Manual 37138C
ESDR 4T - Current Differential Protection Relay
© Woodward
Page 27/46
Configuring the Relay
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NOTE
•
Operating current (N.O.): The relay is enabled (i.e. in the operating state) when current flows through
the coil. If a loss of the supply voltage occurs, a change of state will not occur in the relay and no
triggering of fault conditions occur. In this mode of operation the condition of the system should be
monitored through other means than the state of the relay.
•
Idle current (N.C.): The relay is disabled (i.e. in idle state) when current flows through the coil. The re-
lay is energized in idle state. If a loss of the supply voltage occurs, a change of state will occur in the
relay and a triggering of fault conditions will occur.
Relay programmed as 'operating current relay'
Operating current
contact
Idle-current
contact
cu
rr
en
t flo
w
0 V
RELEASE
Relay operates
24 V
RELEASE
Operating current
contact
Idle-current
contact
RELEASE
Relay releases
no c
ur
re
nt
fl
ow
0 V
Relay programmed as 'idle-current relay'
RELEASE
24 V
Figure 6-2: Operating/idle current
Change relay-
function? YES
Change relay function?
YES/NO
YES
.............. The subsequent screens for the selection between operating current
and idle current contact are displayed.
NO
................ The subsequent screens are not displayed.
Funct. rel. 12
(R=releases) AA
Funct. rel. 34
(R=releases) RA
Relays 1, 2, 3 and 4 functions
A/R
A choice is made between different control principles with the selection of either
operating current contact (N.O.) or idle current contact (N.C.). An operating cur-
rent output can be used if an open circuit cannot lead to more serious faults; idle
current output performs advanced tasks, e.g. for lines relevant to safety. Relay 3
(readiness for operation) can only be operated as an idle current contact.
A
................... Operating current output (N.O.): the digital alarm output functions as
an operating current output.
R
................... Idle current output (N.C.): the digital alarm output functions as idle
current output.
Note:............. The alarm outputs for differential protection are changeover contacts.
Auto-acknowledge
relay ON
Self-acknowledging relay
ON/OFF
(Description for operating current output)
ON
................ The relay is automatically enabled (after the configured delay time
has expired), once the fault condition is no longer detected. Depend-
ing on how the parameter "
Self-acknowledging messages
"
is configured, will dictate how the control displays the error mes-
sages.
OFF
.............. The relays remain disabled and the messages are shown in the dis-
play until they have been acknowledged manually. The subsequent
screens of this parameter will not be displayed.
NOTE
.......... Subsequent setting is blocked:
•
"
Self-acknowledging relay
"
"
OFF
"
•
"
Self-acknowledgement of messages
" "
ON
"
