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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Don Davis on April 06, 2015, 05:09:17 pm

Title: Protect equipment from excess voltage
Post by: Don Davis on April 06, 2015, 05:09:17 pm
Forgive this nube question but is there any way to build an alarm that will sound if the voltage to an amp rack or distro is too high? Or shut down to protect the system kind of like over current protection but for voltage level instead.

I ask because I had a bad experience this past weekend. The DWP of a military base provided 150KW genny for the Easter production I was providing for. They provided the generator and Cal50 cabling up to my 50A single phase distro and a stand by operator. My assistant who is a registered electrician, assisted the DWP tech with the hook up. He watched the tech take a meter out and check the genny output then give a thumbs up to energize the system.

Part way into sound check one of the monitor amps goes down. Assuming a normal failure I brought out the spare amp and rewired. About 15 minutes to curtain Iím at FOH and someone runs back and says smoke is coming out of one of the amps. I immediately got that sick feeling in my stomach and knew what was happening. I started powering down then ran and got the tech out of his truck and told him heís frying my equipment. He got his meter out and it reads almost 200V per leg.

He simple didnít set it up correctly. Iím not sure what he checked with the meter since I was out front managing the set up at the time.

I know this is my fault for not verifying what this tech metered and the words Iíve heard on this forum many times about metering before you power up were blasting in my head but in the heat of battle with a tight set up schedule stuff happens so please donít beat the crude out of me for my mistake.

Besides never taking ANYONEís word on power ever again, what else would you guys suggest. I do have voltmeters installed in the backs of my main amp racks but when theyíre tucked away they canít be seen. How about a strobe, bell etc. something to get my attention possibly for over or under proper voltage. I lost 2 - XTI4000s and possibly an iTech4000 so far that I know of. Iím grateful it didnít take out any FOH gear or all the bandís backline. All my amps are set up to run on 120V/15-20A.
Thanks
Don
Title: Re: Protect equipment from excess voltage
Post by: TJ (Tom) Cornish on April 06, 2015, 05:25:28 pm
Forgive this nube question but is there any way to build an alarm that will sound if the voltage to an amp rack or distro is too high? Or shut down to protect the system kind of like over current protection but for voltage level instead.

I ask because I had a bad experience this past weekend. The DWP of a military base provided 150KW genny for the Easter production I was providing for. They provided the generator and Cal50 cabling up to my 50A single phase distro and a stand by operator. My assistant who is a registered electrician, assisted the DWP tech with the hook up. He watched the tech take a meter out and check the genny output then give a thumbs up to energize the system.

Part way into sound check one of the monitor amps goes down. Assuming a normal failure I brought out the spare amp and rewired. About 15 minutes to curtain Iím at FOH and someone runs back and says smoke is coming out of one of the amps. I immediately got that sick feeling in my stomach and knew what was happening. I started powering down then ran and got the tech out of his truck and told him heís frying my equipment. He got his meter out and it reads almost 200V per leg.

He simple didnít set it up correctly. Iím not sure what he checked with the meter since I was out front managing the set up at the time.

I know this is my fault for not verifying what this tech metered and the words Iíve heard on this forum many times about metering before you power up were blasting in my head but in the heat of battle with a tight set up schedule stuff happens so please donít beat the crude out of me for my mistake.

Besides never taking ANYONEís word on power ever again, what else would you guys suggest. I do have voltmeters installed in the backs of my main amp racks but when theyíre tucked away they canít be seen. How about a strobe, bell etc. something to get my attention possibly for over or under proper voltage. I lost 2 - XTI4000s and possibly an iTech4000 so far that I know of. Iím grateful it didnít take out any FOH gear or all the bandís backline. All my amps are set up to run on 120V/15-20A.
Thanks
Don
Your ITech should be OK - it's universal voltage.

The big lesson here is you need to test under load.  Presumably the neutral conductor was either disconnected or poorly connected, which causes the voltages to change based on the relative loads on the phases.  A load test will reveal that.  Get a couple 1000W PAR cans or heaters and plug them in to the same phase of your distro.  If you can vary the voltage more than a couple volts, you have a problem.

