
adccommunitymod (AutomationDirect) asked a question.
Created Date: May 05,2014
Created By: dsto
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I am going to be using a D0-06DR PLC with relay outputs. They are going to power a 12VDC coil on some MAC air valves. Do i need to install transorbs to help protect the plc? I cannot find any specifically made for 12VDC power. I 've also thought about running fast blow fuses but I don't want to have to change them all the time. Is it really necessary to even run any of this? The plc outputs are rated up to 240VAC and 2 amps.. How likely is it that the coils may damage the plc? We have another D0-06DR that runs several coils both ac and dc. without any protection on either side for over 4 years without an issue yet. Thanks for any info you can get me!
Created Date: May 05,2014
Created by: Tinker
"Do i need to install transorbs to help protect the plc? " "We have another D0-06DR that runs several coils both ac and dc. without any protection on either side for over 4 years without an issue YET . "
From you experience it looks like you don't "need " to use them, but you really should.
With a transistor output it would be critical to use them, but even while a relay may stand the abuse for a while, the life will be considerably reduced.
Since you are protecting the PLC outputs, not the load, a 24 volt (easier to get) transorb would work fine with your 12V circuit, or even easier to get, just use a diode. The PLC manual should have snubber wiring information
Created Date: May 06,2014
Created by: dsto
I was also thinking that a 24v transorbs would work fine with what I am doing.
I know I could get away without using them for a while, but the coils will cycle 2-3000 times a day which will add up fast. I checked the inrush current today and it was around 800milliamps and the coils held at 500ma. I haven't had a chance to check and see what the voltage spikes to when the the coil goes from on to off position. Will try that in the morning. Im guessing the
ZL-TSD8-24 transorb module would be my quickest fix.?
Created Date: May 06,2014
Created by: AlbertL
This application note has a lot of good information and suggestions:
http://support.automationdirect.com/docs/an-misc-032.pdf
Created Date: May 05,2014
Created by: dsto
I am going to be using a D0-06DR PLC with relay outputs. They are going to power a 12VDC coil on some MAC air valves. Do i need to install transorbs to help protect the plc? I cannot find any specifically made for 12VDC power. I 've also thought about running fast blow fuses but I don't want to have to change them all the time. Is it really necessary to even run any of this? The plc outputs are rated up to 240VAC and 2 amps.. How likely is it that the coils may damage the plc? We have another D0-06DR that runs several coils both ac and dc. without any protection on either side for over 4 years without an issue yet. Thanks for any info you can get me!