50
HPFF12 NAC Expander —
P/N 53576:B 11/24/2010
Power Supply Requirements
Calculating the System Current Draw
6.3.2 How to Calculate System Current Draw
Use Table 6.4 to calculate current draw as follows:
1. Enter the quantity of devices in all three columns.
2. Enter the current draw where required. Refer to the specifications of compatible devices for
their current draw.
3. Calculate the current draws for each in all columns.
4. Sum the total current for each column.
5. Copy the totals from Column 2 and Column 3 to Table 6.4.
Following are the types of current that can be entered into Table 6.4 on page 50.
•
Calculation Column 1
— The primary AC supply current load that the power supply must
support during a non-alarm condition, with AC power applied
•
Calculation Column 2
— The primary AC supply current load that the power supply must
support during an alarm condition, with AC power applied
•
Calculation Column 3
— The standby current drawn from the batteries in a non-alarm
condition during a loss of AC
Table 6.4 contains three columns for calculating current draws. For each column, calculate and
enter the total (in amperes) in the bottom row. When finished, copy the totals from Calculation
Column 2 and Calculation Column 3 to Table 6.5.
Device Type
Calculate Column 1
Primary, Non-Alarm Current
(Amps RMS)
Calculate Column 2
Primary, Fire Alarm Current
(DC Amps)
Calculate Column 3
Secondary, Non-Alarm Current
(DC Amps)
Qty X (current draw) = Total
Qty X (current draw) = Total
Qty Excrement draw) = Total
Main Circuit Board
=[0.207]
=[0.206]
= [0.075]
Trouble Contacts
(coil current)
1 X [0.0659] =
1 X [0.0659] =
= 0.0
[ ] X[ ] =
NAC Output #2
[ ] X[ ] =
NAC Output #3
[ ] X[ ] =
NAC Output #4
[ ] X[ ] =
Auxiliary Output
Current Draw from
TB4
Terminals
+A & –A
[ ] X[ ] =
[ ] [ ] =
[ ] X[ ] =
[ ] [ ] =
[ ] X[ ] =
[ ] [ ] =
Sum each column
for total:
Primary Non-Alarm =
Primary Alarm
Secondary Non-Alarm =
1.
Current limitation on TB4 NAC circuits is 3.0 Amps per NAC.
2.
Current limitation on TB4 AUX Output is 2.0 Amps.
3.
Total current draw cannot exceed 12.0 Amps in alarm.
Table 6.4 System Current Draw Calculations
