View Full Version : How to solve STT fail Error on MYCOM CPIII , VLD200

25-06-2012, 04:57 PM
Dear Friends
Hi, We have a Mycom 200vld compressor and it was work well but , it just stop some times and show STT fail on CPII monitor.
i check the manual and it said that :
compressor running confirmation,a contact of the motor starter on digital input2 , is not detected by the CP-III/E when compressor start signal was given.

Does anybody know how to get ride of this alarm and solve it?


25-06-2012, 05:28 PM
Hi Jahangir.
A good place to start would be to check your Compressor Motor Start Feedback.
Which has a relay (MSRB) which is normally open circuit through terminals 12a and 12b on your Digital input / output board. this circuit makes on start-up.
It could be as simple as the relay has failed?
Worth a check anyway.

wiring diag. to follow.


Wiring diagram. may help?

25-06-2012, 05:39 PM
Hi Grizzly.
you mean than , when compressor is running the 12a and terminal COM should be close? if then might be another problem or something else?


I check the file . so thanks anyway