Your Opinion Please 1

[PUMPDESIGNER]

Please look at the photographs at this link I just set up.

http://www.fisstate.org/test51.htm

I am looking for insights, facts, and real knowledge about these products.

To be honest I do not like these devices. Many use them and claim "surge protection"!!!. But I do not see any value in these devices to protect controls. It seems to me that by the time a spark occurs, everything I value is already gone. Not only that, but it seems to me that if lightning has come through miles of air just to get to me, a little more sparking will not help.

But I am not an electrical engineer, so I look forward to your comments. We use many other devices that we know work well. But I would like to have more assurance of what I am saying, or correct me if I am wrong.
Thank you. PUMPDESIGNER

 

[DanDel]

I'm not sure about the value of the specific devices in your pictures, but the idea behind surge protection is for the protector to dissipate the energy in the voltage spike(by a spark, or by RC circuit snubbing, etc.) rather than across your electronic power supply insulation.

 

[busbar]

Regarding the two lower photos, they may be 600V-class gapped silicon-carbide arresters.

 

[dpc]

UL-approved secondary surge protection devices are available and are unquestionably effective when properly applied and installed. They won't protect against every possible event - a direct lightning strike for example - but they will do a good job of preventing damage to downstream equipment for many types of voltage transients.

On the down side, these devices can and do fail, generally in the shorted condition. This will not generally cause any consequential damage to your protected equipment, but will shut you down for a while.

These devices are fast enough to limit peak voltages effectively. The specs for the devices will indicate the maximum peak voltage downstream equipment will see.

In the past, there has been a lot of junk sold as surge protection. Stick with reputable manufacturers with UL-listed equipment, and be suspicious of any magical claims.

Don't forge to provide protection for ALL incoming lines, including control circuits, instrumentation circuits, telephone lines, 10Base-T lines, etc. Anything coming in from outside is a risk if you're located in a region with a lot of lightning.

 

[jsalls]

I am not sure about the higher voltages, but there are several battery backed power supplies that are usually used for computer back up that work well for control applications. The thing that is nice about them is you are actually drawing your power off the batteries during normal operation so in essence you gain a degree of separation from the main power grid. Obviously the smaller PC style ones don't supply enough power for large servo controller or anything, but for smaller applications they work great.

Good Luck!

 

[peebee]

Spark-gaps provide relatively low-tech lightning protection. It would be a real stretch to say they provide surge protection. There's lots of better technology out there for both lightning and surge protection.

 

[jraef]

Those photos are of basic off-the-shelf lightning protectors, probably Joslyn since they make and brand-label most of the major brands. They are good at protecting your motor and power control equipment, but not much good for the controls. As dpc said, adding TVSS, transorb or even MOV devices to ALL of your low voltage systems, combined with the lightning arrestors shown, will give you a fairly good level of protection. Just be aware of the failure modes of the devices. MOVs for instance have a reputation for vaporizing and can lead to colateral damage.

Here is a link to a competitor of Joslyn's since I can't find theirs anymore (I think they have changed hands recently). If you click on their "learning more" link they offer some decent basic information without a lot of hype.

http://www.deltala.com/

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