In the industrial system, we use mostly three phases of electric power for electric induction motors. A single-phase induction motor can not do work as a 3 phase can be done. For 3 phase motor, we use some electrical devices for starting, off, and resetting, the magnetic contactor is one of them that’s why today we disuse contactor wiring with a complete explanation. In 3 power systems, we use some devices between the induction motor and supply which are a CB Circuit breaker, MC magnetic contactor or motor starter, O/L overload relay, and NC, NO push button switches for on/off and reset.
How To Do Contactor Wiring For 3 Phase Induction Motor With 3 Pole Circuit Breaker, Overload Relay, NO, NC Push Button Switches
In this tutorial post, I will tell you about motor contactor wiring and its diagram. But before we will disuse devices and working of these.
3 Pole Circuit Breaker CB
For the 3P power supply, we use a 3-pole circuit breaker for the switching supply. Always use a CB before circuit wiring, from this you can make your circuit safe and we will be able to switch it off/at any time. You can also use 4 pole breakers, which is very best because you can control also the neutral wire.
MC Magnetic contactor
For 3-phase induction motor start/stop we use always MC contact or. It is a type of electric relay which can switch the 3 electric connections easily. I also published posts about motor starter working you can see on the below links.
Click here for more information.
O/L Overload Relay
An overload relay is a protective device that makes safe our electric motor from burning during high current flowing to the induction motor. There are two popular types of O/L relays thermal overload relays and Electronic overload relay. In this wiring diagram contactor, I have shown the thermal overload relay however soon I will make a diagram about the electronic relay.
NC Normal Close Push Button Switch
For motor contactor wiring we use push button switches for switching on/off the motor. NC means normal close which means that this push button is normally in a close circuit and when we push, it makes an open electric circuit. I show NC with a red colour button and NO with Green colour.
For details Click here.
NO Normal Open Pushbutton Switch
The Normal open S is normally in an open electric circuit and if a person pushes this NO it makes an NC circuit. For further information visit the below link.
For more info click here.
MC Motor Starter Wiring Diagram With CB, MC, O/L, NO, NC
The symbol diagram is best but everyone can’t understand it easily that is why I always focus on image+diagram which is easy and simple to understand and good for learning. But you know that this diagram design takes bag time from the time of the symbol diagram. But I love my readers, as I am a student and struggling- for learning. I want to share all things which I learned.
Magnetic contactor relay wiring and circuit breaker, push-button wiring method is simple. And i think that there is no importance to explain more after making a diagram, however, let’s get a short tips journey.
For 3 phase motor controlling diagram and procedure, follow the below tips.
- First of all wire the CB Circuit Breaker but do not switch it On.
- Then Wire push button wiring O/L relay and MC coil, which we can call “small wiring” or “control wiring.
- Then wire the overload relay with MC.
- Then Do the connection between CB and MC.
- Then do a motor supply connection with the Overload relay.
- Then connect the earth-led wire to the motor body.
You can follow the same method as I have shown in the below contactor wiring diagram for wiring 3 phase motor with a circuit breaker, 3-pole motor starter, and overload relay.
In the above contactor wiring diagram, I have shown a 3-phase 440 volts 4-wire system. I take one phase and neutral wire for the MC coil which is 220V, but always wire your contactor coil regarding coil voltage / current requirements. If the coil required 110V to 120V then provide 110 volts supply and if it wants 380 volts to 440V to energize then connect the same required supply. The coil voltage cheat- is near the coil supply terminal/connection so check it first before starting.
In the overload relay, we have two options NC and NO. When the overcurrent flow from NC points, it makes an open circuit. Which are shown in the above image with 95-NC-96.
If you want to learn from the symbol contactor wiring diagram then click here.
The above is an example diagram of contactor wiring with an overload relay, and I hope that this diagram helps the newbie very much. But this is only starting and IN SHA ALLAH we will make more best contactor wiring and more tutorials for you.
Stay tuned…. and keep visiting……