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BUENO ELECTRIC
BUENO ELECTRIC
BUENO ELECTRIC
BUENO ELECTRIC
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Fax: +86-25-51816989
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character should be set to be KG1.10
＝
1
，
with setting value of “zero-sequence current 1” and “zero-sequence time
1”. Because this zero-sequence TA shares one input channel with phase B measurement, at this time, the device
could not measure phase B current.
When zero-sequence current is larger than setting “zero-sequence current 1” and reaches setting time
“zero-sequence time 1”, output trip would operate or alarm signal would be sent. The operation modes could be
selected through control character.
When control character KG1.10
＝
0, the zero-sequence current protection function would be shutdown, and the
measuring function of phase B measurement current of this channel would be realized.
The linear range of second type zero-sequence TA is
（
0.10A
～
20.00A
）
, input through terminal 2X:7
～
2X:8.
The zero-sequence current protection setting of this channel is determined by “zero-sequence current 2” and
“zero-sequence time 2”.
When input zero-sequence current is larger than setting “zero-sequence current 2” and reaches setting time of
“zero-sequence time 2”, output trip would operate.
4.6 Negative-sequence current element
Negative-sequence current protection is mainly directed at various ungrounded asymmetric fault. For
instance, when motor certain phase is broken, the magnitude of negative-sequence component is different, due to
load rate before fault. When load rate is large than 0.7, the sound phase could produce over current. Therefore,
conversional protection would not effectively protect asymmetric fault. During motor normal operation, due to
asymmetric power supply, some negative-sequence current would always exist, and this current would not exceed
30%Ie. Negative-sequence protection setting could avoid this negative-sequence current, and it is set to be 0.3Ie.
This protection would apply three-phase protection TA as tacitly applied. When using two-phase protection
TA, the control character should be KG1.11=1, and at this time, the negative-current could be computed according
to following formula:
The negative-sequence current in overheat protection would be computed according to above formula.
