Fluke Biomedical 945A - Manual (Page 32)

Manual Reset
When an alarm trips, the relay coil goes to its abnormal position. The indicator flashes until the alarm is
acknowledged by pressing the ALARM ACK button on the UDR. The indicator then remains steady on
until the alarm condition becomes false. At that time, the alarm resets by turning the indicator off and
returning the contact to its normal position.
Auto Reset
When an alarm trips, the contact goes to its abnormal position. The indicator goes steady on. When the
alarm condition becomes false, the alarm automatically resets, returns the relay coil to normal position,
and turns the indicator off.
Auto reset may be selected for the HIGH and WARN alarms by removing jumper JP3-3 from the UDR
main board.
Standard relay operation for the UDR is fail-safe. When the unit is powered, the relay coil energizes. If
power is lost to the relay coil, or an alarm condition occurs, the relay de-energizes, giving a trip indication.
This logic provides fail-safe operation for the alarm function.
Non-fail safe relay operation for the HIGH and WARN alarms is available as an option.
HIGH Alarm
The HIGH alarm condition is "true" when the display dose rate is greater than or equal to the HIGH alarm
set point and "false" for all other conditions.
The standard logic for the HIGH alarm is fail-safe, manual reset.
When the HIGH alarm is tripped, the red HIGH alarm indicator begins flashing, the bargraph goes to red,
the HIGH alarm relay coil de-energizes, and the UDR commands the preamplifier to set its auxiliary
output high. When the alarm is acknowledged, the HIGH alarm indicator goes steady on and the UDR
commands the preamplifier to set its auxiliary output low. The auxiliary output on the preamplifier can be
used to drive a remote alarm/alarm indicator. The HIGH alarm relay will change state when the radiation
value drops below the setpoint if the alarm has been acknowledge.
The HIGH alarm is inhibited in Auto-Zero and Loop Test modes, and may be inhibited in Check Source
and Maintenance modes via jumper selection.
WARN Alarm
The WARN alarm condition is "true" when the display dose rate is greater than or equal to the WARN
alarm set point and "false" for all other conditions.
The standard logic for the WARN alarm is fail-safe, manual reset.
When the WARN alarm is tripped, the amber WARN alarm indicator begins flashing, the bargraph goes to
amber, the WARN alarm relay coil de-energizes. When the alarm is acknowledged, the WARN alarm
indicator goes steady on. With the alarm acknowledged, the relay will change state when the radiation
value drops below the setpoint.
The WARN alarm is inhibited in Auto-Zero and Loop Test modes, and may be inhibited in Check Source
and Maintenance modes via jumper selection.
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