Distance Protection
General Information
- Description
In meshed networks, distance protection is the central protection function in the feeder protection. SIPROTEC distance protection relays feature different starting criteria and extensive additional functions, achieve short tripping times, a high network stability, also in the fault case, as well as a high network availability by means of extensive auto-reclosure functions.
7SA522
Distance Protection Relay for Transmission Lines
- Description
- Function overview
The SIPROTEC 4 7SA522 relay provides full-scheme distance protection and incorporates all functions usually required for the protection of a power line. The relay is designed to provide fast and selective fault clearance on transmission and subtransmission cables and overhead lines with or without series capacitor compensation. The power system star point can be solid or resistance grounded (earthed), resonant-earthed via Peterson coil or isolated. The 7SA522 is suitable for single-pole and three-pole tripping applications with and without tele (pilot) protection schemes.
The 7SA522 incorporates several protective functions usually required for transmission line protection.
- High-speed tripping time
- Suitable for cables and overhead lines with or without series capacitor compensation
- Self-setting power swing detection for frequencies up to 7 Hz
- Digital relay-to-relay communication for two and three terminal topologies
- Adaptive auto-reclosure (ADT)
Protection functions
- Non-switched distance protection with 6 measuring systems (21/21N)
- High resistance ground (earth)-fault protection for single and three-phase tripping (50N, 51N, 67N)
- Tele (pilot) protection (85)
- Fault locator (FL)
- Power swing detection / tripping (68/68T)
- Phase-overcurrent protection (50/51)
- STUB bus overcurrent protection (50STUB)
- Switch-onto-fault protection (50HS)
- Over/undervoltage protection (59/27)
- Over/underfrequency protection (81O/U)
- Auto-reclosure (79)
- Synchro-check (25)
- Circuit-breaker failure protection (50BF)
Control functions
- Commands for control of CB and isolators
Monitoring functions
- Trip circuit supervision (74TC)
- Self-supervision of the relay
- Measured-value supervision
- Event logging/fault logging
- Oscillographic fault recording
- Switching statistics
Front design
- User-friendly local operation with numeric keys
- LEDs for local alarm
- PC front port for convenient relay setting
- Function keys
Communication interfaces
- Front interface for connecting a PC
- System interface for connecting to a control system via various protocols
- IEC 61850 Ethernet
- IEC 60870-5-103 protocol
- PROFIBUS-FMS/-DP
- DNP 3.0 - 2 serial protection data interfaces for tele (pilot) protection
- Rear-side service/modem interface
- Time synchronisation via IRIG B or DCF77 or system interface
Hardware
- Binary inputs: 8/16/22/24
- Output relays: 16/24/32/44
- High-speed trip outputs: 5 (optional)
Standards
