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Power spike protection for CNC shop.

partsproduction

Titanium
Joined
Aug 22, 2011
Location
Oregon coast
A few months ago an electric spike fried the spindle drive of one of my CNC lathes. I'm looking for protection from such incidences in the future.
I was told by a man in the business that a type that is basically a transformer will even out the spikes and limit damage, for from $500 to $2500 per machine (Of which I'd only equip the 3 most expensive).
But talking with a retired engineer who was an engineer in a large plant years ago he said a single point between incoming power and the main breaker that uses back to back zener diodes would limit the peak power at whatever value is set and anything over that value would be dumped to ground, plus would be much cheaper and cover the whole shop.
Do any of you know about such a setup and whether it would meet the need?
Thanks for any info in advance,
parts
 
I cant help but I am going to watch this, seems SRP here in the valley in the last 6-8 months been screwing up some equipment. 2 cars wrecks, a cut cable and a bad main transformer . lost another drive and 2 power supplies.
I haven't lost anything in the last 10 years at this place till recently. lately the power goes out every friday night or weekends and summer isnt here yet.
 
Here is a discussion and diagram; Using diodes on a relay for spike protection | All About Circuits

This guy is talking about 240V single phase while my power is 230V 3 phase, and the diodes would be back to back so that both directions, + and - are clamped at the set value. My service is 200 amp and that runs the whole shop with 12 machines and two welders,plus many smaller power sippers.

There are only two of us working in the shop but often one guy runs two and sometimes three CNC machines. The spike in November ended up costing over $30,000 which insurance covered almost 95%
I told the adjuster I'd find protection and now she is asking me to keep my word, which is understandable.
My retired engineer friend made it sound like the back to back diode setup is not some guess, but a common way to limit damage to the diodes themselves if there are spikes (though that was the first time for us in 30+ years). It seems to me that if they are effective they must be sold as a ready to wire box with led's to indicate if there has been a spike that went un-noticed or if either of the diodes had been damaged.
 
Maybe these could be useful?

Reading the information it almost sounds like what the engineered was describing, he said the maximum power would be set and so does the ad, and it said there should be a light that indicates that it's doing it's job.

As to transformers (Forgive my ignorance) I assumed running incoming 230 V 3Ph in, increasing the voltage and then reducing it back again to 230V would have a taming effect in that it adds lag which might break up the characteristics of the spike, But I was told I'd need to buy one for each machine, and at a minimum of $500 that would mean we might be bale to protect maybe 3 machines.
 
You will need huge zeners to protect your premise.

There are devices called MOVs that are designed for the job. I think it stands for Metal Oxide Varistor. In normal circumstances it presents a high resistance, but when a spike comes along it breaks down and absorbs the extra energy.

Most spindle drives have small ones, they look like a flat disk with two wires. There are special ones for protecting telephone lines that plug into krone connectors.
 
Partsproduction. A few thoughts from different perspective, for what it's worth.

From information given: One burned up spindle drive, 30 year shop, 230V 3Φ 200A service, 30K drive repair.

Any other info about the incident? There was only one machine and spindle drive damaged?

No other equipment was harmed? How old is the drive that failed? From what country is the machine in question?

In order to get the best longevity from electronic controls and drives, it's best to pay close attention to your electrical service,
system type, and operating voltage, as well as what system type and voltage that the machine equipment was built for.

When you say 230V 3Φ, that sounds like 240/120 3Φ 4W Delta to me, with a wild/Hi leg (208V to ground)?
Is that what the shop has? Does your 120/240V 1Φ loads come from the same panel?
Or do you have a 208V 3Φ 4W Wye system, 120V from each leg to ground?

The reason I ask, is because most drives are built for a Wye system input. When you feed them with a delta system,
the system voltage is not symmetrical to ground, which can cause stress on the drive parts.
European and Asian equipment is oftentimes built for a slightly lower voltage, than our standard delta system voltages.
It would be a good idea to check the service voltage and system type, as well as the equipment nameplates or manuals.
Mismatched systems will usually run, OK, but can be running right near the voltage limits, and stressing the drive components.


The grounding and bonding of the service and machines/equipment is just as important. If not done adequately,
it can introduce additional difficulties. Surge suppression equipment is pretty ineffective if it doesn't have a solid earth reference.
Before you obtain suppression modules, check your earthing, bonding and grounding systems.

In order to select the correct suppression modules, you need to know your service type, Wye or delta and the voltage it runs at.

Transformers are also good at knocking down surges as well, but again, what type you would use, depends on your service and equipment.

SAF Ω
 
I have on of these for my house/garage.

https://www.homedepot.com/p/Intermatic-IG-Series-Type-1-or-Type-2-Surge-Protective-Device-White-IG1200RC3/205878345

Clearly not the same protection as a device that costs a couple thousand per machine, but a little piece of mind and a small investment which might appease the insurance company. I'm sure 3 phase models exist. These are basically the same technology that exists in a surge protector you'd put under your desk for a computer, but with a lot more capacity, and an indicator to tell you when it's used up.
 
