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Sepam 80 Pole Slip (ANSI 78PS) protection - can it be used to replace a Vector Shift protection in Loss Of Mains applications?

Loss of Mains protection (LOM) is the requirement for the connection of Generation to the UK distribution network. Its role is to prevent the generator from accidentally energising an electrically isolated section of network. 
(Source: Beddoes, Thomas, and Austin)

Loss of Mains relays typically will provide Vector Shift protection, which is a function that can operate rapidly in response to an event.  Please see the attached file for an example of a relay which provides Vector Shift protection.

The question has been raised as to whether or not the Sepam 80 Pole Slip protection could be used to replace the Vector Shift function of a Loss Of Mains relay.

Historically, the Sepam marketing strategy has been to use the ROCOF (Rate of Change of Frequency) protection for Loss Of Mains applications, instead of the Vector Shift protection.  So, even going back to the now-obsolete Sepam 2000 relays, Sepam has never had a vector shift function.

If we consider the functionality of the Woodward relay, we can see that the vector shift protection operates quickly (i.e., within a few cycles).  In contrast, the Sepam 80 Pole Slip protection function needs at least a few cycles to detect power swings in the system.  The concept of the protection function is looking for different types of phenomena in the power system, and the operation time is not designed to be similar to that of the vector shift function.

Based on the points above, the conclusion is that the 78PS function on Sepam is not well-suited to replace the vector shift protection provided by the Woodward relay.  If you are looking for a Schneider product to use in this type of application, you may consider a MiCOM relay such as the P341 which does include the vector shift protection function.

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