Calculations B
Shield Fire, Safety and Security Ltd.
Shield A-XT Releasing Fire Control Panel - Installation and Operation Manual SEXTCP-OM
Revision E01.00
79 of 127
Current loading calculations do not include the combined IDC currents of the Shield A-XT Releasing
Fire Control Panel. These combined IDC currents are negligible in comparison to fire control panel, ancillary device
and NAC currents of the Shield A-XT Releasing Fire Control Panel and are therefore excluded from the current
loading calculation.
Current-Loading
Current-loading of the Shield A-XT Releasing Fire Control Panel is limited to the 2.0 Amp capacity of the power
supply and the 7 AH capacity of the standby-batteries. The standby-batteries can provide an operating duration of
twenty-four hours followed by five minutes of alarm when the standby current does not exceed 236 mA.
Standby and alarm current can include all or part of the following loads but cannot exceed the total maximum
currents specified:
NAC outputs on the Shield A-XT Releasing Fire Control Panel are load dependant and are limited to a maximum
current load of 500 mA. The releasing output on the Shield A-XT Releasing Fire Control Panel is load dependant
and is limited to a maximum current load of 1000 mA.
Current limits are provided in Appendix A, “Specifications” for each of the circuit of the A-XT Releasing Fire
Control Panel. Installers must identify the current-draw of each device and then compare the sum of these device
currents with the current limit provided for each circuit-output. The total device-current must be below the limits
provided for each circuit output specified in Appendix A, “Specifications”.
The calculation of total-current-loading during an alarm condition includes the sum of device-loads on each power
output circuit of the Shield A-XT Releasing Fire Control Panel. Power circuits of the fire control panel are pro-
vided on the terminals of NAC 1, NAC 2, and NAC 3, AUX 24V, STATUS UNITS and EXTING.
Loads Standby Current Alarm Current
FACP 100 mA 620 mA
Status Unit 50 mA (per unit) 83 mA average per unit (max)
94 mA peak per unit (max)
Ancillary Board 16 mA (per board) 175 mA per board (max)
NAC Outputs 0 mA (per NAC output) 500 mA (per NAC output)
Releasing Output 0 mA 1000 mA
Total Maximum Current 236 mA 2000 mA
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