CT magnetization Current effect on REF Relay Protection

Hi Sir,

We have REF protection for our transformer and REF relay is voltage setting type relay and set at 55v as per calculation ( Reyroll 5B3 relay). At the time of Factory Test all the CTs ( R,Y,B,N) were showing magnetization current of .026 Amps @ 120Volts & .01 Amps at 60Volts as per CT rating ( CT rating : 2500/5A, Class PX, Knee voltage 120V 7 magnetization current at 120 V is 0.024 Amps). Now the panel is under operation. Recently transformer REF tripped and we investigated and couldn't find any fault but we noticed that Nuetral CT is showing magnetization current of  .068 Amps @ 120Volts  and all other Cts at showing 0.026 @ 120V. This could be the reason for tripping?. Please let me know this magnetization current will effect the REF relay operation?.

Out Transformer is 1600KVA, 11KV/415 Volts. Impedance 5.6%, CT resistance is 0.65 ohms and CT loop resistance is  0.02 ohms.


asked 12/27/2017

2 Answers

Oh man I am so disappointed I visited your site to check any updates for San Jose Del Cabo as I needed this on urgent basis.
answered 5 months ago Davina Seto 2
Davina Seto
I think I need a proper understand of the specific terms to completely understand and some  uk.superiorpapers.com review might be able to assist me on such matters.
answered 6/9/2018 IrvinJones 2

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