The Voltage Protection Relay (VPR-A) has been designed to measure the line or phase RMS voltages under normal conditions or under disturbances. This information is internally processed by the microprocessor, to take the voltage protection actions defined under ANSI or IEC standards. The different functions provided by the VPR-A may be classified into the following groups:
- Protection of generators, motors and transformers against adverse system voltage conditions.
- Supervision of automatic transfer switching schemes.
- Selection of protection curves a definite time.
- Timed and instantaneous undervoltage (ANSI 27t/27i).
- Residual undervoltage (ANSI 27r).
- Timed and instantaneous overvoltage (ANSI 59t/59i).
- Homopolar overvoltage (ANSI 59N).
- Voltage unbalance (ANSI 46).
- Overfrequency and underfrequency (ANSI 81).
- Phase reversal (ANSI 47).
- Five (5) output relay programmable.
- Loss of control volts relay.
- RMS line or phase voltages.
- Line or phase voltage unbalance.
- Average voltage.
- Supply frequency.
- Phase sequence.
Signaling and Programming:
- LED and LCD display indication.
- Touchpad programming.
- Indication and storage of fault conditions and their values.
- Undervoltage/overvoltage/unbalance/frequency pickup indicators for calibration testing