7SA511 Line Protection Relay

Commissioning the Relay

X

Positive reactive power

ZLoad

Direction

characteristicForwards

Active power

R

~45°

Reverse

Negative reactive power

ZLoad = Pactive + Preactive

I2I2

Figure 7-1.Load Impedance Vector.

7.3.3 Checking the Carrier Transmission System

The following functions are checked as part of this test process:

Overreach zone comparison via pilot wires

Reverse interlocking

Carrier transmission with release signal

Carrier transmission with blocking signal

￿Carrier transmission with underreach transfer signal

Carrier transmission for directional comparison ground fault protection

All of the equipment associated with transmission of signals should be commissioned in accordance with the documentation provided for that equipment.

Overreach Zone Comparison Via Pilot Wires

The overreaching zone comparison operating mode differs fundamentally from the other pilot protection systems in its transmission method (DC current, fail-safe loop). Skip this section if a different pilot protection method is used.

The line protection devices at both line ends must be in operation. At first the auxiliary voltage for the fail-safe current loop around the pilot wires should not be switched on.

7-8

July 27, 1995

Page 162
Image 162
Siemens 7SA511 manual Checking the Carrier Transmission System, Overreach Zone Comparison Via Pilot Wires