ABB RELION REX640 Technical Manual page 630
Protection and control
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Also See for RELION REX640:
- Technical manual (1760 pages) ,
- Operation manual (164 pages) ,
- Engineering manual (156 pages)
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Protection functions
In case tripping of cross-country fault is enabled (setting
"on"), then operation of IFPTOC requires that simultaneously both the magnitude
of calculated residual current (I
setting
Operate time for cross-country fault operation is given with setting
time . Typical operate time is 60-100 ms.
When start and operate conditions of cross-country earth fault module are fulfilled,
this is indicated by activation of START and OPERATE outputs and ST_XC and OP_XC
outputs.
In case tripping of cross-country fault is enabled, operate time is given with setting
XC stage Op time . Reset time is defined with setting Reset delay time . Note that
setting
definite time operation, but it must be taken into account in setting
time .
Applicable settings for cross-country earth fault module are:
stage A Str Val, XC stage PP V Val, XC stage Op time and Reset delay time .
Intermittent earth-fault protection
Operation time requirement of earth-fault protection in safety standards assumes
continuous flow of fault current. In case of resonant earthed network, earth faults
are often re-striking i.e. fault arc is not continuous, but intermittent. During re-
striking/intermittent earth faults, the very high but narrow current transient may
result to very fast operation times, if operation time is based on IDMT-operation i.e.
Operation curve type = Inverse time EN50522 or Inverse time IEEE80. Requirement
for operation with IDMT-timer is that timer is not reset between successive
current transients i.e.
case operation during re-striking/intermittent earth faults is preferably based on
number of counted transients, then setting
value, say 20-40 ms, and dedicated intermittent earth-fault protection functionality
must be enabled.
Intermittent earth-fault module is enabled with setting
Module is enabled by default. In case multiple instances of IFPTOC are applied in
the protection configuration, and operation during re-striking/intermittent earth
faults is preferably based on number of counted transients, only single instance
of IFPTOC requires Intermittent earth-fault module functionality to be enabled; in
other instances, Intermittent earth-fault module functionality may be disabled.
630
XC stage A Str Val during a detected earth fault:
The cross-country stage earth fault module always evaluates the true
fault current magnitude (considering the effect of setting
harmonics ) i.e. it is not affected by settings Ena RF Compensation and
Reduction factor .
The cross-country fault indication is given in Recorded data as
detection or in Output data as XC_FLT.
CB Delay comp (circuit breaker delay compensation) is not applicable in
Reset delay time should be set long enough. However, in
) and estimated earth-fault current (
o
Reset delay time should be set to low
1MRS759142 F
Enable XC Op mode =
) exceeds
(Equation 137)
XC stage Op
Enable
XC fault
XC stage Op
Enable XC Op mode, XC
Ena Intermit EF mode = "on".
REX640
Technical Manual
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