5.1.7
Technical description
5.1.7.1
Starters
Starting procedure
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The REB500sys distance function is equipped with either over-current or underimpedance
starters. The setting of the parameter
StartMode determines which of the two is active.
A starter must pick up at least twice before its signal is processed (for phase selection,
starting timers, signaling etc.). Should a starter pick up only sporadically, only the backwards
measuring system and ancillary functions such as displaying measurements etc. are enabled.
Starting signals do not reset unless all the starters have reset.
Overcurrent starters (Istart)
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The variables at the inputs of the overcurrent starters are the phase currents I
L1
, I
L2
and I
L3
and
the residual current I
E
(3I
0
), respectively the neutral voltage U
E
(3U
0
). Firstly, a logic determines
I
max
, that is, the highest of the three-phase currents I
L1
, I
L2
and I
L3
.
If the value of I
max
exceeds the setting of the parameter
IStart (overcurrent starters), each of
the phase currents I
ph
is checked to determine whether it exceeds the setting of the parameter
Imin (current enable) and also 80% of I
max
.
In the case of the ground current I
E
, it is checked whether it exceeds the setting of the
parameter
3I0min and also 25% of I
max
. Depending on the setting of the parameter
And Fault
Mode (I
0
, I
0
AND U
0
, I
0
OR U
0
), it is checked at the same time whether the residual voltage U
E
has exceeded the setting of the parameter
3U0min (neutral voltage enable).
The logical signals L1, L2, L3 and E are accordingly set to logical 0 or logical 1. The kind of fault
and the phases involved are thus determined. This information is needed for
•
phase selection (determination of the loop to be measured)
•
signaling the kind of fault (signaling relays, LEDs etc.)
•
enabling signals for tripping and for starting the timers for the measuring zones
The starting signals reset if after measurement, the impedances of all six loops lie outside the
final impedance zone (if only the overcurrent starters are in operation, there is no
underimpedance starting characteristic and relay response is determined by the setting of the
overcurrent starter
IStart).
Section 5
1MRK 505 406-UEN B
Bay protection functions
52
Bay protection functions REB500
Technical manual
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