Impedance relay- theory of operation

[mbrooke]

What is the theoretical principle (physics) behind how an impedance relay operates? Why is it that Z=V/I always seems to work regardless the bus "strength" ie, any given fault on a line may produce a small or large amount of voltage drop on a buss based on available generation/remote impedance connected to that bus? Would an impedance relay still work on an infinite buss? Is it possible to protect low reactance (jX) elements like LV cable or a series of resistors with an MHO impedance relay?


Apologies ahead of time if I am being vague or broad here.

 

[gar]

170116-0930 EST

Define what an impedance relay is and what it is supposed to do. How many input terminals are there and what do these connect to in the relay? How many output terminals are there and what do these come from in the relay?

Some general definitions for relay are:

https://www.merriam-webster.com/dictionary/relay

https://en.wikipedia.org/wiki/Relay

http://www.dictionary.com/browse/relay

.

 

[mbrooke]

170116-0930 EST

Define what an impedance relay is and what it is supposed to do. How many input terminals are there and what do these connect to in the relay? How many output terminals are there and what do these come from in the relay?

Some general definitions for relay are:

https://www.merriam-webster.com/dictionary/relay

https://en.wikipedia.org/wiki/Relay

http://www.dictionary.com/browse/relay

.

My mistake, being a bit vague. In simple terms what is known as step distance protection.


https://www.youtube.com/watch?v=rYU2s6tJ9Ck