In AC machine we use two types of machine in which is single phase and other one is 3 phase. These machine have there own wiring and controlling methods. 3 phase motor wiring connection and controlling is one of them. In this post i am gonna to share with you a complete guide of controlling three phase motor with magnetic contactor , thermal overload relay , MCCB (molded case circuit breaker) and normally open push button (NO switch) and normally close push button (NC switch. This will be the complete guide because the diagram which i design for the post is an animation diagram and every know the power of learning of animation diagram.
3 Phase Motor Wiring Diagram With Magnetic Contactor – Thermal Overload Relay – MCCB and Push button switches
The controlling and wiring connection of a 3 phase machine or motor is become easy after invention of magnetic contactor. Every one know that advantages of contactor . These cont actors are well know with name of motor stater. And by using this we can done many works and circuit which will not be possible with MC.
What is Magnetic Contactor and it’s working
Now come main point of this post . 3 phase wiring is very simple as i written in my above words. And this is very important for an electrical technology student. before i get start first see the below 3 phase motor wiring diagram and after that we will explain it step by step.
For complete understanding we do all connection step by step. First in above diagram i start form wiring connection of mccb circuit breaker. Why we use the circuit breaker that we also know that the we can switch on off the motor using magnetic contactor.
Note that magnetic contactor we use for switching on off the motor and MCCB circuit breaker use for controlling all the circuit. When we have any problem in the circuit and change a substance in circuit then we easily switch off the main supply by using the mccb breaker and can work easily and safely.
Now come to the next step, in step we connect the phase power source L1, L2, L3 to circuit breaker and form circuit breaker we will connect the magnetic contactor Main contacts. But note that this info is only for learning purpose and if you gonna to do this type of instillation then do the main circuit breaker connection in last. However for complete understanding i guide you step by step this circuit diagram.
So we connect the there phase supply (red, yellow, blue) to the main connects of magnetic contactor.
What’s MC and and how it’s working
After connecting supply to main contacts of motor stater/ MC then get connection of 3 phase lines for overload relay main contacts. We can use the thermal overload or electronic overload relay with motor to safe or switch off motor during over current flow.
Now come to the connection of motor, the above induction motor which i shown in the diagram is an delta connection. We use two types of connection in 3 phase motor star and delta and which we do it motor connection plate or connection points. These connection called star and delta connection. However the high wattage motor over up to 15 HP motor connection we do in star delta for which we use the star delta starters. However i will publish a post about this soon.
Come to the next and which called small wiring, in the above diagram i shown a contactor which coil rated or design for 440 volts , however MC are available in different types regarding it’s rated volts such as 12v, 24, 110v, 220, 440v. As we use a 440 volts coil MC then the first step to connect a line to coil 1 terminal which can be named with A1. I shown it my above diagram and i get connection for coil from MCCB L2 yellow wire.
In the MC we have main connects which is named with L1, L2 , L3 or T1 , T2 , T3 but we have some more contacts which may available on one side of MC or both sides. These called auxiliary contacts.
We also use the Push button switches in which the red is normally close and the green is normally open contacts. You can see it in my above diagram.
Now get connection from L3 wire form the load site of mccb and connect to the Normally close contacts of thermal overload relay which named with the name of 95 and 96, ( note that the 97 and 98 contacts in thermal overload relay is normally open contacts) Now if you connect the wire to 95 then get connection from 96 and connect to the normally close push button switch which is red switch.
Now after that get connection from the red push button switch and connect it to the normally open switch and which is green push button and this switch we use for stating motor and red switch for switching off motor.
Now provide the a wire form NC to NO switch but this wire will be control able form the NC switch. Now where you connect this wire, get a wire link for contactor normally open auxiliary contact as i shown in the above diagram.
The the next step to connect a wire between the other side from the auxiliary contacts terminal and connect to the NO switch as i shown in the above diagram and then from same place provide a wire connection to starter coil.
Note that this starter is also will know with name of direct online starter DOL.
Also read below
DOL Direct online starter wiring diagram explanation
In last do earth connection with motor frame body as i shown in the above diagram.
Before to do 3 phase motor wiring , start your work form Molded case circuit breaker . Then contactor , thermal overload or electronic relay and then to motor. But Do these all 3 phase motor wiring without electricity and when you done all the steps then provide the electric supply to the circuit breaker.
Now if you have any question regarding 3 phase motor wiring diagram or any suggestion then you can use the below comments section. Be safe. ALLAH HAFIZ.