Automatic star-delta switch/star-delta time relay

Relay for star and delta start modes (ERV-YU)

The ERV-YU starter relay is designed to automatically control the starting of electric motors in star-delta start mode, with an operating voltage of 24/220 V AC. The relay ensures a smooth motor start, reduces inrush 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 setting the start time.

Description and operating principle

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

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

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

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

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

• Subsequently, the phase and delta contacts are engaged, the delta indicator lights up, and the relay remains in this mode as long as voltage is supplied to the A1-A2 terminals.

Application

The ERV-YU relay is suitable for:

• automatic motor switching control in star and delta mode

• industrial applications where high requirements are placed on stable and safe motor starting

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

Additional assortment

You can purchase the following with the relay:

• contactors and starters

• contactors with mechanical interlock

• separate mechanical interlock modules

• metal enclosures with IP65 protection

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