ABB SPAC 531 C User Manual And Technical Description page 8

Protection functions
Phase overcurrent
protection
Directional neutral
overcurrent protection
I/O module
SPTR 6B11 of
protection modules
8
The overcurrent protection of the protection
module SPCJ 3C3 includes two operating stages,
a low-set stage and a high-set stage. The low-set
stage may be given a definite time or an inverse
definite minimum time (IDMT) characteristic,
whereas the high-set stage can operate with a
definite time characteristic only.
The two-stage directional earth-fault protection
module SPCS 3C4 measures the neutral current
of the object to be protected and the residual
voltage of the network. The earth-fault relay
module starts when the residual voltage exceeds
the set starting value and the measured current
and phase angle are such that the set starting
value of Iϕ> is exceeded. When the operation
time has elapsed the low-set stage of the earth-
fault relay module delivers a tripping signal. The
high-set stage operates in the same way; it starts
The I/O module SPTR 6B11 of feeder terminal
is located behind the system panel. The module
can be withdrawn after removal of the system
panel. The I/O module includes three optically
separated binary inputs (BS1, BS2, BACTRL),
five output contacts controlled by the protec-
+ +
BACTRL
BS1
BS2
IRF
SS1/U1
SS2/U1
SS1/U2
ARDUE
TS1/U2
TS2/U2
TS1/U1
TS2/U1
ENA
Fig. 4. Block diagram for I/O module SPTR 6B11.
+
F E
SGR/1
40
1
ms
SGR/8
SGR/2
40
1
1
ms
SGR/7
SGR/3
The module measures the phase currents of the
feeder to be protected. When a phase current
exceeds the setting value of the low-set overcur-
rent stage I>, the overcurrent stage starts, simul-
taneously starting its timing circuit. When the
set operating time has elapsed, a tripping com-
mand is delivered. In the same way the high-set
overcurrent stage starts when its setting value is
exceeded. It starts its timing circuit and per-
forms a tripping when the circuit has timed out.
when the residual voltage exceeds the set starting
value and the neutral current and the phase
angle between current and voltage are such that
the set starting value Iϕ>> is exceeded. When
the selected operation time has elapsed the high-
set stage delivers a tripping signal.
The high-set stage of the directional earth-fault
protection can be selected to operate in the same
direction as the low-set stage or, alternatively,
the opposite direction can be selected.
tion relay modules (output relays A, B, C, D, E)
and an IRF output contact (output relay F) that
is common to the protection relay modules and
the control module and indicates internal feeder
terminal fault.
D C
1 1
1
1
1
B A
SPTR 6B11