Not that this is a huge consolation, but you should work to powering as much of your gear at 240/208v as possible.  In addition to balancing the load which helps generators out a lot and preventing harmonics on the neutral wire, you will never lose gear to a lost neutral wire in the future, as your gear isn't using the neutral.
Title: Re: Protect equipment from excess voltage
Post by: Frank DeWitt on April 06, 2015, 05:27:31 pm
You can buy voltage sensor relays and set them to close a contact at what ever voltage you chose.  The contact could ring a bell or light a light or disconnect the power to your gear. 

You can also get equipment from SurgeX and others that includes under and over voltage shutdown

Under-Voltage Auto Shutdown  Adjustable from 90V to 110V   
Over-Voltage Auto Shutdown  Adjustable from 130V to 150V

http://surgex.com/products/rackmount-sequencers-product-line.html
   
Title: Re: Protect equipment from excess voltage
Post by: Mike Sokol on April 06, 2015, 05:34:22 pm
Forgive this nube question but is there any way to build an alarm that will sound if the voltage to an amp rack or distro is too high? Or shut down to protect the system kind of like over current protection but for voltage level instead.

I've never seen anyone do this for pro-sound, but it's a common problem with the RV industry. Progressive Industries makes a EMS (Electrical Management System) with relays that will monitor voltage and ground, and disconnect you from power if something goes out of spec (over 140 volts, I think). They make one rated up to a 50-amps at 120-240 volts with a 50-amp "stove" connector. I might consider something like this for my own sound rig if I was doing a bunch of shows powered from military generators. Even if the neutral opens up in the middle of a show, the EMS Surge Guard will open up the relay contacts to protect your gear.

http://www.progressiveindustries.net/ (http://www.progressiveindustries.net/)

As a side note, none of these EMS products will detect or disconnect you from a RPBG (Reverse Polarity Bootleg Ground) outlet. But that's nearly impossible to create on a 120-240 split phase feed.   
Title: Re: Protect equipment from excess voltage
Post by: John Roberts {JR} on April 06, 2015, 05:53:16 pm
Life is cruel teacher.... she gives the test first and then the lesson... Learn from this grasshopper...

JR
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 06, 2015, 06:48:25 pm
Life is cruel teacher.... she gives the test first and then the lesson... Learn from this grasshopper...

JR

Yes JR it is. One would think at my age the lessons would be diminishing but they seem to get more expensive.
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 06, 2015, 06:54:47 pm
Your ITech should be OK - it's universal voltage.

The big lesson here is you need to test under load.  Presumably the neutral conductor was either disconnected or poorly connected, which causes the voltages to change based on the relative loads on the phases.  A load test will reveal that.  Get a couple 1000W PAR cans or heaters and plug them in to the same phase of your distro.  If you can vary the voltage more than a couple volts, you have a problem.

Not that this is a huge consolation, but you should work to powering as much of your gear at 240/208v as possible.  In addition to balancing the load which helps generators out a lot and preventing harmonics on the neutral wire, you will never lose gear to a lost neutral wire in the future, as your gear isn't using the neutral.

The tech did mumble something about a loose wire, probably the neutral as you suspect.

One channel on an iTech was cutting in and out for the balance of the event. To the shop it goes.
I don't believe the XTIs are dual voltage capable. I currently have 6 in my mix racks.
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 06, 2015, 07:03:22 pm
You can buy voltage sensor relays and set them to close a contact at what ever voltage you chose.  The contact could ring a bell or light a light or disconnect the power to your gear. 

