Siemens CU240B-2 - Page 101

Installing
4.6 Installing Control Unit
Converter with the CU240B-2 and CU240E-2 Control Units
Operating Instructions, 01/2016, FW V4.7 SP6, A5E34259001B AC
101
Additional options for wiring the digital inputs
Connecting P-switching contacts with an external
power supply
If you wish to connect the potential of
an external power supply with the p
o-
tential of the internal inverter po
wer
supply, then you must connect "GND"
with terminals 34and 69.
Connecting M-switching contacts with an external
power supply
Connect terminals 69 and 34 with one
another.
NOTICE
Damage to the CU240E-2 PN and CU240E-2 PN-F Control Units in the event of a short-
circuit of the 24 V output
It is possible that the Control Units are defective if the following conditions occur
simultaneously:
1. A short-circuit at the 24 V output occurs at terminal 9 when the inverter is operational.
2. The ambient temperature is at the upper permitted limit.
3. You have connected an external 24 V supply to terminals 31 and 32, and the voltage at
terminal 31 is at the upper permitted limit.
In order to rule out damage to the Control Units, you have to prevent all three conditions
occurring simultaneously.