Star-delta automatic switch / Star-delta timed relay

Relay for Star-Delta Starting Modes (ERV-YU)

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

Description and Operating Principle

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

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

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

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

• After the time t1 elapses, the STAR contact is turned off, the indicator light goes out, and a short pause t2 (15 ms) starts.

• Subsequently, the PHASE-DELTA contacts are closed, the DELTA indicator lights up, and the relay remains in this mode as long as voltage is applied to terminals A1-A2.

Usage

The ERV-YU relay is suitable for:

• Automatic control of motor switching in star-delta mode

• Industrial applications requiring stable and safe motor starting

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

Complementary Range

For the relay, you can purchase

• contactors and starters

• contactors with mechanical interlocking

• standalone mechanical interlocking modules

• metal enclosures with IP65 protection

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