SIEMENS SIPROTEC 4 SIPROTEC 7SD5 PROTECTION RELAY

Product Description

The 7SD5 relay providesfull scheme differential protection and incorporates all functions usually requiredfor the protection of power lines. It is designed for all power anddistribution levels and protects lines with two up to six line ends. The relayis designed to provide high-speed and phase-selective fault clearance. Therelay uses fiber-optic cables or digital communication networks to exchangetelegrams and includes special features for the use in multiplexedcommunication networks. Also, pilot wires connections can be used with anexternal converter. This contributes toward improved reliability andavailability of the electrical power system. The relay is suitable for singleand three-phase tripping applications for two up to six line ends.Also,transformers and compensation coils within the differential protection zone areprotected as are serial and parallel-compensated lines and cables.

The relays may be employedwith any type of system grounding. The relay also provides a full-scheme andnon-switched distance protection as an optional main 2 protection. Several teleprotection schemes ensure maximum selectivity and high-speed tripping time. Theunits measure the delay time in the communication networks and adaptively matchtheir measurements accordingly. A special GPS-option allows the use of therelays in communication networks, where the delay time in the transmit andreceive path may be quite different.The 7SD5 has the following features:-2full-scheme main protections in one unit (differential and distanceprotection)-High-speed tripping 10 15 ms-The serial protection interfaces (R2Rinterfaces) of the relays can flexibly be adapted to the requirements of allcommunication media available.-If the communication method is changed, flexibleretrofitting of communication modules to the existing configuration ispossible.-Tolerates loss of one data connection in a ring topology (routing in120 ms). The differential protection scheme is fully available in a chaintopology.-Tolerates loss of one data connection in a ring topology (routing in120 ms). The differential protection scheme is fully available in a chaintopology.-Browser-based commissioning tool.-Fault locator for one and twoterminal measurements for high accuracy on long lines with high load and highfault resistance.-Capacitive charge current compensation increases thesensitivity of the differential protection on cables and long lines.

PROTECTION FUNCTIONS

1. Differential protection with phase segregated measurement (87L, 87T)
2. Restricted ground-fault protection (87N) if a transformer is within the protection zone
3. Sensitive measuring stage for high-resistance faults
4. Non-switched distance protection with 6 measuring systems (21/21N)
5. High resistance ground (earth)-fault protection for single and three-pole tripping (50N/51N/67N)
6. Phase-selective intertripping (85)
7. Ground-fault detection in isolated and resonant-grounded networks
8. Tele (pilot) protection (85/21, 85/67N)
9. Weak-infeed protection (27WI)
10. Fault locator (FL)
11. Power swing detection/tripping (68/68T)
12. 3-stage overcurrent protection (50, 50N, 51, 51N)
13. STUB bus protection (50 STUB)
14. Switch-onto-fault protection (50HS)
15. Over/undervoltage protection (59/27)
16. Over/underfrequency protection (81O/U)
17. Auto-reclosure (79), Synchro-check (25)
18. Breaker failure protection (50BF)
19. Overload protection (49)
20. Lockout function (86)

CONTROL FUNCTIONS

1. Commands for control of circuit-breakers (isolators)

MONITORING FUNCTIONS

1. Self-supervision of relay and protection data (R2R) communication
2. Trip circuit supervision (74TC)
3. Measured-value supervision
4. Oscillographic fault recording
5. Event logging/fault logging
6. Switching statistics

FRONT DESIGN

1.    2.    3.     

COMMUNICATION INTERFACES

1. 2 serial protection data (R2R) interfaces for ring and chain topology