Choosing The Power Supply Module - Siemens 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.
Selection of the power supply for an M7-400 configuration is described separately
in Section 8.3 "Electrical Configuration." 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 414-1
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.
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04
Module Quantity
1
3
5
6
1
Wiring the S7-400
+5 VDC (Max. Current Consumption
Values)
I / Module
1800 mA
700 mA
30 mA
200 mA
140 mA
I Total
1800 mA
2100 mA
150 mA
1200 mA
140 mA
5390 mA
4-3