3 phase motor contactor wiring diagram:

This diagram shows how to make 3 phase motor contactor wiring diagram. In this circuit, we use a TP MCB ( Tripple Pole Minature Circuit Breaker ), a magnetic contactor, a start switch, a stop button, and a three-phase motor. This circuit is very simple and easy to make. If you want to know more about this circuit please check our youtube video below the post. 


Diagram of 3 phase motor contactor wiring diagram:

3 phase motor contactor wiring diagram

Components needed For this Project:

You can get the components from any of the sites below:

  1. TP MCB 32A [See Buy Click Amazon]
  2. Magnetic Contactor 40A [See Buy Click Amazon]
  3. 3 Phase Motor (5 HP) [See Buy Click Amazon]
  4. Push Button NO Switch [See Buy Click Amazon]
  5. Push Button NC Switch [See Buy Click Amazon]

*Please note: These are affiliate links. I may make a commission if you buy the components through these links. I would appreciate your support in this way!

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Components used to make the 3 phase motor contactor wiring diagram:

01. TP MCB:

The full meaning of MCB is Miniature Circuit Breaker for TP MCB. MCB is an electromagnetic switch or device. If for any reason a short circuit occurs in the supply line or load line (line to line or line to neutral) or in case of overload MCB. the MCB automatically trips and disconnects the main line circuit or household power supply Connection. TP MCB In 3 Pole MCB, Switching & Protection is affected in only 3-Phases and the Neutral is not part of the MCB. 3 pole MCB signifies the Connection of Three Wires for a 3-Phase system Red-Yellow-Blue Phase. 3-Phase Supply Only Without Neutral.

02. Magnetic Contactor:

A magnetic contactor is an electromagnetic switching device. It is generally used for controlling 3-phase Motors. The operation of a magnetic contactor is similar to that of a Relay. but a relay is used for low-power or low-voltage connections, and a magnetic contactor is used for high-power or high-voltage connections. As soon as the supply is applied to the magnetic contactor coil. its normally open contacts are closed and normally closed contacts are opened and the associated devices are also operated. This is how a magnetic contactor works.

03. 3 Phase Motor:

A 3-phase electric motor uses a 3-phase Power Supply to Convert Electric Energy into Mechanical Energy. It contains four Wires (Three hot Wires and one Neutral Wire) and Uses 3 Alternating Currents of the Same Frequency. Since it Generates a Rotating Magnetic Field, it does not need a Capacitor for the Startup. Some 3-phase Motors are Reversible, Which Means they can serve as Generators by Turning Mechanical Energy into Electrical Energy.

04. Start Button:

NO (Normally Open) Terms Refer to a Type of Dry Contact or Wet Contact. A Push to Make Switch Allows Electricity to flow Between its 2 contacts when held in. When the button is released, the Circuit is broken. This type of Switch is also known as A Normally Open (NO) Switching system. As its name implies, a Normally Open (NO) Switch Contact or “a Contact” is a Switch. Put very simply, a Normally Open Sensor will have no Current When in a Normal State But When it Enters an Alarm State it will have +5V applied to the Circuit.

05. Stop Button:

An NC (Normally Closed) Push Button is a Push Button That, In Its Default State, Makes Electrical Contact With The Circuit. An NC (Normally Closed) Push Button is a Push Button that, in its Default State, Makes electrical Contact With the Circuit. When The Button Is Pressed Down, The Switch no Longer Makes Electrical Contact And The Circuit is Now Open. When The Button is Not Pressed, Electricity Can Flow, But When it is Pressed The Circuit is Broken. This type Of Switch is Also known As a Normally Closed (NC) Switch.

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Frequently asked questions

How does a 3-phase motor contactor work?

Motor contactors work by controlling the circuit diagram to connect or disconnect the load from the supply. This is done by energizing the coil which in turn closes the power supply contacts to supply power to the load or de-energizing the coil which opens the contact or disconnects the power to the load.

What is 3 phase contactor?

Perhaps the most common of the industrial use for contactors is the control of electric motors. The top 3 contacts switch the respective phases of the incoming 3-phase AC power supply, typically at least 480 Volts for motors 1 horsepower and greater.

How can you test a 3-phase motor?

For 3 phase motor use an ohm meter and measure the resistance between each LEG or lead The resistance should be all the same. For 1ph winding, it will have a start and a run winding. The start wdg has a higher resistance than the run of the wdg. Each motor is different so there is no set of the values.

What are the common problems found in a 3-phase motor?

The main types of external faults experienced by these motor pumps are overloading, single phasing, unbalanced supply voltage, locked rotor, phase reversal, ground fault, under voltage, or over-voltage. The machine would be shut down when a fault is experienced to avoid damage or for the safety of the workers.

What causes a 3-phase motor to run slow?

If the motor's internal connection is a multi-circuit diagram, it will start but will have a reduced power supply. An open circuit diagram will cause the magnetic circuit to be unbalanced. Thus, under normal load, the motor will run more slowly or will overheat.

Read more Single Phase Wiring


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