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Siprotec 7SD5 relay

Siprotec 7SD5 relay
Siprotec 7SD5 relay
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Product Code : SIP7
Brand Name : SIEMENS
Product Description

The 7SD5 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. 

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.

Protection Functions

  • Differential protection with phase segregated 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 inter-tripping (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/under voltage protection (59/27)
  • Over/under frequency protection (81O/U)
  • Auto-reclosure (79), Synchro-check (25)
  • Breaker failure protection (50BF)
  • Overload protection (49)
  • Lockout function (86)

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
  • Time metering of operating hours
  • Oscillographic fault recording
  • Event logging/fault logging
  • Switching Statistics


Office No.-9, Plot 53/54, Sector-34, Space Heights, Near Tawa Hotel, Kamothe, Navi Mumbai - 410209, Maharashtra, India
Mr Piyush Lalchand Rathi (Partner)
Mobile :+919819614841, +919769207841
Mr. Dnyanesh Gawande (Partner)
Mobile :+919833686249