Siemens 7SA511 manual Setting value X of the distance zone to be checked

7SA511 Line Protection Relay Acceptance Tests

Feed a test current IP = 2IN into the loop under test. If the test voltage will exceed the rated

voltage when the threshold is reached, reduce the test current (the minimum current I > at

ph

address 1621 or 1621 and overcurrent Iph>> at address 1601 must still be exceeded). The test current must be kept constant during a test.

X

Validity range KX

X

Vp

		Validity range KR
φp
Ip	R	RE
		R
45°

Figure 3-3.Distance Zone Characteristics.

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

For the reactance intersections (X-reach)

VP/V = KXXZone(IP/IN)

For the resistance intersections (R-limitation)

	VP/V = KRRZone(IP/IN)
where	IP	- test current
	IN	- rated relay current
	VP	- test voltage at threshold
	XZone	- setting value X of the distance zone to be checked
	RZone	- setting value R or RE of the distance zone to be checked
	KX	- factor for X intersection according to Table 3-18
	KR	- factor for R intersection according to Table 3-18

3-22 July 27, 1995