Choosing The Power Supply Module - Siemens SIMATIC S7-400 Installation Manual

4.2

Choosing the Power Supply Module

Estimating the Power Requirement
You should make an estimate of the power requirement for each rack of your
S7-400 system in order to select the appropriate power supply module for the rack.
Current consumption and power dissipation of the individual modules can be found
in the relevant data sheets.
Calculation Example
The following modules are to be fitted in a CR with 18 slots:
• 1 CPU 414-1
• 3 analog input modules SM 431;AI 16 x 16 bits
• 5 digital input modules SM 421;DI 32 x 24 VDC
• 6 digital input modules SM 422;DO 32 x 24 VDC/0.5A
• 1 send IM, IM 460-0
You can calculate Current Consumption I in this rack as follows, with the data from
the individual data sheets:
CPU 417-4
SM 431; AI 16 x 16 bits
SM 421;DI 32 x 24 VDC
SM 422;DO 32 x 24 VDC/0.5A
IM 460-0
Total
From the data in the table, you can see that you must install a power supply
module PS 407 10A (for connection to 120/230 VAC) or PS 405 10A (for
connection to 24 VDC) in the rack, to cover the current consumption calculated
here.
Note
If you wish to connect an ER to the CR via a send IM with current transfer, you
must also take the current consumption of this ER into account when choosing the
power supply module.
Automation System S7-400 Hardware and Installation
A5E00850741-01
Module Quantity
+5 VDC (Max. Current Consumption
I / Module
1 2600 mA
3 700 mA
5 30 mA
6 200 mA
1 140 mA
Wiring the S7-400
Values)
I Total
2600 mA
2100 mA
150 mA
1200 mA
140 mA
6190 mA
4-3