Siemens Siprotec 4 SIPROTEC 7SD5 Protection Relay

The SIPROTEC 7SD5 Protection Relay provides full scheme differential protection and incorporates all functions usually required for the protection of power lines. It is designed for all power and distribution levels and protects lines with two up to six line ends. The relay is designed to provide high-speed and phase-selective fault clearance.

The relay uses fiber-optic cables or digital communication networks to exchange telegrams and includes special features for the use in multiplexed communication networks. Also, pilot wires connections can be used with an external converter. This contributes toward improved reliability and availability of the electrical power system. The relay is suitable for single and three-phase tripping applications for two up to six line ends.Also, transformers and compensation coils within the differential protection zone are protected as are serial and parallel-compensated lines and cables.

The relays may be employed with any type of system grounding. The relay also provides a full-scheme and non-switched distance protection as an optional main 2 protection. Several tele protection schemes ensure maximum selectivity and high-speed tripping time. The units measure the delay time in the communication networks and adaptively match their measurements accordingly. A special GPS-option allows the use of the relays in communication networks, where the delay time in the transmit and receive path may be quite different.

The 7SD5 has the following features:-2 full-scheme main protections in one unit (differential and distance protection)-High-speed tripping 10 15 ms-The serial protection interfaces (R2R interfaces) of the relays can flexibly be adapted to the requirements of all communication media available.-If the communication method is changed, flexible retrofitting of communication modules to the existing configuration is possible.-Tolerates loss of one data connection in a ring topology (routing in 120 ms). The differential protection scheme is fully available in a chain topology.-Tolerates loss of one data connection in a ring topology (routing in 120 ms). The differential protection scheme is fully available in a chain topology.-Browser-based commissioning tool.-Fault locator for one and two terminal measurements for high accuracy on long lines with high load and high fault resistance.-Capacitive charge current compensation increases the sensitivity of the differential protection on cables and long lines.

SIPROTEC 7SD5 RELAY PROTECTION FUNCTIONS

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

SIPROTEC 7SD5 RELAY CONTROL FUNCTIONS

• Commands for control of circuit-breakers (isolators)

MONITORING FUNCTIONS

• Self-supervision of relay and protection data (R2R) communication
• Trip circuit supervision (74TC)
• Measured-value supervision
• Oscillographic fault recording
• Event logging/fault logging
• Switching statistics

FRONT DESIGN

• User-friendly local operation
• PC front port for relay setting
• Function keys and 14 LEDs f. local alarm

COMMUNICATION INTERFACES

• 2 serial protection data (R2R) interfaces for ring and chain topology
• Front interface for connecting a PC
• System interface for connection to a control system via various protocols
  – IEC 61850 Ethernet
  – IEC 60870-5-103
  – PROFIBUS-FMS/-DP and DNP 3.0
• Rear-side service/modem interface
• Time synchronization via IRIG-B or DCF77 or system interface

SIPROTEC 4 leads the way in integrating protection, control, measurement, and automation functions in one device. The homogenous system platform, the unique DIGSI 4 engineering program, and extensive experience of more than a million successfully operating devices in the field worldwide – thanks to these unique advantages, SIPROTEC 4 enjoys top recognition among users worldwide. SIPROTEC 4 is the industry standard for digital protection technology today in all fields of application.