Hitachi Relion 650 Series Technical Manual page 92

Section 9
Control
reference signal, the function needs to evaluate optimal switching instants to close the CB at point D.
The breaker operating time (from point A to C) is a property of each CB pole; the predicted operating
times are received from other functions. Hence, the function needs to calculate this additional time
delay required to reach point D.
The calculated time delay is a function of various components such as the latest zero crossing
the current making target, pre-arcing time, mechanical operating time, environmental factor
compensation, adaptive correction of target errors, and breaker scatter correction. Starting from the
latest received voltage zero crossing, as displayed in
the electrical (target) making instant X by adding the current making target.
Latest zero
crossing
IEC19000900 V2 EN-US
Figure 41:
The current making target for each phase (relative to a positive-going voltage zero crossing in the
same phase) is defined using the equations:
Current making target
Current making target
zero crossing of phase L2),
Current making target
zero crossing of phase L3)
The target making instant X is obtained by extrapolating future zero crossings (using the received
average half cycle time) and selecting a reachable one, that is, farther in the future than the expected
mechanical closing time. From that, the mechanical closing instant Y is achieved by adding the
predicted pre-arcing time (PPREARCLx input) to the instant X. The breaker release instant is defined
using the equation:
Breaker release instant = Y − (Mech operating time + miscellaneous compensation)
where,
Mech operating time = INPRICLLx input value
Y = X + PPREARCLx,
miscellaneous compensation = COMPOFCLx + ADAPTCLx + SCATOFLx input values
where,
COMPOFCLx is the total compensation of environmental factors affecting CB closing time;
ADAPTCLx is the adaptive correction value for previous targeting errors;
[1] Latest zero crossing is the last zero crossing seen by the function prior to activation of the function CMDCLOSE input.
86
Breaker release
instant
ZC
Input
command
Evaluation of controlled closing switching instants
= CloseTargetL1,
L1
= CloseTargetL1 + CloseTargetL2-L1 –120° (based on the positive-going
L2
= CloseTargetL1 + CloseTargetL3-L1 – 240° (based on the positive-going
L3
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Figure 41 the function further moves ahead to
X
Y
Time
Current making
Pre-arcing
target time
Mech operating time +
miscellaneous compensation
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[1]
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