Which Surge Protector is better?

[mkgrady]

This customer with a small office building is having problems with damaged electrical equipment. I'm told he has had to replace a couple of small motors and a fancy gas water heater in a short period of time. He asked me to see if I can find a problem with his system.

The service is 400 amps single phase, 120/240 with two 200 amp main panels. All connections in meter socket, MCBs and all circuit breakers seem good. At all points in the panels the voltage is 124/248. A little high but I'm thinking it is not damaging equipment. The power company has already been out to say the system on their end is OK.

My first thought is to install surge protection on both panels with the idea that it can't hurt and maybe it will help. Siemens makes a device that plugs in like a breaker. It takes the place of two CBs and it also contains two single pole breakers to reconnect the old circuits (there is no space in either panel). The cat # is QSA2020. There is also a unit that adds TVSS to the end of the catalog number. I'm wondering what the difference between the units is. In looking at the cut sheet the TVSS unit costs more and provides more insurance on connected equipment but I don't really care about that much. The cheaper unit is rated higher in Joules which seems better. What really has me stumped is the Intiial Clamping Level. The cheap one is rated 360 volts and the TVSS is rated 240 volts. I don't know what that means. Since the voltage is already over 240 how would that effect the one rated 240 volts?

Which unit would be better ? Any other ideas?

 

[templdl]

Before I would go through the expense hand still have the same failures I would most certainly not guess that it surge protection will solve it. I would be a bit embarrassing to charge time and material for something that will not assure that the issue is resolved.
Those are my thoughts. But if a surge protector is something that you are sold of the best place for tit is in the panel as close to the main breaker as you can install it.
But with motors I don?t think a surge protector will solve the problem. You may have an issue that the surge arrestor will not solve.
The caise of failure is way to ambiguous to attempt to draw a conclusion in my opinion.

 

[kwired]

Clamping voltage is the level at which it is going to start shunting current to ground - and assumes it is because of a surge. If clamping voltage is 240 and you are operating at 248 - I would expect it to be conducting current to ground continuously and probably will not last long. You want clamping voltage to be higher than normal operating voltage but not too high that it takes a much larger surge before it does anything.

Motor will need a pretty big surge before there is damage and you likely would have other damaged equipment from same surge. Motor could be damaged because a motor control circuit was damaged by a surge and is causing short cycling problems with the motor.

 

[mkgrady]

Before I would go through the expense hand still have the same failures I would most certainly not guess that it surge protection will solve it. I would be a bit embarrassing to charge time and material for something that will not assure that the issue is resolved.
Those are my thoughts. But if a surge protector is something that you are sold of the best place for tit is in the panel as close to the main breaker as you can install it.
But with motors I don?t think a surge protector will solve the problem. You may have an issue that the surge arrestor will not solve.
The caise of failure is way to ambiguous to attempt to draw a conclusion in my opinion.

I agree it may not solve the problem but he will be getting surge protection for the entire building and that has value. I figure it can't hurt and may save some equipment. What would you do to decipher the problem or to confirm that he doesn't have a problem?

 

[mkgrady]

Clamping voltage is the level at which it is going to start shunting current to ground - and assumes it is because of a surge. If clamping voltage is 240 and you are operating at 248 - I would expect it to be conducting current to ground continuously and probably will not last long. You want clamping voltage to be higher than normal operating voltage but not too high that it takes a much larger surge before it does anything.

Motor will need a pretty big surge before there is damage and you likely would have other damaged equipment from same surge. Motor could be damaged because a motor control circuit was damaged by a surge and is causing short cycling problems with the motor.

OK so the one rated 240 would be worthless in this case. The one rated 360 clamping volts seems so much more than the operating voltage that I wonder if it has any value. It must or Siemens wouldn't make it I guess.

 

[kwired]

OK so the one rated 240 would be worthless in this case. The one rated 360 clamping volts seems so much more than the operating voltage that I wonder if it has any value. It must or Siemens wouldn't make it I guess.

I would need to do more reasearch but I think the clamping voltage can be twice RMS voltage and you are usually good.

Remember 240 volts is RMS and not peak, so even if voltage were below 240 it is probably constantly clamping the peak of each cycle.

But you also need to know if it is clamping 240 just from line to neutral or line to line.

A good surge arrestor has protection from line to line as well as each line to neutral and is better yet if it also has protection from each line and neutral to ground.

Add: they are only intended to clamp transients and not to continuously clamp overvoltages.

 

[SG-1]

It might be worth the time to measure the voltage for a while, at least capture the peak voltages. I had voltages like that & they eventually slightly exceeded 250 volts. The transformer finally went out in a blaze of glory. The windings were shorting out & the voltage was slowing rising. This all happened over a period of months. The voltage did not stay "high" all the time. At times it would measure normal or just slightly high. What you are seeing now. It did not cause any equipment failure, well, until the the transformer failed, catastropically.

