Hi guys, I am working at

[redlinej]

Hi guys,
I am working at power plant and we are using modicon quantum tsx plc to control and monitor the generators,i notice if we shut the generator down for maintenance and then try starting it after we have problems like sensor not reading, start signal not going trough,so the plant technician normally just turn the power off for a few seconds and then everything work fine ,can anyone explain this to me thanks.

 

[IRstuff]

And you don't think that the massive surges and whatnot that accompany a generator shutdown and restart might have a deleterious effect on an itty bitty PLC? Not to mention getting out of sync with the generator?

TTFN
faq731-376

 

[redlinej]

I think you misunderstand what i am saying they don't turn the power off to the plc while the generator is running, they turn the power off before starting and try to reset the plc.
P.S we can't shut down generator so we are controlling the grid.

 

[controlsdude]

I would look into what the PLC is doing during first scan. I know some processors require some initilization procedure at first scan. Maybe when you go to estop or some standby function on the processor that this initilization on the cards is wiped out or corrupted. Another possible cause, your probably shutting down remote racks and such and the network cant reset based on this happening, since a lot of power plant archetecture is distributed IO systems tied to the PLC.

 

[IRstuff]

Is the sequence of events ALWAYS the same? What about the timing?

There are only about 3 possibilities:
> the PLC is messing with you and just wants more attention
> the PLC has intermittent boot problems and repeatedly resetting it will eventually get it into the correct startup mode
> the PLC is dependent on something else that takes longer to boot.

TTFN
faq731-376

 

[BenTheLogic]

In a PLC. It's got retentive memory if you turn Plc power off for a few seconds, then you might be able to reset the value of those things. Another reason I think is possible is that the plc diagram is faulty... Just a guess.