Siemens Simatic S7-400 - Manual (Page 414)

Cable Duct and Fan Subassemblies
9-2
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
9.1 Fan Monitoring in the Fan Subassemblies
In this section, you will find out how to monitor the fans.
There is a signaling concept example at the end of the section.
LEDs
The three red LEDs are assigned to the individual fans. From left to right, these
are:
F1 – for fan 1
F2 – for fan 2
F3 – for fan 3
Fans
The fans have a redundant design. The fan subassembly continues to function
even if one fan fails.
Fan Monitoring
The function of the fans is controlled by means of speed monitoring. If the speed of
a fan drops below the limit speed of 1750 rpm, the LED assigned to it lights up. In
addition, the relay K1 drops out.
If the speed of a second fan drops below the limit speed, the LED assigned to it
lights up; in addition, the relay K2 drops out.
The following table is the function table for the fan monitoring.
Table 9-1 Function of Fan Monitoring
Fan1 Fan2 Fan3 LED F1 LED F2 LED F3 Relay K1 Relay K2
– – – L L L – –
– – + L L D – –
– + – L D L – –
+ – – D L L – –
– + + L D D – +
+ – + D L D – +
+ + – D D L – +
+ + + D D D + +
–* –* –* D* D* D* –* –*
+ Fan in operation or relay picked up
– Fan failed or relay dropped out
D LEDs dark
L LEDs lit
* Power off