TWIDO TWDLCAE40DRF Problem

[malindesha]

I have Scneider PLC TWIDO TWDLCAE40DRF and it has unusual problem.

when after the PLC Off several minutes and turn it on, the plc not working, only show rapid speed blink on(PWR) LED. after 1-3 minutes it will power on and start the programme running.

this will only happen the plc leave off in several minutes and turn it on only, when it off and on in short time period it will power on quikly after on.

plc show BAT LED in red; is it low in PLC internal battery?

 

[Lancie1]

1. PLC internal battery is low;
2. The capacitiors inside the PLC may be failing;
3. The PLC power supply could be too small to supply power to all the devices connected to the PLC.

 

[malindesha]

thanks Lancie1 for reply!

i think this is plc power supply error because, i have tested the plc switching power supply voltage out to plc main board, it have 3 voltage output to plc main board,

24V stable
24v variable
5v stabe

i discover that 24v stable out not stable in this plc. when it turn on 24v stable out show low voltage and slowly increase some time increase to its original value 24v. but most of time it out 12-18 v maximum. but when i turnoff the power to power supply output slowly decrease and end of the capacitor discharging time (about 5s) out is suddenly increase to 24v and off. when this happen if i turn it on the power then out 24v continue sly and plc working fine also.

to resolve this i have changed all large value capacitor in the plc power supply unit but no good result, if there is fault in opto-coupler or what?

 

[Lancie1]

I do not know what it could be. Can you try disconnecting all devices that use 24V Stable, then checking the that 24V to see if becomes more stable?

If so, you might have a power-using device that is partially shorted to ground, or one that is using more power than it should, or simply too many devices drawing power from this supply.

 

[malindesha]

I have check the plc taken from panel plc itself only no input or output devices connection attached.