Calculating The System Current Draw; 1: Overview; 2: How To Use Table 7.3 On Page 165 To Calculate System Current Draw - Honeywell Fire-Lite Alarms MS-9200UDLSE Manual

Power Supply Calculations

7.3 Calculating the System Current Draw

To convert...
Milliamperes (mA) to
amperes (A)
Microamperes (
amperes (A)
164
7.3.1 Overview
The control panel must be able to power all internal and external devices continuously
during the non-fire alarm condition. To calculate the non-fire alarm load on the system
power supply when primary power is applied, use Calculation Column 1 in Table 7.3 on
page 165. The control panel must support a larger load current during a fire alarm con-
dition. To calculate the fire alarm load on the power supply, use Calculation Column 2
in Table 7.3 on page 165. The secondary power source (batteries) must be able to
power the system during a primary power loss. To calculate the non-fire alarm load on
the secondary power source, use Calculation Column 3 in Table 7.3 on page 165.
When calculating current draw and the battery size, note the following:
• 'Primary' refers to the main power source for the control panel
• 'Secondary' refers to the control panel's backup batteries
• All currents are given in amperes (A). Table 7.2 shows how to convert milliam-
peres and microamperes to full amperes.
Table 7.2 Converting to Full Amperes
µ
A) to
µ
7.3.2 How to Use Table 7.3 on page 165 to Calculate System
Current Draw
Use Table 7.3 on page 165 to calculate current draws as follows:
1. Enter the quantity of devices in all three columns
2. Enter the current draw where required. Refer to the Device Compatibility
Document for compatible devices and 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 7.4 on page 166
Following are the types of current that can be entered into Table 7.3 on page 165:
Calculation Column 1 - The primary supply current load that the control
panel must support during a non-fire alarm condition, with AC power applied.
Calculation Column 2 - The primary supply current load that the control
panel must support during a fire alarm condition, with AC power applied.
Calculation Column 3 - The standby current drawn from the batteries in a
non-fire alarm condition during a loss of AC power.
Calculating the System Current Draw
Multiply
mA x 0.001 3 mA x 0.001 = 0.003A
A x 0.000001 300
Example
µ
A x 0.000001 = 0.0003 A
MS-9200UDLS PN 52750:A 11/04/05