Controlled Switching And Monitoring; Introduction; Operation Principle - Hitachi Relion 650 Series Technical Manual

1MRK 511 557-UEN Rev. A
Section 7
7.1

Introduction

The function blocks described in this section are at the core of the controlled switching functionality.
These function blocks have strong interdependency and are combined in this section to explain the
concept and the functional interactions.
Controlled switching (also known as point-on-wave switching or synchronous switching) is defined as
controlling the circuit breaker in such a manner that the instant of current inception (on closing) or
contact separation (on opening) occurs at an instant that is optimal for the circuit breaker, the load,
and/or power quality.
A Switchsync PWC600 IED controls the instants at which the circuit breaker operates, monitors the
switching operation and logs the monitored data. To achieve this, various function blocks perform
specific functionalities; they are listed in
Table 21: Core application functions in PWC600
Function name Description
ANSGPROC
SSCPOW
ACBMSCBR
TRAFOSWT (PWC600-
HT only)
OPERLOG,
OPLOGTRIG
This section explains the operation principle from the product user's view point.
7.2

Operation principle

A random instant of switching the circuit breaker might impact the load, power system or circuit
breaker contacts because of high voltage or current transients or re-ignitions/re-strikes in the CB.
Conversely, controlled switching of the circuit breaker can avoid harmful transients in the network
and also increase the life time of the circuit breaker and/or the switched load.
The selection of the target phase angles for energization (making targets) depends on the basic
capacitive or reactive nature of the load. Capacitive loads should be energized at voltage zero across
the circuit breaker. This switching strategy ensures low inrush currents and low transient voltages.
Refer Equation 1

i C
GUID-54E449BA-4A65-447C-9803-1F589D393DE1 V2 EN-US
Technical Manual

Controlled Switching and Monitoring

Controlled switching is not a category of function blocks in PCM600 and LHMI.
Extracts zero crossings, amplitudes, and half cycle
times from reference voltage and current signals
Determines and releases controlled switching
commands to the circuit breaker
Monitors switching operation of the circuit breaker
Calculates residual fluxes and derives optimal
energization targets for power transformer
Stores monitored data in the operation log database
for relation of voltage across the capacitive load and current through it.
dv

dt
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Table 21.
Instances in pre-
configuration
1
1
3 (one per phase)
1
12+1
Section 7
Controlled Switching and Monitoring
GUID-7B9D8386-0CCA-4AB9-92E3-DE05405A0405 v3
Function category in
PCM600, LHMI, WHMI
Basic IED functions
Control
Monitoring
Monitoring
Monitoring
GUID-87EB84D8-3AC2-466B-A323-FBB5FB9477D6 v3
(Equation 1)
59