Siemens 7SA511 manual Directional Protection With Nondirectional Backup

7SA511 Line Protection Relay Chapter 5

Each type of high-resistance ground fault protection, listed below, is discussed separately in this section.

Directional, definite time overcurrent protection with nondirectional backup element. The settings for this type of protection are in address block 3100.

Directional, definite time overcurrent protection with directional comparison and nondirectional backup element. The settings for this type of protection are in address

￿blocks 3100 and 3200.

Nondirectional, inverse time overcurrent protection element. The settings for this type of protection are in address block 3300.

The various high-resistance ground fault protection methods are described in detail in Reference A, “Method of Operation.”

High-resistance ground fault protection for grounded systems can also work with the automatic reclose function, when available. Refer to section 5.16 for information on programming the relay for automatic reclose operations with high-resistance ground fault protection.

5.15.1 Directional Protection With Nondirectional Backup (3100)

For directional, definite time overcurrent protection with nondirectional backup, the parameters are set in address block 3100. Table 5-23 lists the relay presettings and setting options available. Compare these presettings to the information on the completed worksheets and determine which settings you need to change to match your operating environment. When you have changed all of the necessary settings, follow the procedure described in section 5.3.4 to save the new settings.

Prerequisite Settings:

Addr.	LCD Text
7808	EARTH FAULT
1102	SYSTEMSTAR

Description

Type of ground fault protection

System neutral condition

Setting

DIRECTIONAL D.T. SOLIDLY EARTHED

July 27, 1995 5-39