24
TB MRD1-T 10.01 E
5.1.6
OFFLINE-TEST mode
For testing a parameter set the OFFLINE TEST mode
can be activated. In this mode all output relays are
being switched off. Now it can be changed over to
another parameter set for testing without risking nui-
sance tripping. If the parameter set causes tripping,
alarms are only shown on the MRD1 display or indi-
cated via LEDs. The OFFLINE TEST mode is enabled
or disabled on the SYSTEM SETTING page.
The OFFLINE TEST mode is indicated by:
•
Self-supervision relay de-energizes
(to inform the control system about the missing
protection function)
•
Self-supervision LED flashes red (= no protection)
•
LED TEST flashes red (= TEST mode active)
!
Important Notes
Important Notes
Important Notes
Important Notes
To prevent an unintended trip the OFFLINE TEST
mode is activated as default setting on first commis-
sioning. When the
MRD1
recognizes a damaged
parameter memory the default settings are loaded
automatically and the Offline mode is activated (with
selftest relay unenergized).
During OFFLINE TEST mode the transformer is not
protected by the
MRD1
. Although a failure could be
detected during this mode, the
MRD1
would not ini-
tiate a trip of the transformer.
In order to prevent dangerous conditions, the trans-
former must either have a sufficient backup protection
or has to be switched off.
After an intended OFFLINE TEST this mode must be
disabled so that protection is ensured again.
5.1.7
Reset (DEVICE RESET)
System messages in the display can be cancelled
with a short press on the RESET key. The message is
not removed at all but stored in the EVENT-memory.
A trip will also cause a message which is also to be
cancelled with a short RESET press. After this all
measured and calculated values can be recalled
from the fault recorder. All output relays and LEDs (if
set to self-holding contact) will remain in energized
position until a DEVICE RESET is initiated to the
MRD1
by a long RESET press from home position.
The DEVICE RESET can also be initiated by the ex-
ternal reset input or via serial interface.
Info-messages do not need to be reset manually.
They extinguish automatically after 5 s.
Summary of Contents for MRD1-T
Page 1: ...MRD1 T Transformer Differential Protection System ...
Page 26: ...26 TB MRD1 T 10 01 E ...
Page 40: ...40 TB MRD1 T 10 01 E Scheme ...
Page 64: ...64 TB MRD1 T 10 01 E ...