Relay Directionality Demonstrator (Enhanced)

Polarization Methods: Choose how the relay determines direction.

Positive sequence voltage (V1) polarizes, positive sequence current (I1) operates.

This is the standard method for phase fault detection. It works by comparing the angle between positive sequence voltage and current.

When I1 is within ±90° of V1 (adjusted by MTA), the relay determines forward direction.

Zero sequence voltage (-3V0) polarizes, zero sequence current (3I0) operates.

This is the primary method for ground fault detection. The negative sign on -3V0 aligns the polarizing quantity with expected fault direction.

The factor of 3 compensates for the sequence network calculations, making quantities comparable to phase values.

Negative sequence voltage (V2) polarizes, negative sequence current (I2) operates.

Used for sensitive ground fault detection and specific unbalanced fault conditions.

More sensitive than zero sequence for some ground faults and can detect high-resistance faults.

Quadrature voltage (Vbc = Vb-Vc) polarizes, phase A current (Ia) operates.

Common for phase distance elements, providing memory voltage during close-in faults.

The quadrature relationship (90° shift) between Vbc and Ia in normal system conditions provides good discrimination.

Polarization Method

V1 Pol / I1 Op (-3V0) Pol / (3I0) Op V2 Pol / I2 Op Vbc Pol / Ia Op

Relay Settings

MTA: -45°

Min Op: 0.10pu

Char. Diam: 2.00pu

Relay Directionality Toolkit by Doug Millner of NERX Power Consultants LLC

Voltages

V1 Mag: 1.00

V1 Ang: 0°

V2 Mag: 0.00

V2 Ang: 0°

V0 Mag: 0.00

V0 Ang: 0°

Currents

I1 Mag: 1.00

I1 Ang: 330°

I2 Mag: 0.00

I2 Ang: 0°

I0 Mag: 0.00

I0 Ang: 0°

Phase Voltages

Phase Currents

POLARIZED