Which is an overcurrent relay with directional restraint?

Classification of distance relay

1.) Reactance relay

• This relay is used for the protection of short transmission lines.
• The reactance relay is independent of the resistance value.
• A reactance relay is an overcurrent relay with directional restraint. 
• The directional element is arranged to develop maximum negative torque when its current lags its voltage by 90°.

2.) Impedance relay

• This relay is used for the protection of medium transmission lines.
• An impedance relay is a voltage-restrained overcurrent relay.
• This relay operates when the impedance seen from the source to the faulty point is less than the relay setting.

3.) Mho relay 

• This relay is used for the protection of long transmission lines.
• This relay is least affected by power surges.
• An mho relay is a voltage-restrained directional relay.