Forget about home depot...

There are many commercial devices.

One is a load center with devices built in, single or 3 phase.

Others are add on that either have a dedicated breaker for the device while others simply parallel the load at the device or panel.

Not zener diodes but clamping devices that turn on at given voltage and absorb smaller spikes and pull the breaker for larger ones.

Common devices in remote communications sites where very sensitive high dollar equipment is protected.

This is old technology and no need to "home build" or use home depot consumer grade.

Another option is to ask the insurance guy to check with their engineering and underwriters to provide a list of acceptable devices.

If they are providing discount or requirement for device then they should have a specification sheet that defines the specific device minimums to qualify.

Then look for devices that meet or exceed those.

Do this FIRST.

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
I use a series of TVSS/noise filtering components between the service entrance and each machine, one at the service entrance, at the branch circuit panel and then a combination TVSS/noise filter at each machine. Attenuation is a series of devices not one, there are a few white papers on the subject. Installation is critical to proper function, the TVSS wires need to be as short as possible with minimal bends, ideally mounted directly to the panel/at the entry to/in the machine. You might look at the Eaton or ABB commercial surge protection and power conditioning products. I would use at least 3 levels of suppression, there are various pros/cons as to type of devices used/implemented, but MOVs are the primary component at the service entrance. Layering of TVSS systems and grounding is key to proper function. I previously was in Tucson, and lightening strikes were very common with frequent surges/power outages. When the power grid came back online there were also wide variations in voltages. I had a counter at the service entrance which would also record the voltage spikes, so it was clear that the system were doing its intended purpose.
https://www.eaton.com/content/dam/eaton/services/eess/eess-documents/sa01005003e.pdf
http://www.eaton.com/ecm/idcplg?Idc...eAs=1&Rendition=Primary&&dDocName=EPODPNBD017
https://library.e.abb.com/public/d0daeef3da6fe159852573ad005b7234/1SXU430003B0201.pdf
Current Technology Surge Protection - ABB Power ProtectionABB Power Protection
 
Thanks for all the responses.
What is clear to me now is that the problem is far too complex for my simple mind to fathom, and I'll need to find a dedicated "Splainer" to come in and tell me what I need, and probably an electrician to install it.
mksj, your answer sounds much like the TIE Fanuc World answer, and if I can figure out how to answer the engineers questions we'll probably go that direction.
 
Afterthought

The fellow at TIE suggested that the back to back zener diode SPD would serve well for the particular problem we had. Apparently 80% of transients are from inside the business, not from the incoming line like mine. The type 1
SPD's are not best for internal spikes I'm told, they need the transformer type at each machine. (If I'm wrong please feel free to say so, I'm just learning this stuff)

They are the type "2" SPD's (Surge Protection Devices)and the power surges are caused by built up power that has no where to go when a contactor is opened.
For protection from external spikes like lightning and line accidents though the type 1 may be cheap insurance.
UL Type 1 Surge Protective Device (SPD): 20 kA (PN# STXR240D05) | AutomationDirect

Thanks,
parts
 
There is a funamental misunderstanding that gets into the discussion by what I consider to be careless use of words.

The particular words are "surge" and "spike". Some of the references used them interchangeably, but that is not correct.

A "spike" is a short duration mains disturbance, usually a higher than normal voltage, lasting typically for less than one cycle of power frequency. It carries a high "power" but does not typically amount to much "energy". It can cause arcing, and breakdown of components, but usually does not directly result in burning type damage. Burnout of components can result from the damage the spoke causes, as mains current may follow a path the spike established. (Direct lightning strikes are an exception to the "not much energy" rule)

A "surge" is anything longer. A surge can easily cause burnout of components, since it both causes the breakdown, and provides the "follow current". The total energy available may be quite high. I have seen "surges" cause fairly large MOVs to simply "disappear", vaporized by the power in the surge. A surge may not even be that high in voltage, but may be high enough to damage sensitive items such as heaters, contactor coils, servo drives, some computer equipmnt, etc.

Spikes come from switching transients, lightning, etc. Surges come from faults that change the mains voltage, generator faults, wiring problems such as high resistance neutrals, cases of "line crosses" where a higher voltage feeder at perhaps 4160V or 7200 V falls onto lower voltage wires such as 480V or 230V wiring, etc.

MOVs, zeners, spark gaps, and the like, are ONLY good against "spikes". None typically have the power capability to handle a longer "surge". These types of protector depend on drawing enough current for a short time to hold down the voltage, but they dissipate the power, and cannot do that for long. MOVs are actually rated for their energy capability, what they can take without excessive damage.

Naturally, the protection against the two is different. It is very difficult (expensive) to prevent damage from "surges", and fairly easy and relatively low cost to prevent damage from "spikes".

The typical MOV systems are good against "spikes".

Surges really require the actual voltage to be adjusted, such as with a tapped transformer, or a power conversion system that isolates the input from what is supplied to the facility, such as motor-alternator sets, UPS arrangements, or the like. Usually not practical economically for other than very high value systems.
 








 
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