P54x/EN OP/La4 Operation
(OP) 5-168
MiCOM P543, P544, P545 & P546
OP
5. DUAL CIRCUIT BREAKER CONTROL : P544/P546 OPERATIONAL
DESCRIPTION
This section describes the P544/P546 operational control of dual circuit breakers.
5.1 INTRODUCTION
The ci
rcuit breaker control and monitoring in the dual-breaker P544/P546 provides single
phase or three phase switching of a feeder controlled by two circuit breakers at a line end,
for example in a one and a half switch configuration or at a mesh type (ring bus) installation.
It can also be set to manage switching of a feeder controlled by a single circuit breaker
This section introduces the operation of the circuit breaker scheme. It describes the circuit
breaker state monitoring, condition monitoring, circuit breaker control, and the circuit breaker
auto-reclose operation.
The control of dual circuit breaker switching sequences represents a complex logic
arrangement. The operation is best understood by reference to the design logic diagrams
that have been used to implement the functionality. For ease of reference, all these logic
diagrams have been put together in a supplementary section “P544/P546 Circuit Breaker
Control and Auto-Reclose Figures” section (AR figures) at the end of this chapter. Any
figures that are not explicitly presented in this chapter will be found in the AR figures section
and will be clearly indicated.
The inputs and outputs of the logic described are, in many cases, DDB signals that are
available to the programmable scheme logic (PSL). A description of these signals can be
found in the programmable logic chapter (P54x/EN PL) of this manual. Other signals are
also used to define the operation but are internal to the logic of the circuit breaker control.
Unlike the DDB signals, these internal signals cannot be accessed using the programmable
scheme logic. They are hard-coded into the application software. A second supplementary
section lists these signals and provides a brief description to aid understanding.
5.2 Circuit breaker scheme designation (P544/P546)
In the dual-breaker P54
4/P546, the two controlled circuit breakers are designated CB1 and
CB2. CB1 connects the P544/P546 to Bus1 and CB2 connects the P544/P546 to Bus 2.
It is possible to configure the P544/P546 for use in a single circuit breaker application using
either CB1 control or CB2 control. If operating like this, all text, etc., associated with the
unused circuit breaker is hidden.
Note: In some of the menu text, the reference to which circuit breaker is
being described, is not explicitly stated (for example, CB Operations
in the circuit breaker monitoring features). In all such cases, an
unqualified CB reference should be assumed to be associated
with CB1. CB2 is always used to explicitly indicate CB2. An
unqualified CB or an explicit CB1 refers to CB1. CBx indicates either
CB1 or CB2.
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