Where can we use directional relay? and what is its types?

directional relay use to protect bus bar-generators -transformer and it's used with over current relay and there are two types of it

1 - the type that used with over current relay this type separates after reverse the current  and increase the power of the rated current

Instantaneous directional relay--2

This method is often used with over current relayThread is protecting the region by the relay of the occurrence of any mis (fault) in the circuitWe find that in the normal state in the current passes in the normal direction of the circle , but in case of any (fault) , the current trend is reflected passes in the direction of the relay  who shall separate the C.B. And there are two types of the directional relay:1 - the type used with over current relay this type separates after reflection and increase the power of the rated currentInstantaneous directional relay -2This type separates after intraday trend reversal which is used to protect the generator in his condition and the presence of two generators on the same bus bar