CAN A FAULTY MODUTROL MOTOR DAMAGE AN ANALOG O/P MODULE - SM 332

Dear All

We are using Honeywell make Modutrol Motor (Model- M7284C1000) in our Burner system. The Modutrol Motor is acting as a damper actuator, it has been controlled by 4-20 mA which is outputted by Analog O/P Module( Model - SM 332). We are using CPU S7- 300.

We are recently facing problem in this system for few of our customers.

Problem: We are observing that whenever these Modutrol Motors become faulty like the modutrol motor stopped working on getting the mA supply from the Analog O/P Module, after a few days of time the Analog O/P Module started showing 'SF' error LED ON and then we did not get the mA output from the Module from any of the 8 channels.

We have observed that:

I. For faulty Motor, the resistance between ‘+’ and ‘ – ‘ in the Terminal board of Motor is somewhere between~ 5.1KOhm to ~ 56 KOhm.

II. For OK motor, the resistance between ‘+’ and ‘ – ‘ is somewhere between ~101Ohm and 120 Ohm.

My question is:In the present connection system of Analog O/P Module and Modutrol Motor, if Modutrol motor is faulty, can it also make Analog O/P module faulty? - which is happening for few of our customers.

We have thoroughly checked all the connecting cables- found OK.

Thanks and Regards

Rajib L Das.