You can also get equipment from SurgeX and others that includes under and over voltage shutdown

Under-Voltage Auto Shutdown  Adjustable from 90V to 110V   
Over-Voltage Auto Shutdown  Adjustable from 130V to 150V

http://surgex.com/products/rackmount-sequencers-product-line.html

Looks like a good solution but might be too pricey for multiple circuits
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 06, 2015, 07:06:35 pm
I've never seen anyone do this for pro-sound, but it's a common problem with the RV industry. Progressive Industries makes a EMS (Electrical Management System) with relays that will monitor voltage and ground, and disconnect you from power if something goes out of spec (over 140 volts, I think). They make one rated up to a 50-amps at 120-240 volts with a 50-amp "stove" connector. I might consider something like this for my own sound rig if I was doing a bunch of shows powered from military generators. Even if the neutral opens up in the middle of a show, the EMS Surge Guard will open up the relay contacts to protect your gear.

http://www.progressiveindustries.net/ (http://www.progressiveindustries.net/)

As a side note, none of these EMS products will detect or disconnect you from a RPBG (Reverse Polarity Bootleg Ground) outlet. But that's nearly impossible to create on a 120-240 split phase feed.

The EMS-HW50C looks very interesting and may provide distro level protection. We are almost exclusively on military bases. Sometime on generators sometimes on house power.
I bought my own generator last year to help prevent these problems but it isn't big enough for the rig I used this past weekend.
Title: Re: Protect equipment from excess voltage
Post by: Mike Sokol on April 06, 2015, 07:26:49 pm
The EMS-HW50C looks very interesting and may provide distro level protection. We are almost exclusively on military bases. Sometime on generators sometimes on house power.
I bought my own generator last year to help prevent these problems but it isn't big enough for the rig I used this past weekend.

Yeah,  the EMS-HW50C is the hardwired version, so you can put your own connectors on it that would plug right into your distro from genny power. They've tested these units all the way up to plugging them into a 480-volt generator (the first time it was accidentally on an oil-field generator) and it just shuts off the output power and shows over-voltage without damaging itself. I have both the 30-amp/120-volt and 50-amp//120/240-volt versions in my shop which Progressive Industries sent me last year to evaluate, and I've not been able to blow them up yet. ::)

I'm sure the PI-EMS would shut down AC power with a reset time-out if the neutral failed on your generator feed or it went over-voltage on one of the legs for any other reason. Let me know if you want to talk to their engineering department about your application and I'll hook you up. 

FYI: The street price is around $350 including shipping. http://www.amazon.com/Progressive-Industries-HW50C-Electrical-Management/dp/B003AN1UA8
Title: Re: Protect equipment from excess voltage
Post by: Guy Holt on April 06, 2015, 09:51:55 pm
I bought my own generator last year to help prevent these problems but it isn't big enough for the rig I used this past weekend.

What generator did you get?

Guy Holt, Gaffer
ScreenLight & Grip
www.screenlghtandgrip.com
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 07, 2015, 10:59:25 am
What generator did you get?

My local rental yard was retiring all of their Honda ex5500s. I was able to get one a great price.
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 07, 2015, 03:23:51 pm
Hi Mike,
There are not a lot of specs on their site so yes I'd like to talk with them about it. That'd be great.
I'd be interested in the hi-low trip points, reset times and how they operate with floating vs bonded neutrals.

Thanks!
Title: Re: Protect equipment from excess voltage
Post by: Guy Holt on April 08, 2015, 11:24:10 am
My local rental yard was retiring all of their Honda ex5500s. I was able to get one a great price.

If it were a Honda EU6500 or EU7000 you could parallel it with another of the same  generator from your local rental house for a combined 100A output.  You can parallel the EX5500s but it is more difficult and you would need to find the same or similar model which is getting harder and harder these days.

Guy Holt, Gaffer
ScreenLight & Grip
www.screenlightandgrip.com
Title: Re: Protect equipment from excess voltage
Post by: Mike Sokol on April 08, 2015, 12:38:48 pm
The EMS-HW50C looks very interesting and may provide distro level protection. We are almost exclusively on military bases. Sometime on generators sometimes on house power.
I bought my own generator last year to help prevent these problems but it isn't big enough for the rig I used this past weekend.

I just sent you a PM with the contact info for the President of Progressive Industries. We've just discussed power protection for the Pro-Sound industry, so he's expecting your call. Even though their products are built for RV (camper) protection, they could be a really good solution for your situation.

