Hy,

I have implemented a controller for alternately driving two
motors 3 phase .5 Hp (grinders) after every hour one by one
. I have tested in the R&D and there was no problems with the
controller but now after its few days working in the actual
environment the controller 8051 software is working faulty
and is unable to drive the second grinder whenever the other
grinders turn comes after 1 hour it returns to the first and
never drives it . I wonder what is happening ??????

I have galvanic isolation between my microcontroller and the
grinder contactors . Please suggest me what could be the
reason of faulty working of the controller ? I have encapsulated
the controller in the aluminium casing but whats going wrong?


Thanks/
Ricky Chang