ABB RELION REX640, Техническое руководство, Страница: 601 / 1960

Figure 342: Permissible time-touch voltage characteristics given in standard EN
50522
• Time margin for practical circuit-breaker operate time can be applied with
setting
CB delay Comp. Default time margin is 0 ms.
•
START
and
ST_EF
outputs are activated when estimated effective earth-fault
current magnitude (considering the effect of settings
Reduction factor and
Enable harmonics) exceeds setting EF current Str Val and earth fault is detected,
and earth-fault current estimate is validated. Note that
Ena RF Compensation =
“Enable” does not affect this start condition.
•
OPERATE
and
OP_EF
outputs are activated according to the operate time - touch
voltage and earth potential rise requirements defined in standard EN 50522. i.e.
operate time is inversely proportional to the estimated fault current.
• Reset timer is started if any of the above conditions for
START
is not anymore
valid.
START
and
ST_EF
outputs stay activated until the reset timer expires
(setting
Reset delay time). After
OPERATE
output activation,
START
,
ST_EF
,
OPERATE
and
OP_EF
outputs are reset immediately i.e. reset delay time is no
longer valid. During re-striking/intermittent earth faults, the very high current
transient may result to very fast operation times. In case longer operation time
during re-striking/intermittent earth faults is preferred and operation should
be based preferably on counted number of transients, then setting
Reset delay
time should be set to low value, say 20-40 ms. Dedicated intermittent earth-fault
protection functionality based on counted number of transients is described in
Chapter 4.2.10.5.6 Intermittent earth-fault protection
.
• Applicable settings are:
Reduction factor, EF current Str Val, CB delay Comp, UTp
multiplier, Maximum earthing Ris, IDMT stage Min Op Tm, IDMT stage Max Op
Tm, Reset delay time.
It is important to note, that:
1MRS759142 F Protection functions
REX640
Technical Manual
601