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raghun (Electrical)
9 May 07 10:45
The relay P241 is a commonly used one and not much of problems reported. P243 with more functionality than P241, includes additional functions such as Motor differential protection and more I/Os.

The complaint being faced during commisioning of the motor with motor protection relay-P243 is that the Undervoltage element doesn't reset when the CB is open and even after the motor CB is closed and the voltage to relay is more than the U/V pick up setting.

Did any one come across similar issues with the relay P243! Could it be that the processor in the relay is not able to support adequately the huge functionality!

Thanks in anticipation.
riteshbharat (Electrical)
9 May 07 17:47
I doubt that the processor would be incapable of handling multiple functions. There are many other MiCOM models, which use the same processor and perform much more complex algorithms. I believe it could be something to do with the PSL. If you back trace the output relay which is picking up, you may get some clue.
raghun (Electrical)
10 May 07 2:13
riteshbharat,

Thnks for the response. The PSL has been checked by us and subsequently by AREVA engineers when the issue was referred to them. The PSL is OK.

AREVA, UK is yet to come back with a solution. Meanwhile I thought I can bounce the issue in this forum to see any one else has similar issues with the particular type P243. As I said, P241 doesn't pose any problems (we have been using the P241s for many years now.
raghun (Electrical)
30 Jun 07 9:30
The problem with the relay P243 is identified and rectified as below. This is to share with you all.

Thanks for the support again.

"Recently two problems have been highlighted related to the P243 Motor Protection relay.
1.  Trip command active before motor starting.
2.  Failure of Inhibit (undervoltage) during motor starting.
 
Description Of Problem and Root cause:
The problem came to light during commissioning activities and can be summarised as follows:
 
The problem results in the relay maintaining a trip command for an undervoltage condition where this condition exists prior to an attempted motor start. The Inhibit function during start function was also ineffective as a result of the problem and the motor therefore fails to start.
The problem has been investigated by Areva  and simulated in the laborartory. The root cause of the problem was a flaw in the software in the memory allocation reserved for protection tasks. This meant that certain variables became overwritten and the problem. The software has therefore been modified to increase the memory allocation and to prevent this from occurring, therefore, new firmware had to be installed to resolve the problem."
ScottyUK (Electrical)
30 Jun 07 11:43
Thanks for the update raghun. Do you know what Areva's stance is regarding this relay: Is this error in the software present in all P243s? Are they proposing to offer an EPROM update to those users affected, and at whose expense?
 

----------------------------------
  Sometimes I only open my mouth to swap feet...

raghun (Electrical)
3 Jul 07 5:00
ScottyUK,
AREVA have upgraded the relay software as indicated in my above post (even for the relays already in the field).

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