KD Relay

Application:• Compensator distance relay

that provides a single zone of phase protection for all three phases.

• It provides tripping for phase to phase, two phase to ground and three phase faults within the reach setting and sensitivity level of the relay

KD Relay Construction

Cylinder Unit:• Main function is to

operate when the angle between two signal applied is within certain range.

• Widely used as a directional unit and in impedance relays.

KD Relay ConstructionCylinder Unit:

• T=KI1I2SIN(Ø12-Ø)-KS

• Where K and Ø are design constants.

• Different combinations of input quantities can be used for different applications, system voltages or currents or network voltages.

•

KD Relay ConstructionCompensator:• Designated as T• Current to Voltage air

gap transformer.• Voltage side has a tap

which divides the winding in two sections.

• The output voltage angle can be changed by connecting a resistor across one of the voltage winding sections

KD Relay Construction

Compensator:

KD Relay

KD Relay

Operation:

KD Relay

KD Relay

C3C Capacitor

KD Relay

Impedance Circle

KD Relay

Impedance Curve

KD Relay

KD RELAY Equations needed for testing

M

STZSetting

1

•Impedance measured by 3 phase unit

L

LL

I

VZr

3Setting

LLL

Z

VI

3

Relay Setting

Used to find required test current

•Impedance measured by 2 phase unit

L

LL

I

VZr

2 Setting

LLL Z

VI

2 Used to find required test current

Tests Required

• Main tests required are the compensator check, maximum torque angle and the impedance test for 3 phase unit and phase to phase units.