EQUIPMENT:  T1200-C 
PUBLICATION:  MARINEC-P-A 
  ISSUE No. & DATE:   3  02/14 
© 2014 Thorn Security Ltd      PAGE 63 of 67 
Registered Company: Thorn Security Ltd.  Registered Office: Dunhams Lane  Letchworth Garden City  Hertfordshire  SG6 1BE 
22.3  Power Supply Load Calculation 
The power supply load must not exceed the maximum identified below: 
 
To determine the maximum power supply load perform the following steps: 
1.  Look-up the mains failed panel load in alarm. Enter this value as I
panel
. 
2.  Calculate the maximum load on the alarm circuits in mA in an alarm condition. Enter this value as I
alarms
. 
3.  Calculate the load on the auxiliary supply in mA in an alarm condition. Enter this value as I
aux
. 
4.  Calculate the maximum power supply load using the formula below: 
 
panel 
alarms 
aux 
 
pse
panel
aux
alarms
(..........+……….+……….)/1000    Amps 
 
Warning: 
The value of I
pse
 must not exceed the maximum permissible load for the panel (see table above). 
Overloading the power supply will result in automatic shutdown of the power supply during a fire alarm 
condition. 
22.4  Minimum Standby Battery Capacity Calculation 
This section describes how to calculate the minimum required standby battery capacity for the control panel. To 
determine the battery capacity, perform the following steps: 
1.  Look-up the mains failed fault battery current. Enter this value as I
panelfault
. 
2.  Look-up the mains failed alarm battery current. Enter this value as I
panelalarm
. 
3.  Calculate the maximum load on the alarm circuits in mA in an alarm condition. Enter this value as I
alarms
 
and enter this figure in the table. 
4.  Calculate the load on the auxiliary supply in mA in the quiescent condition. Enter this value as I
auxfault
. 
5.  Calculate the load on the auxiliary supply in mA in an alarm condition. Enter this value as I
auxalarm
. 
6.  Calculate the total battery load in fault, I
fault
. 
7.  Calculate the total battery load in alarm, I
alarm
. 
8.  Enter the required standby time in hours, T
fault
. 
9.  Enter the required time in alarm in hours, T
alarm
.