• Emco Electronics

Voltage Regulating Relay

Emco Electronics offers solid-state automatic Voltage Regulating Relay, type EE 301-M, designed for operational simplicity. It regulates the secondary voltage of power transformers with on-load tapchangers. The bandwidth control allows the deadband to be set in terms of upper (lower volts) and lower (upper volts) voltage limits around a particular nominal value with specified sensitivity. The time delay control allows the regulator to respond only to the voltage fluctuations lasting for periods greater than the selected time delay. Where the voltage correction requires more than one tap change, the time delay is re-initiated before further tap changes. No special provision is required to reset the time delay, which resets automatically after the voltage correction. For repeated short duration voltage fluctuations on the same side of the dead-band, the time delay is effectively reduced to provide a voltage time integral response of the regulator. Solid-state lamps (LEDs) indicate voltages outside the preset limits and control relay operations. Operation of the raise control relay is automatically inhibited when the voltage falls below the specified undervoltage limit. One pair of normally open relay contacts is provided to effect the tapchanger raise and lower operations and to trigger an alarm in case of under voltage conditions. The electronic circuitry of the relay is mounted on plug-in cards so that for servicing or inspection they can be withdrawn from the case (which is fixed in the control panel cut-out) without disturbing the connections to the relay terminal. For compensating line resistance and reactance at different load currents an optional line drop compensator can be provided in the same cabinet. An alarm in case of auxiliary supply failure can also be provided in the form of normally close contacts in the same cabinet. Also an alarm in the form of normally open contacts can be provided in the same cabinet in case of control failure, i.e., AVR relay continuously showing either 'L' or 'R' command for more than 15 minutes due to malfunctioning of AVR/OLTC/any other reason.