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ON / OFF 3-Phase Motor Using 11-PIN Relay and DOL Starter

How to Start and Stop a Three-Phase Motor using 11-PIN PLA Relay and DOL Starter?

There are various methods for controlling, starting, and stopping three-phase motors, such as Star-Delta Starter, DOL starter, PLC, and VFD-based methods etc. In today’s tutorial, we will demonstrate how to start and stop a 3-phase motor using an 11-PIN relay and a DOL Starter (based on a contactor and thermal overload relay) with the help of wiring, power and control circuit diagrams.

A Direct-On-Line (DOL) starter (consists of a contactor, thermal overload relay) is a widely used method to start and stop three-phase motors while an 11-PIN relay is an electromechanical switch designed to control various functions within a circuit.

Components Required

To create an ON/OFF control circuit for a three-phase motor using an 11-PIN relay and a DOL starter, the following components are needed:

  1. Three-Phase Motor
  2. 11-PIN PLA Relay
  3. DOL Starter (based on Contactor & Thermal Overload Relay)
  4. 2-MCB and 3-P MCCB
  5. Control Switches (Start “NO” and Stop “NC”)
  6. 3 NO of polit light indictors
  7. Single Phase & Three Phase Supply
  8. Wires & Cables

Wiring the Power and Control Circuit

Follow these steps to properly wire the circuit for controlling the ON/OFF operation of a three-phase motor using an 11-PIN relay and a DOL starter as shown in the following wiring, power and control diagram.

ON-OFF 3-Phase Motor Using 11-PIN Relay & DOL Starter

    1. Connect the three-phase supply of 415VAC via a 3-P MCCB to the 1L1, 3L2, and 5L3 terminals of the Contactor, O/L relay (2T1, 4T2, 6T3) , and then the 3-Phase motor (U1, V1 & W1) respectively (wiring DOL Starter).
    2. Connect the phase (line) wire from 2P-MCB to the 95-NC and 98-NO terminals of the overload relay
    3. Connect two pushbuttons in series (RED-NC to Stop and Green-NO to Start) from the 96-NC terminal of the overload relay. Then, connect the output terminal of the NO-pushbutton to the 1st terminal of Red pilot light indictor, A1 terminal of contactor and 2 (Line) and 3-NO terminals of the 11-PIN relay respectively as shown in fig.
    4. Wire a jumper from the output of the Red-NC (Stop) push button (or the starting point of the Green-NO switch) to the 6-NC and 5-COM terminals of the PLA relay.
    5. Connect the 1-COM terminal of the PLA relay to the 1st terminal of Green pilot light indictor.
    6. Now, wire the 1st terminal of Yellow/Orange pilot light indictor to the 97-NO terminal of O/L Relay.
    7. Finally, connect the neutral wire from the MCB to the A2 terminal of the contactor, 2nd terminals of all three indicators and the 10 terminal of the 11-PIN relay.
    8. Finally, properly ground the motor, DOL starter, and control circuit to ensure safety.

Working of Starting & Stopping 3-Phase Motor using 11-PIN Relay & Contactor

  1. When the Motor is not running, the Green Indicator (connected through 11COM and direct 8NC) is glowing which indicates the motor is stop.
  2. Pressing the start button energizes the relay’s coil, which activates the DOL starter’s contactor.
  3. This way, the NC becomes NO and vice versa. But the holding wire (to 3-NO & 8-NC) makes sure continuous latching circuit i.e. removing the pressure from Green (Starting) pushbutton won’t stop the circuit.
  4. When the 11-Pin relay activates, its 3-NO becomes 3-NC with 1COM and 2-L which complete the circuit and activate the contactor connected to the O/L relay and 3-Phase motor. 
  5. The DOL starter connects the motor windings directly to the three-phase power supply, initiating the motor’s start-up sequence. Hence, the Red Indicator ON which indicates the motor is running.
  6. The motor accelerates to its rated speed.
  7. Pressing the stop button de-energizes the relay’s coil and holdover the holding circuit to the initial state, deactivating the motor’s starter. The motor comes to a stop.
  8. The yellow/orange indicator only glows when the circuit trips due to overloading.

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