Σi*-Method Stage; Description - Siemens 6MD85 Manual

Siprotec 5 high-voltage bay controller

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Table of Contents

Measured Values, Energy Values, and Supervision of the Primary System

9.6 Circuit-Breaker Wear Monitoring

ΣI*-Method Stage

Logic of the Stage

[LoCBWIxS, 3, en_US]

Determination of the Tripping/Opening Current Value

RMS values of the fundamental components are stored for each phase in a buffer during the time between the

start criterion and the pole-opening-starts criterion. With the coming pole-opening-starts criterion, the latest

value in the buffer is searched for whose value is above the setting of parameter Current thresh. CB

open. The 20 ms prior value is used as tripping/opening current for further calculation.

If no value within the buffer is above the setting value, this circuit-breaker opening affects only the mechan-

ical lifetime of the circuit breaker and is consequently not considered by this method.

Logic of the ΣI

-Method Stage

SIPROTEC 5, High-Voltage Bay Controller, Manual

C53000-G5040-C015-9, Edition 11.2017