Warning: An open circuit of the CT secondary wiring can cause high voltage
which may be lethal and could damage insulation.
• Optionally external supply can be wired to the relay aux. supply terminals with proper polarity
marking as mentioned on the Terminal sticker at the back of the relay. The supply range is also
mentioned on this sticker. Confirm that the auxiliary supply is in range before energizing the
relay.
• Trip Coil contact connection should be as per the given schematic diagram.
• Latching type annunciation contact connection as per requirement of site.
2.2.2.1 Earthing
An earthing terminal is provided at the back of the relay. Ensure that the case earthing connections
(Top right-hand corner at the rear of the IED case) are used to connect the IED to a local earth bar
using an adequate conductor.
With several relays present, make sure that the copper earth bar is properly installed for solidity
connecting to the earthing terminal of each relay.
2.2.2.2 CT Polarity
Ensure proper CTs are connected as per required maximum load current and their polarity. When all
CTs are connected with proper polarity, unbalance current flowing through earth fault element will be
approximately zero. Otherwise the relay will trip on earth fault when the CB is energized.
2.2.3 Check relay settings
The relay setting check ensures that all of the application-specific settings for the particular installation
have been correctly applied to the relay. Enter all settings manually via the front panel interface or
suing P50 Agile configurator tool.
Following points to be checked:
• Ensure overcurrent and earth fault trip setting.
• Ensure TMS setting of overcurrent and earth fault are entered correctly as per required time
grading between feeder and incomer.
• Ensure instantaneous setting is correct and its definite time delay is applied properly as per
required time grading between feeder and incomer.
• Ensure selection of latching type annunciation duty contact is as per required function.
• Ensure that the current measurement in the relay is same as the applied current .
2.2.4 Final check
After completion of all relay functionality testing and relay setting check, remove all test equipment and
shorting leads and then restore all the original wiring from the relay. While restoring wiring, it should be
ensured that the CT connections are restored in accordance with the relevant external connection or
schemes diagram. Ensure all fault and annunciation contacts, and trip contacts have been reset
before leaving relay.
If the P15D is newly installed or the CB has just been maintained, the trip counter of Relay should be
zero. This counter can be reset by enabling Clear Faults function in the RECORD CONTROL menu.
Note: This will also clear all fault memory and the set password.
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