7SA511 Line Protection Relay

 

Acceptance Tests

Validity

X

Validity range KX

range KR

X+A

 

 

 

 

 

VP

ø p

Ip

R

RA RAE

 

X-A

Validity range KX

Validity

range KR

 

Figure 3-2.Polygonal Impedance Fault Detection Characteristic.

Determine the threshold point by slowly reducing the voltage. Check indicators and outputs. Since the fault detection polygon is made up of straight lines (Figure 3-2), different formulas must be used for the threshold voltages dependent upon the intersections of these lines. The general formulas are:

For the reactance intersections (X-reach)

VP/V = KXX± A (IP/IN)

For the resistance intersections (R-limitation)

VP/V = KRRA(IP/IN)

3-20

July 27, 1995

Page 46
Image 46
Siemens 7SA511 manual Vp/V = Krraip/In