Siemens Siprotec 7UM611 Manual page 73

The value for I2> is set at Address 1702. It is at the same time the pickup value for a
Pickup Threshold /
current warning stage whose delay time T WARN is set at address 1703.
Warning Stage
Example:
Negative Sequence If the machine manufacturer has indicated the loadability duration due to an unbal-
Factor K anced load by means of the constant K = (I
FACTOR K. The constant K is proportional to the admissible energy loss.
Conversion to Sec- The factor K can be derived from the unbalanced load characteristic according to the
ondary Values following figure by reading the time at point I
Example:
t
The constant K
mary side).
The factor K
formula:
The calculated asymmetry factor K
Example:
I
I
Factor K
Setting value at address 1704:
7UM61 Manual
C53000-G1176-C127-3
2.10 Unbalanced Load (Negative Sequence) Protection (ANSI 46)
Machine I
N Mach
I
2 perm prim
Current transform- I
N CT prim
er
Setting value I
2 adm.
= 20 s for I /I = 1
adm 2 N
= 20 s determined in this way is valid for the machine side (pri-
primary
can be converted to the secondary side by means of the following
primary
= 483 A
N Mach
= 500 A
N CT prim
= 20 s
primary
= 483 A
/ I = 11 % permanent (salient-pole machine,
N Mach
see Figure 2-18)
= 500 A
= 11 % · (483 A/500 A) = 10.6 %
2
/I ) · t, it is set directly at address1704
2 N
= 1, corresponding to FACTOR K .
/I
2 N
is set as FACTOR K at address 1704.
sec
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