Description Of Operation - ABB SPAJ 140 C User Manual And Technical Description

Description of
operation
The combined overcurrent and earth-fault relay
is a secondary relay to be connected to the
current transformers of the protected object.
The three-phase overcurrent unit and the earth-
fault unit continuously measure the phase cur-
rents and the neutral current of the protected
object. On detection of a fault the relay starts,
trips the circuit breaker, initiates auto-reclosing,
provides alarm, records fault data etc. in accord-
ance with the application and the configured
relay functions.
When the phase current exceeds the set start
current of the low-set stage I>, the overcurrent
unit starts delivering a start signal after a preset
~60 ms start time. When the set operate time at
definite time operation or the calculated operate
time at inverse time operation elapses, the over-
current unit operates. In the same way the high-
set stage I>> of the overcurrent unit starts deliv-
ering a start signal after a preset ~40 ms start
time, when the set start current is exceeded.
When the set operate time elapses, the overcur-
rent unit operates.
When the earth-fault current exceeds the set
start current of the low-set stage I
fault unit starts delivering a start signal after a
preset ~60 ms start time. When the set operate
time at definite time operation or the calculated
operate time at inverse time operation elapses,
the earth-fault unit operates. In the same way
the high-set stage I >> of the earth-fault unit
0
IL1
IL2
IL3
Io
BLOCKING
OR RESET
Fig. 1. Protection functions of the combined overcurrent and earth-fault relay type SPAJ 140 C.
starts delivering a start signal after a preset ~40
ms start time, when the set start current is
exceeded. When the set operate time elapses, the
earth-fault unit operates.
The low-set stage of the overcurrent unit and the
low-set stage of the earth-fault unit may be given
definite time or inverse definite minimum time
(IDMT) characteristic. When the IDMT char-
acteristic is chosen six time/current curves are
available. Four of the curves comply with the BS
142 and IEC 60255 and are named "Normal
inverse", "Very inverse", "Extremely inverse"
and "Long-time inverse". The two additional
inverse time curves called the "RI-curve" and
the "RXIDG-curve" are also provided.
By appropriate configuration of the output relay
matrix, the start signals of the overcurrent and
earth-fault units are obtained as contact func-
tions. The start signals can be used for blocking
co-operating protection relays, for signalling
and for initiating auto-reclosing.
The relay includes one external binary input,
which is controlled by an external control volt-
>, the earth- age. The function of the control input is deter-
0
mined by selector switches in the protection
relay module. The control input can be used for
blocking the operation of one or more protec-
tion stages, for resetting a latched output relay in
the manual reset mode or for enforcing a new set
of relay setting parameters by remote control.
THREE PHASE DEFINITE TIME
OR INVERSE TIME LOW-SET
OVERCURRENT PROTECTION
THREE PHASE INSTANTANEOUS
OR DEFINITE TIME HIGH-SET
OVERCURRENT PROTECTION
DEFINITE TIME OR INVERSE TIME
LOW-SET EARTH-FAULT
PROTECTION
INSTANTANEOUS OR DEFINITE
TIME HIGH-SET EARTH-FAULT
PROTECTION
REMOTE RESET, REMOTE SETTING
CONTROL OR BLOCKING INPUT FOR
THE DIFFERENT CURRENT STAGES
CIRCUIT BREAKER FAILURE
PROTECTION
SERIAL COMMUNICATION PORT
TRIP
51
SIGNAL 1
50
51 N
SIGNAL 2
50 N
START 1
START 2
IRF
51BF
SERIAL I/O
3