Battery and Power Supply Calculations
February 2012 A-6 P/N 06-237058-001
A-5 CALCULATING MAXIMUM LOAD FOR MULTIPLE POWER SUPPLY UNITS IN ONE ENCLOSURE
At a nominal operating temperature range of 32 to 120
°F (0 to 49 °C), the installer needs to be aware
of power supply limitations which occur when three or more PSU’s are present in a 3-Tiered or
2-Tiered Enclosure. After system installation, the maximum Alarm current load for the entire system
should be tested to verify that the power supplies are de-rated according to Tables A-5 through A-8:
* NOTE: Maximum current load cannot exceed 4 Amps for an individual PSU.
Table A-5. Power Supply Limitations for 3-Tiered Enclosure
Number of Power Supply Units
Inside Enclosure
Maximum Alarm Current for Enclosure
1 to 2 5.4 Amps per PSU
3 to 4 4 Amps per PSU
5 to 6 Not to exceed 20 Amps for entire enclosure*
Table A-6. Power Supply Limitations for 3-Tiered Enclosure with Dead Front Cover
Number of Power Supply Units
Inside Enclosure
Maximum Alarm Current for Enclosure
1 to 2 5.4 Amps per PSU
3 to 4 4 Amps per PSU
5 to 6 Not to exceed 17 Amps for entire enclosure*
Table A-7. Power Supply Limitations for 2-Tiered Enclosure
Number of Power Supply Units
Inside Enclosure
Maximum Alarm Current for Enclosure
1 to 2 5.4 Amps per PSU
3 to 4 Not to exceed 15 Amps for entire enclosure*
Table A-8. Power Supply Limitations for 2-Tiered Enclosure with Dead Front Cover
Number of Power Supply Units
Inside Enclosure
Maximum Alarm Current for Enclosure
1 to 2 5.4 Amps per PSU
3 to 4 Not to exceed 11 Amps for entire enclosure*
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