RET615 is a special transformer control and protection device designed to protect double-winding transformers, block and step-up transformers, including generator-transformer blocks of power plants and energy facilities. The RET620 / 630 is a dedicated transformer control device for the protection, control, measurement and monitoring of two-winding power and step-up transformers, including generator-transformer units, in power plants and utility distribution networks.
The control device provides the main differential protection of the transformer, has one stage with braking (several characteristics) and a cut-off, providing fast selective protection in case of phase-to-phase faults, protection against turn-to-turn faults and short-circuit of the busbar. There is also a choice of low-impedance or high-impedance braking earth fault (REF) protection.
The device is ideal for voltage regulation. The voltage regulator is designed for power transformers with an on-load tap-changer, which has a motor drive, and allows both manual and automatic control.