What is is Auxiliary Contacts and it's working in Contactor?

In Electrical Power wiring we use different types of relays and contactor / motor starters and these have some contacts which we know with names of main contacts and coil contacts but this is not end we have also other contacts which we known with name of auxiliary contact. These contacts are available in every contactor but these auxiliary contacts in different types just lick Normally close and normally open which can set or fit on the contact or / motor stater and person can use it for different types of works. But the reason of this post to learn that what is auxiliary contacts and what is the work of auxiliary contacts on a motor starter.
So lets start it step by step.

What is Auxiliary Contact and A Contacts on Contactor?

Auxiliary means helper or we can said these are helper contacts in magnetic contact or relay which help us to done our work easily. And one thing more with out these contacts we can not control any thing by using magnetic cont actor.
So these are also important contacts lick main contacts. On thing more these contacts are available in in ever motor starter but in Small and low ampere (load) contactor we have these contacts only on one side but in big and high loaded motor starter we have these contacts on both sides. In these contacts one is normally close (NC) and other one is normally open contacts (NO). Which we use for different purpose.

What is the work or Auxiliary contacts on a motor starter ?

These points are very important in motor starter and without these contacts a contactor is incomplete. As i written in my above words that in these contacts in one is normally close and 2nd is normally open circuit.
These contacts is directly proposal to the setting coil and when magnetic contactor coil energize and set, the normally close contacts become a normally open contacts and normally open contacts change to the normally close contacts.  Form these change we can control many things which can see it in my last published post about controlling three phase motor using cont actor. So get look on these post.

Also reed below:

How to wire a three phase induction motor with contact?
How to wire a phase failure relay for 3 phase appliances?
What is MC?
MC / motor stater instillation for single phase motor

You can also get an idea about the working principle of auxiliary contact s from the above post links however lets get an review the working of these contacts.

For example

• With out these contacts we can't do proper connection of a 3 phase motor or a three phase appliances.
• By using these A-C (A cont...) we can do the star delta starter connection for three phase 6 wire motor.
• By using these A-C we can control a two contactor with one another, i.e if we have 2 contactor which we instill in our main board and both are instill for different machines. But if we want that if a machine is start then other one does not start then we can easily use these contacts for that type of work.

The above example is not too close to understand completely, however you can get an idea and if you try and think about that, i hope you will do it. However every thing when we start learning is not complete learned in a short time and it's required some time.
Further in our post we will use these contacts in circuit and IN SHA ALLAH you will learn if you gave it short time.


Now lets get a view about these Auxiliary contact s, in the below image i shown these contacts in animation - type look + images from which you can learn it easily.

Now one thing more in ever A contacts we have tow types of contacts in which NC and NO. But in contactor we have move able contacts when circuit or A-C in normal state the NC will NC and NO will be NO but when conactor energize  or these contacts are set by using any force the NC contacts will change to NO (normally open) and NO will be change to NC (normally close). You can get an idea from the below image plus diagram.

I hope after the above image + diagram of auxiliary contact 's , know you understood completely, however as i told in my above words that further we will publish the diagram in which we use these contacts and you will completely understood how to use these A-C.

Phase Controller Wiring / Phase Failure Relay Diagram

When we talk about the 3 phase power wiring or designing or installation a three phase electrical panel board, the fist and important thing is designing and protection. phase controller or phase failure (phase sequence) device is protection device which is better for three phase power board or for a 3 phase electrical machine. A Phase failure is a device which is not too big and not having price but i think without this a three phase electrical main panel or distribution board is incomplete.
In this post we will lighting about Phase failure and it's advantages, in short word we will called phase failure in this post with name of  PF.
Not only we talk about it's working but also we will talk about it's wiring connection and uses in 3 phase electrical panel or distribution board.

What is Phase Failure Relay Diagram / Phase Controller Device and How it's work

In simple word a PF is a protective device which we use in 3 phase main boards, sippicly we use it in those panel board in which supply goes from a magnetic contactor. When one of phase cut or not coming to the main board the phase controller automatically switch off the all supply, my means that PF device switch off the cont actor coil current and contactor switch off or cut off the power supply.
In short a magnetic contactor is required for PF or controller. However i want to gave another example from which you will understand the importance of phase failure device controller.

E.g Example :

If you wire a 3 phase motor with a contactor / motor starter and you start your motor by pressing the green push button. Now your motor is start and working but in case one of your phase is cut or not coming to main board. or you main circuit breaker one point is not working. So in this case your main board and motor missing one phase, in this time the PF device will active and switch off your magnetic cont actor or we can say that it's will cut the magnetic contact-or coil current.
In this phase controller internally install a relay and circuit which measure the phases and switch off the relay when one phase is missing  to the phase failure circuit.

As you know that we all use overload relay for protection with three phase machines but in case of one phase missing the relay working and activation required some time to protect you machine. However if we install or wire phase controller in our main panel board then we can safe our all electrical 3 phase machine in same time when phase is missing or we can said this is double protection.

