Automatic Star-Triangle Switch / Star-Triangle Time Relay

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

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

Description and principle of operation

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

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

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

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

• After the time t1 has elapsed, the STAR contact is disconnected, the light goes off and a short pause t2 (15 ms) starts.

• Subsequently, the PHASE-TRIANGLE contacts are switched on, the TRIANGLE indicator lights up and the relay remains in this mode for the entire time that 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 with high demands for stable and safe motor starting

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

Complementary range

For the relay you can purchase:

• contactors and starters

• contactors with mechanical interlocking

• stand-alone mechanical interlock modules

• metal enclosures with IP65 protection

All this is available directly from stock at competitive prices.