Failure Alarms - Toshiba GRT100 Series Instruction Manual

Watchdog Timer
A hardware timer which is cleared periodically by software is provided and it is checked that the
software is running normally.
DC Supply monitoring
The secondary voltage level of the built-in DC/DC converter is monitored and checked that the
DC voltage is within a prescribed range.
3.3.3

Failure Alarms

When a failure is detected by the automatic supervision, it is followed with LCD display, LEDs
indication, external alarms and event recording. Table 3.3.1 summarizes the supervision items
and alarms.
The LCD messages are shown on the "Auto-supervision" screen which is displayed
automatically when a failure is detected or displayed by pressing the VIEW key. The event
record messages are shown on the "Event record" screen by opening the "Record" sub-menu.
Those alarms are retained until the failure is recovered.
Those alarms can be disabled collectively by setting the scheme switch [AMF] to OFF. The
setting is used to block unnecessary alarms during commissioning test or maintenance.
When the Watchdog Timer detects that the software fails to running normally, LCD display and
event recording on the failure cannot be expected.
DC supply failure disables the LCD display and event recording on the failure as well.
For the discrimination of the two failures mentioned above, refer to Section 6.7.2.
Supervision Item
AC input
imbalance monitoring
A/D accuracy check
Memory monitoring
Watchdog Timer
DC supply monitoring
(1): Diverse messages are provided as expressed with "---fail" in the Table in Section 6.7.2.
(2): The LED is on when the scheme switch [SVCNT] is set to "ALM" and off when set to
"ALM & BLK" (refer to Section 3.3.4).
(3): Whether the LED is lit or not depends on the degree of the voltage drops.
(4): The binary output relay "FAIL" operates.
3.3.4 Trip Blocking
When a failure is detected by the following supervision items, the trip function is blocked as long
as the failure exists and restored when the failure is removed.
 A/D accuracy check
 Memory monitoring
Table 3.3.1 Supervision Items and Alarms
LCD Message LED
"IN SERVICE"
(1) On/Off (2)
(1) Off
---- Off
---- Off
 59 
LED Ext. alarm
"ALARM"
On (4)
On (4)
On (4)
(3) (4)
6 F 2 S 0 7 8 9
Event record
Message
CT err
Relay fail
Relay fail
----
Relay fail