Automatic star-delta switch / star-delta time relay

Relay for star-delta starting modes (ERV-YU)

The ERV-YU starting relay is designed for automatic control of starting electric motors in the STAR-DELTA mode at an operating voltage of 24/220 V AC. The relay ensures a gentle start of the motor, reduces the starting current, and extends the lifespan of the entire drive system. It is equipped with light indicators for the modes ON, STAR, and DELTA and allows the starting time to be set.

Description and operating principle

For a smooth start of the electric motor, the STAR mode is first activated, which reduces the initial current peak. When the required speed is reached, the winding is automatically switched to the DELTA mode, in which the motor continues to operate normally.

Automatic mode switching by relay and switches increases the stability of the entire system and eliminates the risks associated with manual operation.

When voltage is applied to the terminals A1-A2 of the relay:

• The STAR contact is activated, the STAR indicator lights up, and the starting interval t1 (0.1-30 s) begins to count.

• After the time t1 has elapsed, the STAR contact is broken, the light goes out, and a short pause t2 (15 ms) begins.

• Then the PHASE-DELTA contacts are switched on, the DELTA light turns on, and the relay remains in this mode for as long as voltage is applied to the terminals A1-A2.

Use

The ERV-YU relay is suitable for:

• automatic control of motor circuits in star-delta mode

• industrial applications with high demands for stable and safe motor starting

• systems where it is necessary to reduce starting current and protect the electrical network

Additional range

For the relay, you can purchase the following

• magnetic switches and starters

• magnetic switches with mechanical locking

• stand-alone mechanical locking modules

• metal enclosures with IP65 protection

All of this is available directly from stock at competitive prices.