Siemens M7-400, S7-400 Example of Power Loss Calculation

M7-400 Expansions
12-20 S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Example of Power Loss Calculation
The following table contains a calculation example for the total power losses for an
AT adapter module with an AT module.
Table 12-6 Calculation Example for Total Power Losses of an ATM 478 with AT Module
Remark Voltage Current
Consumption Power Losses
+ 5 V 0.8 A 4 W
Power losses of the AT module
+ 12 V 0.1 A 1.2 W
Power losses of the AT module - 12 V 0.05 A 0.6 W
- 5 V – –
Power losses of the internal power supply
of the
ATM 478 for supplying the AT module
(P+12V + P-12V + P-5V) x 0.3
(1.2 + 0.6 + 0) x 0.3 W 0.54 W
Power losses of the ATM 478 AT adapter module 0.6 W
Total power losses of the ATM 478 adapter module with AT module 6.94 W
In this example, the power losses are 6.94 W. The ATM 478 AT adapter module
can be operated without forced ventilation.