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1260-22 User Manual
Module Power
Calculation
Module Operation 3-12
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The maximum power dissipation of the module needs to be
considered for each application. The module power can be
divided into three power components. They are the logic
circuitry, the relays and the channel paths.
Logic Power
The first component, logic power is one of two fixed values
depending on whether or not an Option –01T is installed. For a
1260-22 with an Option-01T installed the logic power is 8 Watts,
and if no Option –01T is installed the logic power is 3 Watts.
Relay Power
The second component, relay power, depends on the number of
relays that are energized and their duty cycle. A typical relay coil
dissipates about 0.8 Watts. So in order to calculate the total
power add the average power from each relay energized. The
average power for each relay is 0.8 Watts times the duty cycle,
t
/( t
+ t
). If t
is much greater than 1 minute assume a Duty
on
on
off
on
Cycle of 100%.
Channel Power
The third component is the channel power dissipation, which is
2
calculated from the I
R losses in each of the relay paths and the
duty cycle for each path. A typical path resistance is
approximately 0.020 Ohms. Therefore, the total power in the
paths is the sum of the average power in each path. The
average power is 0.02 times the path current squared, times the
duty cycle, t
/( t
+ t
on
on
assume a Duty Cycle of 100%.
To summarize the total Module Power refer to the following
equation:
P
= P
+ (P
+ P
TOTAL
LOGIC
K1
+ .... P
)
CH39
Where:
P
=
LOGIC
P
=
Kn
P
=
CHm
And I = the channel current in Amps,
D = t
/( t
on
D = 100% if t
EADS North America Test and Services
Publication No. 980673-055 Rev. A
). If t
is much greater than 1 minute
off
on
+ P
+ .... P
) + (P
K2
K3
K40
8 Watts (With Option-01) or
3.0 Watts (Without Option-01)
0.8 Watts x D
2
I
x 0.02 Ohms x D
+ t
).
on
off
>> 1 minute
on
+ P
+ P
CH0
CH1
CH2
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