DC Current Draw Calculations
Power Supply Calculations
ACPS-2406 PN 51304:B 09/02/2003
31
Section 5 Power Supply Calculations
Calculations must be done to determine standby and alarm DC current loads. Ampere hour
requirements must be calculated as well to determine battery size.
In the following section, the term “secondary” refers to the ACPS-2406’s backup batteries: the
term “primary” is reserved for the ACPS-2406’s primary source of power, 120 VAC 50/60 Hz
power. The term “standby” refers to the output current required when no fire alarm is present. The
term “alarm” refers to the output current required when a fire alarm is present.
5.1 DC Current Draw Calculations
The ACPS-2406 provides filtered 24VDC power that may be used for operating Notification
Appliance Circuits or other external devices. The power for operating external devices is limited.
Use Table 5.1 through Table 5.5 to determine if external loading is within the capabilities of the
power supply.
1.
Enter the current draw values for each output into Table 5.1 through Table 5.4. If the Auxiliary
Power Supply (J1) is used, its current draw must be added to the current draw for Output 4 in Table
5.4. Refer to the Device Compatibility document and the device manufacturer’s data sheets
packaged with each device to find the standby and alarm current draws to use in these tables.
2.
Enter the Standby Current Total and the Alarm Current Total from each of these four tables
into Table 5.5, and add the figures in Column A and Column B to determine total DC current
draw.
Note: Columns A and B of Table 5.1 through Table 5.5 are not battery calculations. They are current
calculations to confirm whether the ACPS-2406 can output enough DC current to support its devices during
standby and alarm conditions.
Table 5.1 DC Current Draw Calculations, ACPS-2406 Output 1
OUTPUT 1
C
ATEGORY
COLUMN A
S
TANDBY
C
URRENT
(
AMPS
)
COLUMN B
A
LARM
C
URRENT
(
AMPS
)
Q
TY
X
CURRENT
DRAW
=
T
OTAL
Q
TY
X
CURRENT
DRAW
=
T
OTAL
Power Supervision Relays (A77-716B)
X =
A
X =
A
4-Wire Smoke Detectors
X =
A
X =
A
4-Wire Smoke Detectors
X =
A
X =
A
Annunciators
X =
A
X =
A
Auxiliary Devices
X =
A
X =
A
Auxiliary Devices
X =
A
X =
A
Auxiliary Devices
X =
A
X =
A
Notification Appliances
N
OT
A
PPLICABLE
X =
A
Notification Appliances
X =
A
Notification Appliances
X =
A
S
UM
EACH
COLUMN
FOR
TOTALS
O
UTPUT
1
S
TANDBY
C
URRENT
D
RAW
TOTAL
:
A
O
UTPUT
1
ALARM
C
URRENT
D
RAW
TOTAL
:
A
Note: S
TANDBY
C
URRENT
T
OTAL
for all outputs together cannot exceed 1.0 A.
A
LARM
C
URRENT
T
OTAL
cannot exceed 2.50 A for any single output.
