any issue with multiple surge devices on solenoid coils?

i've been told numerous time not to stack surge suppressors, but have never been told the reason why...?!?

we have a project and there's solenoids on it (both AC and DC) that we will never see until we get out in the field to do install (proprietary info ****...), so that being said we have no details on solenoids other than the voltages. we want to put surge suppressors on them but are hesitant to do so bc the solenoids likely already have internal surge suppression built into them. hence the reason i'm looking for an answer as to why you can't have multiple sure suppressors

Why would you want more than one per solenoid?

Multiple surge suppressors will last longer, especially on AC.

Surge power strips usually have 1 MOV across Hot to Neutral, better ones have 3 MOV's (hot-Neutral, Hot-Ground, Neutral-Ground) and top of the line surge power strips have multiple MOV's Hot-Neutral. When a MOV absorbs a surge it gets a little damage internally, enough surges and it is completely dead.

For DC surge diodes, having 2 parallel would not be anything to worry about, but a bank of many could drop the reverse blockage down and cause problems.

Welcome to the forum.

proprietary info in regards to valves is silly. you are not asking for the entire design, just the solenoid valve info.

you need to go to your customer and explain that you need the valve name and model numbers so you can build your system.

if you fail to put in surge protection, the valves won't have it, which means you have to buy the terminals and rewire them. this will cause several days / weeks to do. the customer needs to know this and he will be charged any additional costs.
buying the surge terminals will cover you, but the valves will have surge protection on them.
this is a no win.
get with your manager and explain to him your delima, let them figure it out.
when the customer sees an additional cost for the project, he typically will give you what you want. that has been my experience.
james

dogleg43 said:

Why would you want more than one per solenoid?

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poorly written on my part... multiple surge protectors on each of the solenoids

Aabeck said:

Multiple surge suppressors will last longer, especially on AC.

Surge power strips usually have 1 MOV across Hot to Neutral, better ones have 3 MOV's (hot-Neutral, Hot-Ground, Neutral-Ground) and top of the line surge power strips have multiple MOV's Hot-Neutral. When a MOV absorbs a surge it gets a little damage internally, enough surges and it is completely dead.

For DC surge diodes, having 2 parallel would not be anything to worry about, but a bank of many could drop the reverse blockage down and cause problems.

Click to expand...

great info there, thanks!
we want to put one surge protector on it on our side, and there also may be one built into the valves themselves that we dont know about, so there would be a max of 2 surge devices per solenoid

so what happens if there's 2 MOV's that are both hot-neutral??? any issues there?

James Mcquade said:

Welcome to the forum.

proprietary info in regards to valves is silly. you are not asking for the entire design, just the solenoid valve info.

you need to go to your customer and explain that you need the valve name and model numbers so you can build your system.

if you fail to put in surge protection, the valves won't have it, which means you have to buy the terminals and rewire them. this will cause several days / weeks to do. the customer needs to know this and he will be charged any additional costs.
buying the surge terminals will cover you, but the valves will have surge protection on them.
this is a no win.
get with your manager and explain to him your delima, let them figure it out.
when the customer sees an additional cost for the project, he typically will give you what you want. that has been my experience.
james

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i agree, but we've tried (multiple times) and they are not going to give us any info... the valves are custom made for this project, but still...:angr:

we would buy the cablesets with the surge built into them so we'd be replacing the factory din connectors on the valve. but some of their valves (rexroth) have them built into the coil which is where the possibility of multiple surge suppressors comes from.
management is well aware. but on this large of a project (multi-million $$$) they're not even paying attention to the few thousand dollars I'll have in the solenoid cables, they just want it handled...

EMILLER233 said:

so what happens if there's 2 MOV's that are both hot-neutral??? any issues there?

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I have a home made surge suppressor I built for my main computer outlet, before I had a UPS - but I still have it.

It is a 120V plug that I have squeezed as many MOV's in as I physically could. it has 2 each from Neutral to Ground and about 4 from Hot to Ground, and at least 8 or 10 from Hot to Neutral.

If you had the room you could put as many MOV's as you can fit.

There are plenty of panels in use with surge suppressors across, or near, the PLC outputs and another at the relay or solenoid coils.

if your customer is refusing to budge,
have your contracts manager send the customer rep a certified letter, and an email expressing your concerns with regards to this issue.

state that if you buy the surge suppressors and the solenoids do not have protection, and the surge suppressors you buy fail, the customer will be responsible for purchasing new surge devices that will meet the requirements of the solenoids since your repeated efforts to obtain the information have failed.

a KEY ISSUE is what is the holding current of the solenoids? a 1/4" valve doesn't requirement, but a 2" valve is a whole different matter. a standard plc output will not power this valve. you need that also included in the documentation. re-reading your post makes me think that you are being set up for a big fall in regards to this point. if you need interface relays to power the valves, that's additional costs!

document everything and save ALL correspondence- even emails in case the project goes sideways and the legal department gets involved.
that saved my former company from a massive lawsuit from an auto company.
our customer supplied parts to an car company and requested we remove a critical test in the assembly process. he signed our change order paperwork and got my customer in massive hot water since the auto company did their own testing and all the parts failed.
james

EMILLER233 said:

i agree, but we've tried (multiple times) and they are not going to give us any info... the valves are custom made for this project, but still...

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What is the source of the concerned surge? External source or the solenoid? Have you measured the parameters for this threat? Number of pulses, voltage, time, fundamental frequency, or current?

I would suggest planning for worst case.

For AC coils use overrated MOV's. For DC coils use back to back Zener diodes to handle either polarity. And Zener diodes that are rated larger than normally spec'd.

As an independent contractor I would probably walk at this point. A customer like this doesn't know what they want and will be giving you Engineering Changes from the day the project is started until weeks after it is commissioned.

Aabeck said:

For AC coils use overrated MOV's. For DC coils use back to back Zener diodes to handle either polarity.

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MOVs are the old technology. Since then, avalanche diodes have been developed and are better suited to that function (both for AC and DC). An answer that could be better had numbers and other relevant details been provided (as requested).

I still say you need to get someone involved with the contact involved.
having surge terminal blocks there when you don't need them will cover you, BUT, not knowing the size of the valves can kill you. By that I mean that a 1/4" valve takes little current from a plc output. A 2" valve takes more current than a typical output can deliver and you will need an interface relay to deliver the power. those interface relays may need an additional panel and wiring you didn't plan on.

james

I’ve been following this thread and still don’t understand all of this concern about the need to add additional surge protection.

Do these valves interface with a PLC output module?
If so, are they relay dry contact modules, triac, or what? Some Allen-Bradley dry contact modules have surge/snubber protection built into them.

Or, are you worried about the surge coming from the incoming power? If so, do something to clean up the incoming power. I’ve controlled many high speed systems with valves and never had problems.

Just curious.

dogleg43 said:

I’ve been following this thread and still don’t understand all of this concern about the need to add additional surge protection

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EMILLER233 said:

i've been told numerous time not to stack surge suppressors, but have never been told the reason why...?!?

... (both AC and DC)... we have no details on solenoids other than the voltages.

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Dogleg, the OP was just asking if anything bad will happen if he uses 2 'surge suppression' devices instead of only 1. Particularly as multiple unnamed sources have said not to. The answers have included anecdotal evidence of >1 surge suppression devices, so perhaps it is answered?

I guess the main concern in the answers is the OPs statement about not knowing anything about a valve other than its voltage. Is it 24V AC or DC? Presumably one can obtain the "world's highest amp 24V solenoid" from the Guinness world records and design for that.