Application Notes; Scheme Reconfiguration; Alarm Management; Alarm Logic - GE P4A Technical Manual

P54A/B/C/E
5

APPLICATION NOTES

Effective communications are essential for the performance of teleprotection schemes. Disturbances on the
communications links need to be detected and reported so that appropriate actions can be taken to ensure that
the power system does not go unprotected.
5.1

SCHEME RECONFIGURATION

Each relay of the Multi-Ended Line Differential scheme has a reconfiguration feature. This feature allows a relay to
be put 'Out of Service' for maintenance or testing purposes. This can be achieved by toggling the Re-Configuration
option under PROT COMMS/IM64 from Disabled to Terminal N, where N is the end to be taken out of service
(A-F).
This affects the overall scheme in the following way:
● The communication channels of the 'reconfigured' relay remain in service. This means there is no
interruption to the ring communication or loss of redundancy
● The current (load) values of the reconfigured terminal relay are not included in the idiff and ibias calculations
by other relays in the scheme
The following should be taken into consideration during reconfiguration:
Only one relay end can be reconfigured in a scheme at a given time
●
● A minimum of 3 terminals need to remain in service after reconfiguration
The Reconfiguration Interlock DDB must be asserted before the relay is reconfigured
●
Any terminal of the scheme can be used to send a reconfiguration command to another terminal that is required
to be taken out of service. The relay will get 'reconfiguration confirmation' from all ends. Testing can then be
carried out on the relay that is out of service.
5.2

ALARM MANAGEMENT

Due to the criticality of IM64 communications for correct scheme performance, there is an extensive regime to
monitor signal quality and integrity, generate and report alarms. For most applications, the alarm management
provided as standard will satisfy the needs of the scheme.
For some applications, it may be necessary customise the alarm management. You can do this with the
programmable scheme logic. This section provides a detailed explanation the communications alarm signals
integrated in this product.
5.3

ALARM LOGIC

The figures in the logic diagram section show the main alarm DDB signals associated with IM64. Some of the
signals are setting or hardware dependent. For example, Channel 2 alarms are not available on a simple two-
terminal single communications link application. This section explains the logic, allowing you to understand how
you might customise the alarm logic for your application.
P54xMED-TM-EN-1
PROT COMMS/ IM64
Re-Configuration
Disabled
PROT COMMS/ IM64
Re-Configuration
Terminal B
Chapter 15 - Fibre Teleprotection
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