Chapter 16 – Maintenance and Troubleshooting
2 MAINTENANCE
2.1 MAINTENANCE CHECKS
In view of the critical nature of the application, Alstom Grid products should be checked at regular intervals to
confirm they are operating correctly. Alstom Grid products are designed for a life in excess of 20 years.
The devices are self-supervising and so require less maintenance than earlier designs of protection devices.
Most problems will result in an alarm, indicating that remedial action should be taken. However, some
periodic tests should be carried out to ensure that they are functioning correctly and that the external wiring
is intact. It is the responsibility of the customer to define the interval between maintenance periods. If your
organisation has a Preventative Maintenance Policy, the recommended product checks should be included
in the regular program. Maintenance periods depend on many factors, such as:
The operating environment
The accessibility of the site
The amount of available manpower
The importance of the installation in the power system
The consequences of failure
Although some functionality checks can be performed from a remote location, these are predominantly
restricted to checking that the unit is measuring the applied currents and voltages accurately, and checking
the circuit breaker maintenance counters. For this reason, maintenance checks should also be performed
locally at the substation.
Before carrying out any work on the equipment you should be familiar with the contents of the
Safety Section and the ratings on the equipment’s rating label.
6.7.1 ALARMS
First check the alarm status LED to see if any alarm conditions exist. If so, press the Read key repeatedly to
step through the alarms.
After dealing with any problems, clear the alarms. This will clear the relevant LEDs.
6.7.2 MEASUREMENT ACCURACY
If the power system is energised, the measured values can be compared with known system values to check
that they are in the expected range. If they are within a set range, this indicates that the A/D conversion and
the calculations are being performed correctly.
Alternatively, the measured values can be checked against known values injected into the device using the
test block, (if fitted) or injected directly into the device's terminals..
2.2 REPLACING THE UNIT
If your product should develop a fault while in service, depending on the nature of the fault, the watchdog
contacts will change state and an alarm condition will be flagged. In the case of a fault, you should normally
replace the cradle which slides easily out of the case. This can be done without disturbing the scheme wiring.
In the unlikely event that the problem lies with the wiring and/or terminals, then you must replace the
complete device, rewire and re-commission the device.
If the repair is not performed by an approved service centre, the warranty will be invalidated.
To Next Page
Loading...