For IDMT curve testing : Set IN >1 = 20%, TMS = 1.0
For DT curve testing : Set IN>1 = 20% Time delay =1 sec
Note: You can use only one CT input and Operating curves which is relevant to your
requirement.
Injected current Operating Time
For 1A
relay
For 5A
relay
IEC E
Inverse
IEC V
Inverse
IEC S
Inverse1
IEC S
Inverse2
DT
EF 5 In 1.0A 5.0A
5 In 5A 25A
For IDMT curve testing : Set IN >1 = 20%, TMS = 0.1
For DT curve testing : Set IN>1 = 20% Time delay =0.05 sec
Note: IDMT operating time should be 1/10 of above observed timing.
Injected current Operating Time
For 1A For 5A IEC E IEC V IEC S IEC S DT
EF 5 In 1.0A 5.0A
Note: The test results need to be compared with the technical claims stated in the manual.
2.3 Maintenance
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.
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
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