Detcon 110A-FB-BBU - Manual (Page 3)

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1.6 ALARM CONTACTS
Contacts are provided for 3 alarms; High, Low and Fault and are rated 8 amp @ 117 VAC / 5 amp @ 30
VDC. Alarm contacts are Form C dry contacts; common, normally open and normally closed. A 5 amp
micro-fuse is provided in series with the common relay contact for each alarm.
A remote mounted normally open momentary switch may be used to reset the Model 110A-FB-BBU
controller. The reset function is effective when the alarms have been programmed in the latching position
and alarm conditions have passed.
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1.8 REMOTE RESET
The alarm reset switch located on the 110A-FB-BBU motherboard is a normally open momentary
switch. The reset function is effective when the Low and/or High alarms have been programmed in the
latching position and alarm conditions have passed.
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1.7 ALARM RESET
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1.9 ALARM DISABLE
An alarm disable switch located on the motherboard will deactivate the Low and High alarm relays. An
LED indicator located next to the switch will light when in the disable mode. CAUTION: The alarm disable
function is a completely manual operation and care must be used to remember to put the switch back in
the "Able" position after maintenance is completed.
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1.10 POWER REQUIREMENTS
Model 110A-FB-BBU contains an internally mounted 24 vdc power supply that operates on 117 vac.
Terminations are also provided on the motherboard for auxilary DC input (on model 110A-FB-BBU, these
terminals are used for the battery backup). A 1/2 amp 3AG slow blow fuse mounted on the power supply
protects against excessive line power (117 vac). To replace, remove the 110A-FB face plate and then the
controller board directly above the power supply. Excessive DC current is protected by a 1 amp micro-fuse
located on the mother board.
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1.11 FAULT CIRCUIT FUNCTIONS
Model 110A-FB-BBU digital controls feature fail safe supervisory circuits designed to assure maximum
reliability in system performance. The fault circuits supervise all field wiring between remote mounted
sensor assemblies as well as supervise critical internal power supplies. Field wiring between sensors and
control modules consists of + and – power loop and the 4-20 madc signal loop referenced to the – power
loop. The fault relay is normally energized and will de-energize in the event of open power or signal loop
between sensor and control module. Additionally the fault circuit will illuminate the front panel fault LED. The
power loop to the remote sensor is fused (1/2 amp) on the motherboard to prevent circuit damage as a
result of reverse polarity termination, induced transient spikes or shorted field wiring.
Detcon Model 110A-FB-BBU Gas Detection System PG.3
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1.12 DISPLAY ZERO
The potentiometer (see drawing #800.27A) labled "Display Zero" is used to calibrate the digital display
in accordance with the 4-20 madc signal input. This is factory set and should not require any user
adjustment. Should fine tuning become neccessary the display should be calibrated to read "01" with a
signal input of .16 madc.