Table 70. Tap changer control with voltage regulator (OLATCC)
Characteristic
Value
Operation accuracy
1)
Depending on the frequency of the current measured: f
n
±2 Hz
Differential voltage U
d
= ± 0.5% of the measured value or ± 0.005 x U
n
(in measured voltages < 2.0 x U
n
)
Operation value = ± 1.5% of the U
d
for Us = 1.0 x U
n
Operate time accuracy in definite time mode
2)
+ 4.0% / - 0% of the set value
Operate time accuracy in inverse time mode
2)
+ 8.5% / - 0% of the set value
(at theoretical B in range of 1.1…5.0)
Also note fixed minimum operate time (IDMT) 1 s.
Reset ratio for control operation
Reset ratio for analogue based blockings (except run back raise
voltage blocking)
Typical 0.80 (1.20)
Typical 0.96 (1.04)
1)
Default setting values used
2)
Voltage before deviation = set Band center voltage.
Transformer Protection and Control
1MRS757846 A
RET620
Product version: 2.0
42
ABB
