Pickup1: Operating level for the inverse characteristic, IEEE or tailor made
. The
operation is based on the relation between rated voltage and rated frequency and set as
a percentage factor. Normal setting is around 108-110% depending of the capability
curve for the transformer/generator.
Pickup2: Operating level for the t_MinTripDelay definite time delay used at high
overvoltages. The operation is based on the relation between rated voltage and rated
frequency and set as a percentage factor. Normal setting is around 110-180%
depending of the capability curve of the transformer/generator. Setting should be above
the knee-point when the characteristic starts to be straight on the high side.
XLeakage: The transformer leakage reactance on which the compensation of voltage
measurement with load current is based. The setting shall be the transformer leak
reactance in primary ohms. If no current compensation is used (mostly the case) the
setting is not used.
t_TripPulse: The length of the trip pulse. Normally the final trip pulse is decided by the
trip function block. A typical pulse length can be 50 ms.
CurveType: Selection of the curve type for the inverse delay. The IEEE curves or tailor
made curve can be selected depending of which one matches the capability curve best.
TDforIEEECurve: The time constant for the inverse characteristic. Select the one
giving the best match to the transformer capability.
t_CooolingK: The cooling time constant giving the reset time when voltages drops
below the set value. Shall be set above the cooling time constant of the transformer.
The default value is recommended to be used if the constant is not known.
t_MinTripDelay: The operating times at voltages higher than the set Pickup2. The
setting shall match capabilities on these high voltages. Typical setting can be 1-10
second.
t_MaxTripDelay: For overvoltages close to the set value times can be extremely long if
a high K time constant is used. A maximum time can then be set to cut the longest
times. Typical settings are 1800-3600 seconds (30-60 minutes)
AlarmPickup: Setting of the alarm level in percentage of the set trip level. The alarm
level is normally set at around 98% of the trip level.
tAlarm: Setting of the time to alarm is given from when the alarm level has been
reached. Typical setting is 5 seconds.
10.4.3.3 Service value report
M6496-144 v4
A number of internal parameters are available as service values for use at
commissioning and during service. Remaining time to trip (in seconds) TMTOTRIP,
Section 10 1MRK 504 163-UUS A
Voltage protection
630 Transformer protection RET670 2.2 ANSI
Application manual
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