The panel is probably rated for 250 volts max. The voltage is very near that now.

One other symptom was present. Radio interference on the AM band, maybe the FM too. It would come & go.

 

[mkgrady]

It might be worth the time to measure the voltage for a while, at least capture the peak voltages. I had voltages like that & they eventually slightly exceeded 250 volts. The transformer finally went out in a blaze of glory. The windings were shorting out & the voltage was slowing rising. This all happened over a period of months. The voltage did not stay "high" all the time. At times it would measure normal or just slightly high. What you are seeing now. It did not cause any equipment failure, well, until the the transformer failed, catastropically.

The panel is probably rated for 250 volts max. The voltage is very near that now.

One other symptom was present. Radio interference on the AM band, maybe the FM too. It would come & go.

Are you suggesting a recording volt meter? One that would graph the voltage over a period of time? I have heard of that but I have never done it. I assume I would have to rent some equipment to do that? How long would I need to monitor the voltage?

 

[templdl]

I agree it may not solve the problem but he will be getting surge protection for the entire building and that has value. I figure it can't hurt and may save some equipment. What would you do to decipher the problem or to confirm that he doesn't have a problem?

This may be a long reponse but I don't think that there is a black aand white, cut and dry answer for you. It is not objective as in this is the cause of you proble and this device will definitely cure it. If there was simple answer they wouldn't need you.

Your queston is an extremely good one. While in sales I had been asked similar questions. People want you to give them a solution to their problem plain and simple. When dealing with anything such as surges arcing faults, short circuits, etc, they are events that are very hard to capture and people just don’t understand that sometimes there are no definitive answers. You either have to gather verbal information from the facility staff to see if you can put 2 plus 2 together in order to draw an assumption or you have to use an extremely expensive recording device with the chance of capturing the even. Is the latter choice practical? Probably not.
When it comes to surges what defines the surge as being damaging? Can you protection be so close that is become a nuisance.
Maybe an arcing fault doesn't have anything to do with this but it is and event of which the magnitude and duration of current can vary all over the place. To know what it was and to duplicate to come is basically impossible.
It’s the same with a bolted fault, an event that is hard to capture the magnitude of or repeat. As such you have to use you electrical knowledge to draw some assumption as to what occurred.
You don't know what disturbance caused the damage if in fact that was the cause, or the source. Did it come in through the service of may have it been an internal issue. I had a situation where an SCR in a control panel for controlling strip heaters in a plastic extruder caused enough garbage on the line that the my electronic motor starter didn't like it and went bonkers. I replace the starter with a not so high tech starter. Another issue was a breaker with an electronic trip. At 5am in the morning a 400A main breaker of an MCC tripped at a sewerage lift station which can’t be good. The electronic trip unit was an older technology peak sensing trip. I was asked to attend a meeting with the waste water people (there had to be at least 10 people around this table looking at me). Not wanting to mess around wasting time using a recorder to try to capture the even I just made the concluded that a utility PCF bank was switching which caused a voltage spike which caused a current spike high enough in magnitude to trip the electronic trip breaker instantaneously. I told them that I would replace the breaker at no charge trying to skirt the issue of getting back charges to cover the cost of havong someone reset the breaker. I resolved the issue by replacing the breaker with an old school TM breaker an never heard from them sense.
The difficulty is the fact that one may be shooting at shadows. The question is as the other guys pointed out what clamping voltage is required, and is that in fact the problem? And sometimes you just have to get lucky.
As one of the other guys said if you add something it probably would add to the protection of the facility.

You may end up considering this challenge as part of your continuing education. I look back at what I have learned over the years as well as here on this forum.

 

[mkgrady]

Thanks Temp for that post. Seems what should be done is not very straight forward. Unless someone offers a better idea I will be suggesting the surge protectors and just see what happens down the road. I still don't know which one to use but maybe someone will chime in or if not I will try to contact Siemens. I just can't imagine a factory engineer wanting to discuss a $200 item

 

[PetrosA]

Firstly, good luck with Siemens' tech support. In my experience, it's non-existant. They shunt tech support off to their distributors, so the closest you'll get to an engineer is the counter guy at your local supply house - been there, done that.

Secondly, if this were my customer, I would probably stay away from using a breaker type device to cover a 400A service split between two panels. Judging by the spec sheet I found, they seem more geared to resi applications than to light commercial. I would be recommending the TVSS unit they have that's rated for a 400A service (TPSA9040) or something equivalent from another manufacturer. It would mean twinning up to free some space in the panel, or installing a sub panel and moving circuits, but should provide much better protection and the warranty isn't limited to non-electronic devices like with the breaker surge/tvss units.

 

[Article 90.1]

Follow your customers service back to the XFMR and then go visit their neighbors who are on the same one. Ask the neighbors if they have been having any of the same issues, you might be surprised.

