output voltage crowbar

[3dAngus]

Brown out conditions are usually regarded by many as being the most damaging to electronics.

Someone will surely argue the srmantics of this but it is generally true. Mostly because more current is drawn.
I had a brownout at my house that was isolated to an individual housing ptoblem that did about $8500 in damages and it was paid for by the power company.

The PDUs I've worked with on raised computer floors protecting $millions in equipment are all being replaced now days and are quite common. The parts can be salvaged from them for this specific application and if I recall it right they were scrap metsl prices. Keep in mind though they had a large center core transformer of copper but were still just a few $hundred. You could salvage then scrap.

This is only the kind of extra protection one usually does if they rely on generator power rather then one who uses it for emergency backup.

 

[ctfjr]

It seems to me that if the OP's concern is protecting against an overvoltage condition a true 'crowbar' circuit would be a relatively inexpensive solution. A crowbar (iirc) basically 'shorts out' the circuit almost instantly when the overvoltage point is reached.
An appropriately large triac would be needed as well as some current limiting device (resistor of some sort) to limit the shorting current to a value over the breaker setting but below the triac's rating. I'm sure a google search of 'electrical crowbar' will yield plenty of typical wiring diagrams, including ones that allow for some brief transients (if desired). The trick is finding the components cheaply (in my youth I used to search the local junkyard that took in scrap computer equipment).

 

[Triple Jim]

This is a great thread, and it caused me to do a lot of thinking about a regulator failure causing the output to climb to 160V, but the more I think about it, the less I'm worried about it hurting anything in my house. 160V is only a 33% overvoltage. My computers, TVs, and video equipment are all on UPSs. I'd notice that that stuff had gone to UPS power and start investigating in a short time, I'm sure. Things like refrigerators would take a long time to be damaged by a 33% overvoltage, if it ever hurt them. I might go as far as an alarm in my house to alert me if the voltage gets over 130 or so. That could be good for grid power too, to catch things like an open neutral, or lineman goofup. But I'm 55 now, and can't remember ever having anything damaged by high voltage, other than by lightning.

 

[o1951]

It seems to me that if the OP's concern is protecting against an overvoltage condition a true 'crowbar' circuit would be a relatively inexpensive solution. A crowbar (iirc) basically 'shorts out' the circuit almost instantly when the overvoltage point is reached.
An appropriately large triac would be needed as well as some current limiting device (resistor of some sort) to limit the shorting current to a value over the breaker setting but below the triac's rating. I'm sure a google search of 'electrical crowbar' will yield plenty of typical wiring diagrams, including ones that allow for some brief transients (if desired). The trick is finding the components cheaply (in my youth I used to search the local junkyard that took in scrap computer equipment).

If the concern is just surge protection, you can buy whole house units that are UL/CSA/ANSI certified for nominal cost.
1 style uses 2 breaker slots and just plugs in. The other is a box - that is what I have because I did not want to sacrifice 2 slots.

Protects my electronics on genset and on utility - great protection from lightning hitting powerlines nearby.

If there is ever an incident that might be considered electrical, best to have all approved stuff, no home brew - insurer and fire inspector take a dim view.

Breaker plug in style:
Square D by Schneider Electric QO SurgeBreaker Secondary Surge Arrester Takes 2 Load Center Spaces

Model # QO2175SB
Internet # 100202111
Store SKU # 290076
$57.98


External box style:

Leviton Residential Multimedia Surge Protection Panel

Model # 005-51110-PTC
Internet # 203003389
Store SKU # 910567
Store SO SKU # 162677

$127.00 /EA-Each

• PRODUCT DESCRIPTION
  This Leviton Residential Multimedia Surge Protection Panel mounts at the service entrance in your home to provide protection against transient surges that enter through AC power lines, telephone lines and cable TV/satellite feeds. This surge protector features a J-box enclosure with pre-punched knockouts for easy installation in a breaker panel.

• Transient voltage protection for AC power line, 4-wire phone line and cable TV and satellite feed
• Real-time LED diagnostic visual indicator shows suppression status for each protected phase
• J-box enclosure with pre-punched standard knockouts for easy installation at any breaker panel
• Flush cover and surface mount brackets for versatile installation
• UL 1449 3.0 Edition listed
• CSA listed and ANSI certified
• MFG Brand Name : Leviton
• MFG Model # : 005-51110-PTC
• MFG Part # : 005-51110-PTC

SPECIFICATIONS

ANSI Certified	Yes	Assembled Depth (in.)	2.22 in
Assembled Height (in.)	8.13 in	Assembled Width (in.)	4.75 in
CSA Listed	Yes	Connection type	Panel Mount
Electrical Product Type	Secondary Surge Protection	Joules	3400
Manufacturer Warranty	10-Year Limited Warranty	Maximum Amperage (amps)	4800 A
Product Depth (in.)	2.22	Product Height (in.)	8.13
Product Weight (lb.)	3.2	Product Width (in.)	4.75
Returnable	90-Day	UL Listed	1-UL Listed

 

[Triple Jim]

When I did my measurement of regulator current while idling the engine on my 003A recently, I disconnected the regulator output briefly with the generator at 1800 RPM, and the output voltage was right around 160 on each 120 leg.

