To start and close the three-phase AC import motor, any three-stroke replacement at the appropriate current level will suffice. Just turning off such a switch to send three-phase power to the car will cause it to start, while turning on a three-stroke switch will reduce the power of the car to turn it off.

If we wish to have a remote start and stop control of three-phase vehicles, we need a special relay with alternating cables large enough to safely drive the car flow over multiple start and stop cycles. The large, high-performance electromechanical transmission designed for this purpose is often referred to as industry contacts.

Schematic diagram

A schematic diagram of a three-phase connector connected to a third-phase vehicle (with overprotected fuses) is shown here:

The A1 and A2 power stations power the electromagnet coil, causing all three switch contacts to simultaneously shut off, transmitting three-phase AC power to the car. Re-energizing the coil causes it to de-magnetize, disassemble the weapon and enable the return spring inside the contact to touch all three contacts in the open (closed) area.


The estimated 75 horsepower (480 volt AC 3-phase) power is shown here, both combined with the top cover removed to set three sets of high-power switch contacts:


Each phase connection is actually a pair of series of contacts that make and break simultaneously with the operation of the metal arm attracted by the electromagnet coil at the base of the communication assembly.

The main electrical terminals (L1-L3, T1-T3) in this contact hide two small screw terminals (commonly called A1 and A2) that provide connecting points to the electromagnet coil that transmits the contact:

Like most three-phase connectors, this coil is rated at 120 volts of AC. Although the electric car can operate in three phases, the 480 volt AC power, the communication coil and all other control cycles operate on low power for safety reasons.

Like all electromechanical transmissions, automotive contacts use a low-power signal to control high-voltage power lines.

This “amplification” action enables small control switches, in comparison, and transmission circuits to start and stop large (high-volume) electric motors.

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