Line current differential relay Siemens Power Transmission Distribution

The 7SD60 relay is a numerical current differential protection relay, simple to set, operating in conjunction with the remote station via a two pilot-wire link. It is connected to the primary current transformers via an external summation current transformer. The primary field of application of the relay is protection of short overhead lines and cables with two line ends. However, transformers and reactors may be located within the protection zone.


Function overview

• Current differential protection with external summation current transformer 4AM49

• Suitable for use for distances of 12 km max. via two pilot-wires

• Differential protection can be combined with overcurrent release

• Pilot-wire monitoring function

• Bidirectional remote tripping

• Circuit-breaker intertripping at the remote station

• Seal-in of the TRIP command until manual reset (Lockout function)

• Minimal current transformer requirements due to integrated saturation detector

• Restraint against inrush / undelayed trip for high differential fault currents

• Emergency overcurrent protection


Operational measured values

• Local and remote current

• Differential current

• Restraint current

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