The RASC synchronism-check relay is used to permit circuit breaker closing only when the measured voltage phasors on either side of an open circuit breaker are within prescribed limits of magnitude, phase angle and frequency. Synchronism-check relays are used to supervise the manual or automatic closing control circuits of circuit breakers where synchronism is established elsewhere on the power system.
The RASC synchronism-check relay is a modular design built up of the following functional units:
- Test switch RTXP 18
- Dc-dc converter RXTUG 22H
- Measuring unit RXNAA 4
- Pulse unit RXNAB 2H
- Voltage check unit RXNAC 2H
- Output relay RXME 1
Main Features:
- Measures the difference in magnitude, phase angle and frequency of two voltage phasors
- Three versions available, each having a fixed frequency difference sensitivity
- Four modules available with respect to rated voltage, each with two reconnectible values of rated voltage
- Available with or without voltage check unit for dead line or bus check
- One of the two voltage inputs designed with extra low burden for connection to CT capacitive taps
- Provides continuous or pulse output
- Two make and two break heavy-duty output contacts
- Includes test switch