How To Connect Or Install Phase Controller /  Phase Failure Relay  Diagram

A PF device is a type of relay which working principles is regarding the phases. This device have 3 point which for L1 L2 L3 and when we connect 3 phase power supply to these contacts they relay circuit active and start testing phases. In this device a relay is install and they have three points in which one is common and other are Normally open (NO) and normally close (NC). When our main circuit breaker is off, the PF device relay is NC between 1 and 2 Point, and when we switch on our main circuit breaker, the 3 phase supply start to the phase failure device and the device relay energize and make a NC connection between 2 and 3 contacts.
In Case if our one phase is missing in circuit, the device will de energize the relay and it's make again NO contacts between 2 and 3 points.

I hope you understood the working of phase failure relay now lets talk about the below diagram, in the below diagram i connect a phase failure with circuit breaker and contactor / motor starter and overload relay.
In the below diagram i completely wire a 3 phase motor because if i did not shown the complete method and only shown the phase controller then you will be not understand completely.

Note due to wrong connection done, the above diagram is update

In the above diagram i shown the complete method of wiring or connection of phase failure relay diagram with circuit breaker, cont actor, overload relay, push button switches and electric motor, however lets talk about this step by step.

• First of all do connection between mcb circuit breaker and contactor / motor starter.
• Then Do connection between the 3 wire between contact or and overload relay.
• Then get three phase connection for PF phase control device and connect it as shown in above diagram.
• Then get a connection L1 point in PF device and connect to the common point for relay in PF which is 2.
• After that do connection between PF point 3 and overload relay NC point 96.
• After get connection from the overload relay point 95 and connect it to the contactor normally open auxiliary point and red push button which is normally close.
• Then get wire connection from other connection point of Red switch which off push button and connect to the switch on push button which green push button which have normally open contacts.
• Now do connection between green switch and cont actor other side normally open auxiliary contacts point and then connect a wire here and provide it to the cont actor coil.
• Now get connection from L1 which shown with Red color and connect to coil other side as shown in above diagram.
• An Last provide the incoming supply to mcb (miniature circuit breaker) 3 pole CB and after that switch off the circuit breaker and do connection between three phase electric motor and overload main contacts.

Also read Below
How to wire 3 phase motor?
How to wire 3 pole mcb?

I hope now you completely understood the wiring of phase failure relay or connection phase controller, INSH ALLAH i will write more helpful post about electrical technology.

Note that some phase failure relay or phase controller have also a Neutral point and you must provide the neutral to device. This will highlight or named with N or mp.

3 Phase kWh Meter Wiring Complete Guide

Last time i write about the single phase EM wiring and in this post i am writing about the 3 phase kwh meter wiring and it's connection diagram.As you know that we use two types of electrical appliances regarding it's rated voltage, in which some are for single phase and some are required 3 phase, just like this we use two types of kWh meter in which one for single phase and 2nd kWh meter 3 phase.
In single phase supply mostly we use 110 or 220 and in three phase our voltage 380 to 440v.
In this post i am writing about three phase kwh meter wiring connection which is too simple wiring connection and also it's installation is too simple but only for professionals because in in single phase power source we have one neutral and one phase and in three phase 4 wire system we have 3 phase which manse the dangerous is more then two time from single phase power source.

3 Phase KWh Meter Wiring Complete Guide

As you know that we use different colors of wires for different substance and places. For single phase we use two colors which red and black. Black for neutral and the Red for phase or Line.
Just lick this we use red, Yellow, blue for three phase and red yellow blue and black for 3 phase 4 wire system.

In single phase kwh meter we have 4 terminal in which the first one for incoming phase wire which is come from the main distribution utility pole and 2nd one for neutral which is also come from the main distribution pole, the 3rd thermal for out going N and the last one is for out connection of phase to load.

As in single phase kwh meter wiring we have 2 connection points for incoming and 2 for connection points for out going just lick this in 3 phase kwh meter wiring we have 4 connection points for incoming and 4 for out going connection.

For single phase we use the 2 core wire, for 3 phase we use 3 core wire and for three phase 4 wire system we use the 4 core electric cable.

As we know that the 3 phase kwh energy meter is design for three phase 4 wire system, so we use the 4 core electric cable for this, however in the diagram i will show single core cables from which you can learn easily.

Three / 3 phase kwh meter wiring diagram

In the above diagram i shown how to wire or install the three phase energy meter. In the above diagram i shown cable in single single core for your better understanding, in real life we reconnected 4 core electric cable for the 3 phase energy meter installing.
In the above diagram i shown utility pole from which i get connection to the meter and then get connection for load from the EM.
The energy meter wiring connection is same as i shown in the diagram.

In diagram i shown read yellow and blue for lines and black for neutral, and shown all cables in single core but in real life use the 4 core or 4 wire cable for 3 phase kwh meter. If  the 4 core electric cable is not available you can also use the single core cables or double core cables but the best option to use the 4 core cable.

I hope know you understand the complete process of kwh meter 3 phase wiring and installation, one thing more that the method of wiring of analog and digital three phase energy meter is same.