On the last service call like the one you are describing we noticed skid marks in the street and the dirt all out of place at the pole that the XFMR bank was on. The interesting thing is that this pole was hit a long time ago, but that is when the problems started to manifest in the buildings.

It all turned out, as we suspected all along, to be a loose neutral on the utilities side.

 

[PetrosA]

It all turned out, as we suspected all along, to be a loose neutral on the utilities side.

That should be possible to prove with a couple of multimeters.

 

[Article 90.1]

Agree, but what I left out is that the symptoms were intermittent as in not occurring while we were there. My whole point was that sometimes the answers aren't right in front of us and that no detail is unimportant when diving in to these types of service calls, or any for that matter.

 

[mkgrady]

Follow your customers service back to the XFMR and then go visit their neighbors who are on the same one. Ask the neighbors if they have been having any of the same issues, you might be surprised.

On the last service call like the one you are describing we noticed skid marks in the street and the dirt all out of place at the pole that the XFMR bank was on. The interesting thing is that this pole was hit a long time ago, but that is when the problems started to manifest in the buildings.

It all turned out, as we suspected all along, to be a loose neutral on the utilities side.

This customer is on a dedicated transformer. Loose neutral no likely as there is zero voltage difference between legs to neutral

 

[mkgrady]

Firstly, good luck with Siemens' tech support. In my experience, it's non-existant. They shunt tech support off to their distributors, so the closest you'll get to an engineer is the counter guy at your local supply house - been there, done that.

Secondly, if this were my customer, I would probably stay away from using a breaker type device to cover a 400A service split between two panels. Judging by the spec sheet I found, they seem more geared to resi applications than to light commercial. I would be recommending the TVSS unit they have that's rated for a 400A service (TPSA9040) or something equivalent from another manufacturer. It would mean twinning up to free some space in the panel, or installing a sub panel and moving circuits, but should provide much better protection and the warranty isn't limited to non-electronic devices like with the breaker surge/tvss units.

Agreed. That seems a better choice. Thanks.

 

[mkgrady]

Agree, but what I left out is that the symptoms were intermittent as in not occurring while we were there. My whole point was that sometimes the answers aren't right in front of us and that no detail is unimportant when diving in to these types of service calls, or any for that matter.

That brings me back to what I should do. A recording voltmeter seems like a big expense. Putting in the surge protection seems worth the cost even if they continue to have problems

 

[templdl]

Thanks Temp for that post. Seems what should be done is not very straight forward. Unless someone offers a better idea I will be suggesting the surge protectors and just see what happens down the road. I still don't know which one to use but maybe someone will chime in or if not I will try to contact Siemens. I just can't imagine a factory engineer wanting to discuss a $200 item

Because of the uncertainty it's best to try not backing yourself in a corner and to explain to the customer as best that you can that there are no specifics, that you will proceed with their approval, that you are not trying to "throw mud at the wall to see if you get lucky and that some will stick." Remember that you can get trapped into adding this that and the other think which may end up costing thousands of dollars. You must be up front with the customer that you are looking out for their best interest by keeping them informed and involved in decisions.
Because things are not all black and white you have to put on your diplomatic hat sometimes. Just have a plan as to how you are going to approach this.

The recommendations that the other guys presented are an excellent start to your investigation. Who knows, sometimes it's better to be lucky than good as you my discover the issue and come out as a hero. And you maybe somewhat surprised of the fact that if you weren't presented with this challenge you might not have had the opportunity to learn something new.

 

[SG-1]

Are you suggesting a recording volt meter? One that would graph the voltage over a period of time? I have heard of that but I have never done it. I assume I would have to rent some equipment to do that? How long would I need to monitor the voltage?

I would suggest monitoring the voltage for a 24 or 48 hour period. For starters just use a multi-meter with a MIN-MAX function. If you can show the POCO their supply voltage is exceeding the panel rating by a volt or two they might put a recording device of their own on it.

 

[templdl]

Thanks Temp for that post. Seems what should be done is not very straight forward. Unless someone offers a better idea I will be suggesting the surge protectors and just see what happens down the road. I still don't know which one to use but maybe someone will chime in or if not I will try to contact Siemens. I just can't imagine a factory engineer wanting to discuss a $200 item

I might add that as a former applications and sales engineer a I would not hesitate to provide support you a $5 item as I know who I'm working for and who signs my paycheck. As such expect support. Quite often you may get blown off because that support person lacks product knowledge and doesn't have the slightest clue about what an electrical distribution is.
One of my responsiblilies an application engineer was to support a 15 person customer support center. Not only was I responsible to train them but they also refered difficult application questions that they got to me. So be persistant. If you do make the call it is imparative that you know your the details and dynamics of your distibution system and why you are considering installing their product. You have to have a reason.