Type: Pilot Wire Current Differential Feeder Protection Relay
Brand: Siemens Reyrolle
Model: 7PG21
Applications: Overhead lines, underground cables, interconnector circuits
Features:
Relays and CTs installed at both ends of the circuit, connected via dedicated pilot wires
Simple and robust design ensuring reliable operation
Three current inputs per relay, housed in E6 enclosures
High transient stability and fast fault detection
Adjustable phase and earth fault settings
Minimal variation of performance with pilot wire length
Optional 15 kV pilot isolation and supervision schemes
Test points available on relay fascia
Optional remote intertripping via pilot cores
Functions:
Protection: Three-phase differential protection via pilot wires
Supervision: Optional pilot wire supervision and overcurrent check
Control: Optional intertripping/unstabilising control
Compliance: IEC standards, Reyrolle Solkor R & Solkor Rf compatible
Mounting: Panel-mounted design
Maintenance: Easy installation, commissioning, and servicing
Protection Functions:
Distance protection with 6 measuring systems (21/21N)
High resistance earth-fault protection for single and three-phase tripping (50N, 51N, 67N)
Earth-fault detection in isolated and resonant-earthed networks
Tele (pilot) protection (85)
Fault locator (FL)
Power-swing detection/tripping (68/68T)
Phase-overcurrent protection (50/51)
Switch-onto-fault protection (50HS)
STUB bus overcurrent protection (50STUB)
Overvoltage/undervoltage protection (59/27)
Over/underfrequency protection (81O/U)
Auto-reclosure (79)
Synchro-check (25)
Breaker failure protection (50BF)
Thermal overload protection (49)
Control Functions:
Commands for control of circuit breakers and isolators
Monitoring Functions:
Trip circuit supervision (74TC)
Self-supervision of relay
Measured-value supervision
Event and fault logging
Oscillographic fault recording
Switching statistics
Front Design:
Easy numeric keypad operation
Function keys
LEDs for local alarm indication
Front PC port for DIGSI 4 configuration
Communication Interfaces:
Front interface for PC
System interface for control systems:
IEC 61850 Ethernet
IEC 60870-5-103 protocol
PROFIBUS-FMS / DP
DNP 3.0
Serial teleprotection interface
Rear service/modem interface
Time synchronization via IRIG-B, DCF77, or system interface