From the factory the EMS has a 15-second time-out after a voltage problem, which can be changed to 2 minutes and 15 seconds with a jumper. The 2+ minute shutdown is for air conditioner compressors needing time for the freon pressure to drop before starting "hot". The EMS over-voltage trip point is 132 volts, and the low-voltage trip point is 104 volts. Those hi-lo trip points are set in the processor code and can't be changed in the field. However, that seems reasonable for sound system protection. 

Please report back to the forum once you get to talk to him and we'll see if their RV technology is a good fit for the Pro-Sound industry. I think it looks pretty good at first blush.
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 08, 2015, 02:53:39 pm
If it were a Honda EU6500 or EU7000 you could parallel it with another of the same  generator from your local rental house for a combined 100A output.  You can parallel the EX5500s but it is more difficult and you would need to find the same or similar model which is getting harder and harder these days.

Guy Holt, Gaffer
ScreenLight & Grip
www.screenlightandgrip.com
Thanks Guy, I hadn't thought about paralleling them.
I could probably pick up a second EX5500 from the same rental yard but it might make sense for us to rent a bigger unit when needed. The 5500 handles our smaller gigs very well plus I use it at the house for backup power.
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 08, 2015, 03:22:47 pm
I just sent you a PM with the contact info for the President of Progressive Industries. We've just discussed power protection for the Pro-Sound industry, so he's expecting your call. Even though their products are built for RV (camper) protection, they could be a really good solution for your situation.

From the factory the EMS has a 15-second time-out after a voltage problem, which can be changed to 2 minutes and 15 seconds with a jumper. The 2+ minute shutdown is for air conditioner compressors needing time for the freon pressure to drop before starting "hot". The EMS over-voltage trip point is 132 volts, and the low-voltage trip point is 104 volts. Those hi-lo trip points are set in the processor code and can't be changed in the field. However, that seems reasonable for sound system protection. 

Please report back to the forum once you get to talk to him and we'll see if their RV technology is a good fit for the Pro-Sound industry. I think it looks pretty good at first blush.

Thanks Mike, I spoke to them today, they were most helpful. It sounds like the EMS-HW50C is a really good choice for my application. I'm going to order one today and install it. Ill report back after I've used in in the field a few times.
Thanks everyone!
Title: Re: Protect equipment from excess voltage
Post by: Stephen Swaffer on April 08, 2015, 08:31:35 pm

.... and how they operate with floating vs bonded neutrals.


Not to hi-jack the thread since this has been discussed thoroughly in other threads, but a floating neutral really has no place in a pro audio setup-so for audio use that parameter is really not needed.
Title: Re: Protect equipment from excess voltage
Post by: Mike Sokol on April 09, 2015, 08:33:48 am
Not to hi-jack the thread since this has been discussed thoroughly in other threads, but a floating neutral really has no place in a pro audio setup-so for audio use that parameter is really not needed.

Stephen is correct. But note than many portable generators under 5KW have a floating neutral which you'll need to bond to the chassis ground.

I know that the EMS-HW50C will check for a floating neutral and shut down AC power if it detects one. 
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 09, 2015, 03:37:05 pm
Looks like a well made piece of gear. I'll try and install it tonight and test it on shore power. Just moved into a new warehouse so we'll have to install a 50A breaker and outlet first.
Title: Re: Protect equipment from excess voltage
Post by: Mike Sokol on April 09, 2015, 08:35:54 pm
Looks like a well made piece of gear. I'll try and install it tonight and test it on shore power. Just moved into a new warehouse so we'll have to install a 50A breaker and outlet first.

Very good. What kind of connectors do you use for your distro?
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on April 10, 2015, 04:15:09 pm
Very good. What kind of connectors do you use for your distro?

Input is Cal50. We installed the unit between the Cal 50 and the breaker panel that is in the distro. Powered it up and checked the display. It showed L1 & L2 Volts, 0 Amps, HZ and a code that says that everything it checks is wired correctly. I think this is going to be a winner for us. The next test will need to be in the field under real conditions.
Title: Re: Protect equipment from excess voltage
Post by: Mike Sokol on May 06, 2015, 05:32:42 pm
Input is Cal50. We installed the unit between the Cal 50 and the breaker panel that is in the distro. Powered it up and checked the display. It showed L1 & L2 Volts, 0 Amps, HZ and a code that says that everything it checks is wired correctly. I think this is going to be a winner for us. The next test will need to be in the field under real conditions.

