Siemens 7SA511 manual Overview of Protection Functions, Distance Protection, Feature, Description

7SA511 Line Protection Relay Product Description

Address

8200

8500

LCD Text

RESET

PARAMETER CHANGE-OVER

Description

Reset stored data including the LEDs, event log, and target log data.

Select which parameter set is to be active, and copy parameter sets.

2.4 Overview of Protection Functions

This section gives an overview of each of the 7SA511 relay protection functions, as listed below:

Distance protection

Emergency overcurrent protection

Power swing protection (optional)

Pilot protection

Ground fault detection for ungrounded systems (optional)

High-resistance ground fault protection for grounded systems (optional)

￿Automatic reclose (optional) Distance-to-fault location

You should read the relay’s model number on the front of the operator panel to determine if your relay has the optional protection functions. section 1.3 in the “Introduction” section of this manual describes how to read and interpret the relay model number.

2.4.1 Distance Protection

Distance protection is the main function of the 7SA511 relay. It is characterized by high measuring accuracy and flexible adaptation possibilities for the system characteristics. The distinguishing distance protection features of the 7SA511 relay are briefly discussed in the rest of this section.

Feature

Fault detection options

Description

Overcurrent fault detection (Iph>>). Use of this fault detection

￿scheme depends on high short circuit currents.

Voltage-controlled overcurrent (underimpedance) fault detection (V</I>). An overcurrent detection scheme in which the pickup value is voltage-controlled. The measured voltages, depending on the selected settings, may be the phase-to-ground or the phase-to-phase voltages.

Polygonal impedance (dogbone) fault detection (Z<). This detection scheme uses calculated loop impedance values.

2-8 July 27, 1995