Main Function: Overcurrent and motor protection (backup protection for transformer differential relays)
Protection Functions:
Overcurrent (50/51/50N/51N)
Directional ground fault (67N/67Ns)
Motor protection: thermal overload (49), locked rotor (14), restart inhibit (66/86), load jam (51M)
Voltage & frequency protection (27/59, 81O/U)
Breaker failure (50BF), unbalance load (46), undercurrent (37)
Hardware:
4 current transformer inputs
0/3 voltage transformer inputs
3–7 binary inputs, 5–8 binary outputs
0–5 RTD inputs, 1 life contact
USB front port, removable terminals
Optional conformal coating
Communication:
IEC 61850 Ed. 1 & 2, IEC 60870-5-103, DNP 3.0, PROFIBUS-DP, MODBUS RTU
Ethernet redundancy (RSTP, PRP, HSR)
Millisecond-accurate SNTP time sync
Monitoring:
Voltage, current, frequency, breaker wear, trip supervision, fuse failure
Motor statistics and energy metering
8 oscillographic fault records
Applications:
Feeder, motor, and transformer backup protection
Industrial and utility substations
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
