Siemens 7SA511 manual Automatic Reclose optional, Distance-to-Fault Location

7SA511 Line Protection Relay Product Description

2.4.7 Automatic Reclose (optional)

Automatic reclose (AR) is an optional relay function (relay models 7SA511*-**A5*-

**B/C/F/G*). The automatic reclose function can minimize the system down time caused by temporary faults. The range of functions for automatic reclose include:

Three-pole automatic reclose for all fault types

Single-pole automatic reclose for single-phase faults, no reclose for multi-phase faults Single-pole automatic reclose for single-phase faults, and three-pole automatic reclose for multi-phase faults

Single- or multi-shot reclose On/off control

Selection of which protection elements can initiate automatic reclose Programmable reclaim time after

successful AR cycle unsuccessful AR cycle manual reclose of circuit breaker

Integration with external automatic reclose equipment with communications via binary inputs and outputs

￿Control of the automatic reclose function by an external protection scheme Blocking of automatic reclose

following manual reclose

-on reverse direction fault detection (user-programmable) on detection of evolving faults (user-programmable)

2.4.8 Distance-to-Fault Location

The distance-to-fault location function provides quick location of the fault point and repair of any resultant damage, which increases the availability of the line for energy transmission in the system. Distance-to-fault location is typically initiated by a trip command from the distance protection function, but it can also be initiated by a binary input.

Working independently from the distance protection elements, distance-to-fault uses its own filter algorithms and measured values to recognize and locate the fault. The fault location calculation results in the following outputs:

Short circuit loop from which the fault reactance is determined

Reactance per phase in primary ohms

Resistance per phase in primary ohms

￿Distance to the fault in unit-of-length measure Distance to the fault in percent of total line length

For accurate impedance measurements in parallel line systems, the optional ground fault detection function for parallel line compensation is required (relay models 7SA511*-**A5*-2***).

2-12 July 27, 1995