CM
1. INTRODUCTION
The P74x Busbar Differential Protection is fully numerical in their design, implementing all
protection and non-protection functions in software. The relays employ a high degree of self-
checking and, in the unlikely event of a failure, will give an alarm. As a result the
commissioning tests do not need to be as extensive as with non-numeric electronic or
electromechanical relays.
To commission numerical relays, it is only necessary to verify that the hardware is
functioning correctly and the application-specific software settings have been applied to the
relay (PSL, topology, differential and breaker failure protection linked to the topology/PSL). It
is considered unnecessary to test every function of the relay if the settings have been
verified by one of the following methods:
− Extracting the settings applied to the relay using appropriate setting software
(preferred method) such as S1
− Via the operator interface.
Unless previously agreed to the contrary, the customer will be responsible for determining
the application-specific settings to be applied to the relay and for testing of any scheme logic
applied by external wiring and/or configuration of the relay’s internal programmable scheme
logic.
Blank commissioning test and setting records are provided at the end of this chapter for
completion as required.
As the relay’s menu language is user-selectable, it is acceptable for the Commissioning
Engineer to change it to allow accurate testing as long as the menu is restored to the
customer’s preferred language on completion.
To simplify the specifying of menu cell locations in these Commissioning Instructions, they
will be given in the form [courier reference: COLUMN HEADING, Cell Text]. For example,
the cell for selecting the menu language (first cell under the column heading) is located in the
System Data column (column 00) so it would be given as [SYSTEM DATA, Language].
Before carrying out any work on the equipment, the user should be familiar with the
contents of the safety section/safety guide Pxxx-SG-4LM-2 or later issue, the technical
data section and the ratings on the equipment rating label.
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