Don, any reports back from the field? I may just install one myself if you like it...
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on May 07, 2015, 04:54:09 pm
Don, any reports back from the field? I may just install one myself if you like it...

Hi Mike,
No, all of my gigs since have been smaller and on wall outlets.
I have a couple coming up in June and July, that will be my test.
I'm still pulling damaged amps out of the rack for repair, total is 4 down so far.
Money well spent if the device helps protect against this in the future.
Title: Re: Protect equipment from excess voltage
Post by: Kevin Bayersdorfer on June 06, 2015, 01:59:20 am
I just wanted to chime in on this and my one experience. I am small potatoes and don't use distro's yet. This one gig was one that I was actually playing in the band also. It was at a local VA hospital. They were providing us with a simple 120v genny since it was down by the Hudson River and now house power around. The two VA electricians show up with a 5kw emergency genny, they start it up and from my experience in working on small engines I notice it's overspeeding. I immediately pull out my meter and sure enough 168v out of the edisons...I grab the event coordinator and tell him I am not plugging my gear into that. They all hemmed and hawed then came to me, you have any ideas? Yeah let me adjust the idle, ok they say, but we have been using this generator for years like this. Haha well I guess that's why all your power tools worked so fast. They both looked at each other like oh crap yeah.... Just goes to show meter everything.
Title: Re: Protect equipment from excess voltage
Post by: Allen Smith on August 30, 2015, 10:14:30 pm
I've never seen anyone do this for pro-sound, but it's a common problem with the RV industry. Progressive Industries makes a EMS (Electrical Management System) with relays that will monitor voltage and ground, and disconnect you from power if something goes out of spec (over 140 volts, I think). They make one rated up to a 50-amps at 120-240 volts with a 50-amp "stove" connector. I might consider something like this for my own sound rig if I was doing a bunch of shows powered from military generators. Even if the neutral opens up in the middle of a show, the EMS Surge Guard will open up the relay contacts to protect your gear.

http://www.progressiveindustries.net/ (http://www.progressiveindustries.net/)

As a side note, none of these EMS products will detect or disconnect you from a RPBG (Reverse Polarity Bootleg Ground) outlet. But that's nearly impossible to create on a 120-240 split phase feed.

Mike,

Its not clear to me from your post, have your or do you actively use one of these Progressive products for live audio?  I am very interested in some sort of protection for a 20k audio system and led lighting rig.
Title: Re: Protect equipment from excess voltage
Post by: Tim McCulloch on August 31, 2015, 09:20:35 am
Mike,

Its not clear to me from your post, have your or do you actively use one of these Progressive products for live audio?  I am very interested in some sort of protection for a 20k audio system and led lighting rig.

Take a good look at your LED lights.  I'd bet they are "universal" power:  100-250v. 50/60 cycle.

Mike was responding to Don Davis, who had a over-voltage situation that took out some gear.  The product they're discussing is made for the RV/camping industry and that's also one of Mike's safety passions so it was a good fit for discussion and investigation.

Now I'm an RV guy (small, can't afford a Class A on a sound guy income) as well as a sound guy.  My observation is that almost all venue power, shitty as some of it is, tends to be better than campground power pedestal service.  In 30+ years of providing portable audio services I recall only 1 instance of over voltage at a venue (outside line problem); and 2 times when generator power was bad (neutral bonding).  Two other over-voltage incidents happened because some moron (me, the first time) didn't adequately/correctly meter the genset output.  Only one of these resulted in equipment damage.  That's 5 incidents out of literally 2,000 gigs and only 1 that killed any gear (and mostly fuse replacements, although a couple items were toasted).

While I think anything that keeps us, the performers and audience safer is a very good thing, I think spending $ on this is a lower priority than implementing proper electrical safety practices and having good test gear.  The likelihood of gensets "gone wild" is very small and proper testing will generally reveal bad neutrals.  With the advent of universal power supplies in much of our audio equipment over-voltage is becoming less of an issue, too.