Oops, I goofed. It was not 160 on each 120V leg, it was about 260 total. I was looking at the meter today and realized my mistake. Now I've even less concerned about hurting anything in my house if the regulator fails.

 

[Jimc]

Good to know jim, thanks

 

[o1951]

Jim, some parts of the country are running 130/260, so it should be ok. Supply house I use stocks 130 volt bulbs.
I recommend some type of approved surge protection at the main panel.

 

[Triple Jim]

I don't mean to doubt you, but I've never heard of any part of the US grid that intentionally supplies 130Vor 260V. I have known about 130V bulbs for 30 years or more, but only as extra-long life "rugged" bulbs. I'm a fan of surge suppression hardware.

 

[quickfarms]

The ac voltage depends on how it is measured and weather the gauge or meter goes to the peak over the years I have heard it referred to as 110/220 or 120/240 or on a rare occasion 130/260 it is all actually the same for alternating current

 

[1800 Diesel]

I'm with 3DAngus--we bought a Tripplite LC2400 power conditioner a couple years ago....just plug it in to your line outlet close to where your plazma TV, computers or electronics are and use the outlets on the conditioner for the protected devices.

Haven't had any issues with it. I believe the price was about $200. This model is rated for 2400 watt load and has 6 AC outlets. It's in a nice enclosure roughly 8-10" cube.

 

[Jasonz in MO]

View attachment EffectsOfOvervoltage.pdf

Attached is a report I found concerning the effects on electronics due to overvoltage. Looks like a lot of devices can handle brief voltage spikes as well as sustained durations. Table 5.1 is probably the most interesting. When my VR wasn't functioning and the control winding in the CVT1 transformer was open the voltage at the convenience outlets were 160-161vac. I didn't measure the output at the main lugs; I assumed they would be the same. Originally, my concern was overvoltage due to VR component failure but frequency is also a consideration.

Line conditioners and equipment protection devices are probably the way to go for your expensive loads like TV’s, computers and ham gear.

I’m still thinking about something to kill the genset to prevent it from smoking any of its expensive internal components.

 

[Triple Jim]

Thanks for the link, Jason. I skimmed through it and will take more time later to read it.

Because of my confusion (above), I plan to re-check my 003A's output with the regulator disconnected sometime soon. I'll post what I find out.

 

[leedawg]

Many electronics are designed with auto switching power supplies to easily run on 240 volts. All of Europe is 240.. Any way ive never put much thought into this personally but I would have to agree with everyone else the best protection would be tripping the main breaker. On the 004 and up this would be very easy to do in fact they have this protection built into them already and a fault indicator to alert you to this condition. So its a moot point.

Why not just wire up a relay between the 120 legs on the mep 003 lugs, and then have your 20 dollar voltage monitor close that relay if the voltage goes out of its limits hence creating a short between the 120 volt legs which will almost instantly kick out the main breaker on the generator hence opening up the circuit so no power flows from the generator any more?

That's what I would do pretty simple and straight forward.

 

[Triple Jim]

As promised, I when I ran my MEP-003A today, I disconnected the regulator at terminal 17 so that no control current flowed through the control windings of CVT1. I used a Fluke 87 to measure the output voltage, and found 168v from each line to L0, and 336V from L1 to L3. No particular point here, I just wanted to share the information.

 

[Jimc]

Thanks jim gor that test. Atleast we know what worst case is for over voltage

 

[Triple Jim]

You're certainly welcome. I had it going for several minutes without regulation, and the 120V control components held up fine. That's a good sign, I think.

 

[leedawg]

So Jim can you plug your 1080p 70 inch led TV in tomorrow and run the same test so we can have a full report of what happens

Thanks for the real world data though it's Interesting....

 

[Triple Jim]

Sorry, my TV isn't that big, so no, I can't do that, but I know at least some new TVs will run on anything from 100 to 240VAC, so as long as you send the right 70" TV here, I'll try it.