Automatic star-delta switch / star-delta timer relay

Star-Delta Starting Mode Relay (ERV-YU)

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

Description and Principle of Operation

For a smooth electric motor start, the STAR mode is activated first, which reduces the initial current surge. Once the required speed is reached, the winding automatically switches to TRIANGLE mode, where the motor continues to operate normally.

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

When voltage is applied to the A1-A2 terminals 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 time t1 has elapsed, the STAR contact disconnects, the indicator turns off, and a short pause t2 (15 ms) begins.

• Next, the PHASE-TRIANGLE contacts connect, the TRIANGLE indicator lights up, and the relay remains in this mode for the entire time voltage is applied to the A1-A2 terminals.

Usage

The ERV-YU relay is suitable for:

• automatic control of motor switching in star-delta mode

• industrial applications with high demands for stability and safety in motor starting

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

Complementary Range

You can purchase for the relay

• contactors and starters

• contactors with mechanical interlock

• standalone mechanical interlock modules

• metal boxes with IP65 protection

All available directly from stock at competitive prices.