Alstom MiCOM P846, Technical Manual

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Programmable Logic P846/EN PL/D
MiCOM P846
(PL) 7-3
1. PROGRAMMABLE LOGIC
1.1 Overview
The purpose of the programmable scheme logic (PSL) is to allow the relay user to configure
an individual protection scheme to suit their own particular application. This is achieved
through the use of programmable logic gates and delay timers.
The input to the PSL is any combination of the status of opto inputs. It is also used to assign
the mapping of functions to the opto inputs and output contacts, the outputs of the protection
elements, e.g. protection starts and trips, and the outputs of the fixed protection scheme
logic. The fixed scheme logic provides the relay’s standard protection schemes. The PSL
itself consists of software logic gates and timers. The logic gates can be programmed to
perform a range of different logic functions and can accept any number of inputs. The timers
are used either to create a programmable delay, and/or to condition the logic outputs, e.g. to
create a pulse of fixed duration on the output regardless of the length of the pulse on the
input. The outputs of the PSL are the LEDs on the front panel of the relay and the output
contacts at the rear.
The execution of the PSL logic is event driven; the logic is processed whenever any of its
inputs change, for example as a result of a change in one of the digital input signals or a trip
output from a protection element. Also, only the part of the PSL logic that is affected by the
particular input change that has occurred is processed. This reduces the amount of
processing time that is used by the PSL; even with large, complex PSL schemes the relay
trip time will not lengthen.
This system provides flexibility for the user to create their own scheme logic design.
However, it also means that the PSL can be configured into a very complex system, hence
setting of the PSL is implemented through the PC support package S1.
Note: Each setting group has its own PSL. Once a PSL has been designed
it can be sent to any one of 4 setting groups within the relay. When
downloading a PSL to the relay the user will be prompted to enter the
desired setting group to which it will be sent. If the user fails to
download the required PSL to any setting group that may be brought
into service, then factory default PSL will still be resident and this may
have severe operational and safety consequences.
PL
1.2 S1 Px40 PSL editor
To access the Px40 PSL Editor menu click on
The PSL Editor module enables you to connect to any MiCOM ALSTOM device front port,
retrieve and edit its Programmable Scheme Logic files and send the modified file back to a
Px40 device.