If you've had repeated issues with over-voltage service I think it should be discussed with clients and you should consider adding language in your contract to make the client liable for renting crappy generators or employing shade tree electricians that hook up incorrectly.  But your power chops need to be thorough and complete to make this stick...

On the RV side, I'm considering this unit because I have no control over the testing and maintenance of the power distribution system (unlike in audio).

Have fun, good luck.

Tim Mc
Title: Re: Protect equipment from excess voltage
Post by: Mike Sokol on August 31, 2015, 11:28:33 pm
Mike was responding to Don Davis, who had a over-voltage situation that took out some gear.  The product they're discussing is made for the RV/camping industry and that's also one of Mike's safety passions so it was a good fit for discussion and investigation.
And if you look at the OP question, he often does gigs on military bases and has had issues in the past with generators being hooked up incorrectly and at least one time creating an over-voltage condition that destroyed some gear. So if I was doing that gig on a regular basis I think something like a Progressive Industries EMS would be a worthwhile investment. Also note that the OP was interested in something that would warn you of an overvotage condition. But the real answer is you really can't be watching some kind of meter all the time. So if your gigs give you power that could be wired wrong or lose a neutral, then an automatic protection device is called for. But your meter (and knowing how to use it) is still your best friend before hooking up to AC power.

But yes, RV campground power is REALLY bad since there will be dozens or even hundreds of other "temporary" RV hookups in your vicinity, some of which were installed by DIY guys who don't even know what a volt meter does and who can't wire a light switch.
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on November 21, 2015, 11:32:48 pm
Just wanted to give an update on how the EMS-HW50C has worked in the field.
We did an event last night powered by a 25KW genny, first time using my distro with the EMS installed. The system was 4 dbl 12 tops, 8 SRX718 subs, 8 iTech 4000s and 6 XTI wedge amps plus FOH and misc gear.

We properly inspected and tested the generator and its output before hooking up. There was about 200' of feeder passing through at least one spider box before it got to me. There was some site lighting and other things I had no control over on the same generator.

During set up we pushed the system really hard with a DJ providing the music. The EMS went into time out. At first I didn't realize what had happened then the system came back on line. We checked the meter and everything looked fine. We went to check the generator and it was still set properly. My best estimate to the cause was that I had too many sub amps on the same leg and it was reacting to the heavy bass. We balanced things out and didn't have any problems.

The EMS may be a bit too sensitive to use on hard driven gigs. But, it did exactly what it was supposed to do. Did I mention that I hate generator gigs.

Title: Re: Protect equipment from excess voltage
Post by: Tim McCulloch on November 22, 2015, 12:53:22 am
Just wanted to give an update on how the EMS-HW50C has worked in the field.
We did an event last night powered by a 25KW genny, first time using my distro with the EMS installed. The system was 4 dbl 12 tops, 8 SRX718 subs, 8 iTech 4000s and 6 XTI wedge amps plus FOH and misc gear.

We properly inspected and tested the generator and its output before hooking up. There was about 200' of feeder passing through at least one spider box before it got to me. There was some site lighting and other things I had no control over on the same generator.

During set up we pushed the system really hard with a DJ providing the music. The EMS went into time out. At first I didn't realize what had happened then the system came back on line. We checked the meter and everything looked fine. We went to check the generator and it was still set properly. My best estimate to the cause was that I had too many sub amps on the same leg and it was reacting to the heavy bass. We balanced things out and didn't have any problems.

The EMS may be a bit too sensitive to use on hard driven gigs. But, it did exactly what it was supposed to do. Did I mention that I hate generator gigs.

Don't power your I-Techs from the EMS device.  They are "universal" from 100-250v, 50 or 60 CPS.  Use your voltage-protected feed for the rest of your stuff.
Title: Re: Protect equipment from excess voltage
Post by: Don Davis on November 22, 2015, 11:14:13 am
Don't power your I-Techs from the EMS device.  They are "universal" from 100-250v, 50 or 60 CPS.  Use your voltage-protected feed for the rest of your stuff.

Thanks Tim, makes perfect sense.