Answer: Directional relay must have the following features :
1. High speed operation
2. High sensitivity
3. Advocate short time
4. Thermal rating
5. Ability to operate with low values of voltage burden must not be excessive and
6. There should be no voltage and current creep.
Directional Relay: Directional relay operates when the fault is driving power to flow in particular direction. It senses the direction of current flowing. For example, consider a three phase synchronous motor. Assume fault on the system. Power supply to motor is not available. But 3-phase armature is rotating in magnetic field due to inertia. So motor starts generating power. Which feeds fault. To avoid this, Directional Relay is used.