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I am in the process of cordinating time-overcurrent curves for a 115/4.16kV(15MVA-55c, 28MVA-65c) transformer. I have a GE F35 Relay on the high side of my transformer and I have a GE F35 Relay on the low side breaker. At full load amps the XFMR will put out 3886 amps on 4.16kV side but the...

I am trying to calculate the fault current on the low side of a transformer. The Transformer parameters are 69kV high side to 12.47kV low side, 40/55/67MVA, 11% impedance. With all of this said how does the X/R ratio figured into the equation? And what is the "K" factor of a transformer?

I am in the process of trying to calculated a transmission line impedance for the purpose of distance protection. I do not have any software to model the line and was wondering if there was a more straight forward(real world) method of calculating the impedance without having to use the...

I am in the process of sizing current transformers for a 20MVA 69kv-4.16kv power transformer. I am calculating the 69kV full load current to be 167amps and the 4.16kV full load current to be 2776amps. The low side current transformer will be used for differential protection. Can anyone...

I am in the process of setting an SEL 279 relay. Does anyone know any good rules of thumb for the 25D setting? I have seen ranges from 17 cycles to 120 cycles. The setting is developed from a formula in the SEL manual that depends on "slip frequency" and "closing angle". Please help.

What is Generator Islanding? I have heard several relay engineers talk about triping generators out and they always refer to islanding. Does anyone know what they are talking about?

Hello, my name is Brandon. I have designed numerous protection schemes for ring-bus switchyards. There are a couple of books that go into general protection schemes but I am not sure how specific they get into ring-bus configurations. They are, 1. Protective Relaying Theory and Applications -...

I am trying to open a file with the extension .cal Does anyone know what program I need to be in to open this?

What is a FLOWGATE