Alstom MiCOM P546 - 5. TWO CIRCUIT BREAKER CONTOL (P446) WORKED EXAMPLE; 5.1 Introduction

Application Notes P54x/EN AP/La4
MiCOM P543, P544, P545 & P546
(AP) 6-77
AP
5. TWO CIRCUIT BREAKER CONTOL (P446) WORKED EXAMPLE
A worked example of the control of a feeder switched by a dual circuit breaker is presented
below. Detailed explanation of the control of such a scheme is presented in the operations
chapter (P54x/EN/OP) of this manual.
5.1 Introduction
This ap
plication example is for two shot, single and three phase, auto-reclosing at one end of
an EHV (500 kV) overhead transmission line switched by two circuit breakers in a one and a
half switch configuration.
The single line diagram for the circuit is shown below in Figure 27
This exa
mple outlines the settings required for auto-reclosing using a MiCOM P544 or P546
relay at sub-station A.
Line 1
Bus 1
Line 2
P54x
1
Live VT
CB3
CB2
CB1
VT
VT
Bus 2
1
Sub-Station A
3
P4344ENb
Figure 27 Two circuit breaker auto-reclose application
Auto-reclosing is considered to be initiated by differential protection, by distance protection
tripping for a fault in Zone 1 or by aided high speed tripping. It is also possible to initiate
auto-reclose by an external protection device, in which case the auto-reclose initiation would
be provided by an opto input.
The circuit breakers are capable of either single phase or three phase tripping. Circuit
breaker 1 (CB1) is designated as Leader and will reclose before Circuit breaker 2 (CB2).
CB2 becomes the designated Follower, and will reclose after a Follower Time delay after
CB1 has successfully reclosed.
The Leader, CB1 is arranged for single/three phase tripping and reclosing. The Follower,
CB2 is arranged to trip three phase for all faults.