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Introduction

1.3 Characteristics

SIPROTEC, 7SD5, Manual

C53000-G1176-C169-5, Release date 02.2011

Restricted earth fault protection

• Earth fault protection for earthed transformer windings

• Short tripping time

• High sensitivity for earth faults

• High stability against external earth faults using the magnitude and phase relationship of through-flowing

earth current

Tripping at Line Ends with no or Weak Infeed (optional)

• Possible in conjunction with teleprotection schemes

• Allows fast tripping at both line ends, even if there is no or only weak infeed available at one line end

• Phase segregated tripping and single-pole automatic reclosure is possible (version with single-phase trip-

ping)

External Direct and Remote Tripping

• Tripping at the local line end from an external device via a binary input

• Tripping of the remote line end by internal protection functions or an external device via a binary input (with

teleprotection)

Transmission of information

• Transmission of the measured values from all ends of the protected object with the magnitude and phase

• Transmission of up to 4 fast commands to all remote ends (order option)

• Transmission of up to 24 additional binary signals to all remote ends (order option)

Time Overcurrent Protection

• Selectable as emergency function during a failure of the main protection function(s) due to a failure of the

data communication and/or the measuring voltages, or as backup function

• Maximally three definite time stages (DT) and one inverse time stage (IDMT), each for phase currents and

for earth currents

• For inverse-time overcurrent protection a selection from various characteristics based on several standards

is possible

• Blocking capability e.g. for reverse interlocking with any stage;

• Instantaneous tripping by any stage when switching onto a fault

• End fault protection: fast tripping on faults between the current transformer and line isolator (when the iso-

lator switching status feed back is available); particularly well suited to substations with

circuit breaker

arrangements

High Current Switch-onto-Fault Protection

• Fast tripping for all faults on 100 % line length

• Selectable for manual closure or following each closure of the circuit breaker

• With integrated line energization detection.

Siemens SIPROTEC User Manual

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