Troubleshooting confusion: What is the real problem?

[theripley]

At the least, surge arrestor(s) need to be installed (on PLC power supplies and other sensitive electronic devices) to help divert any currents during the power loss.

I would like to suggest placing a snubber diode & interposing relay to each of the output. If there will be any power problem in the future, this will protect all the PLC outputs. This may not really solve the exact power problem but it will, however, protect the PLC.

Would that be an overkill? Since the load of the PLC output is only a LED / CFL.

 

[leitmotif]

Ripley

I think if you do a bit of reading you will find
1. Diodes across a coil work very well in DC. They do not work well on AC
2. Use MOV for AC.

I assume the LEDs that replaced the CFL are also AC

Dan Bentler

 

[theripley]

Ripley

I think if you do a bit of reading you will find
1. Diodes across a coil work very well in DC. They do not work well on AC
2. Use MOV for AC.

I assume the LEDs that replaced the CFL are also AC

Dan Bentler

Thanks for the correction.

I have never used an MOV, is it expensive? Do you connect it on 1 line only?

 

[leitmotif]

Ripley

Thanks for the correction.

I have never used an MOV,
REPLY Well you gotta start sometime

is it expensive?
For just a 7W load I would guess USA $$ at 0.5 to maybe 1.00. More than likely high estimate.
Do you connect it on 1 line only?
REPLY to both sides of line either at load end or supply end. I like the supply end because that is what I am protecting.

SHORT story - got sent admin bldg because "lites are not working"
Start doing voltage checks and finding no problems. Another guy comrs by checks a socket OK. ALL of the bulbs were burned out.

SO
question -- in four years have the outputs failed and no one noticed??

At 7 Watt per CFL I have hard time believing this by itself is cause of relay failure. Has someone in past put in 100 W incandescant when CFL died?

Dan Bentler