high metal content, an alternative would be a fixed wired solution.

When using wired methods to transmit sensor data, the cable gland must be designed so that the explosive area remains gas-tight, to prevent explosive gases from interacting with electrical components outside the intrinsically safe area.

Glands for this purpose exist and can be found online.

To conclude, the key to installing the Internet of Things (IOT) in a potentially explosive environment is to ensure that every piece of IoT equipment that is installed is EX rated to prevent explosion risks.

You also need to think about and ensure that any wiring that leaves the intrinsically safe/explosive area goes through properly rated EX glands, to ensure safety.

For more information on the Challenge of Installing IOT Sensor Equipment in Explosion-Proof Areas, why not contact us.

The author is Craig Miles (me) and I can be contacted via www.craigmiles.co.uk

All content is copyright, and copying and all rights are reserved (c) Craig Miles 2015

Internet of Things | Two Way Radio Wireless Communications – Yesway Communications