STATUS SCIENTIFIC CONTROLS MCU3 - Calculating the Backup Time for Your System

STATUS SCIENTIFIC CONTROLS
MCU System Installation and Hardware Configuration Manual
TD06/001
Issue:
6
Change Note:
1696
Page 1-13
Example 3 (Best Case)
A 4 channel system comprising of 4 toxic channels. All system relays are configured as normally
de-energised. No analogue outputs are being provided by the system.
Module and Detector Heads
Qty
Current
Controller & Display
1
x
36
=
36
mA
Input Module & Toxic Head
4
x
8
=
32
mA
Input Module & Oxygen Head
0
x
17
=
0
mA
Input Module & Flammable Head
0
x
41
=
0
mA
Common Relays (Energised)
0
x
17
=
0
mA
Input Module Relays (Energised)
0
x
17
=
0
mA
Input Module Analogue Output
0
x
4
=
0
mA
Total Current Required under normal conditions =
68
mA
Batteries are 1.2Ahr, therefore backup time is 1200/68 = 17.6 Hrs = 17 Hours 36 mins
1.6.2 Calculating the backup time for your system
Notes for Calculation
1. The Controller Module is always present on a functioning system and therefore its quiescent
current must always be included in any calculations.
2. If an external load is placed upon the system then the current that the load requires must be
added to the table prior to performing the final calculation.
Consider the system being installed, the detector heads being used and the normal status of all
relays within the system. Enter the quantities in the table below to assist in battery life
calculations.
Module and Detector Heads
Qty
Current
Controller & Display
1
x
36
=
36
mA
Input Module & Toxic Head
x
8
=
mA
Input Module & Oxygen Head
x
17
=
mA
Input Module & Flammable Head
x
41
=
mA
Common Relays (Energised)
x
17
=
mA
Input Module Relays (Energised)
x
17
=
mA
Input Module Analogue Output
x
4
=
mA
External Loads (e.g. Status Lamp)
x
=
mA
Total Current Required under normal conditions =
mA
The battery life can now be calculated by dividing 1200 by the total current required by the
system under normal conditions.