Looking for a decent generator.. 5000 watts

[3930dave]

I guess I should have said "any inexpensive ways to measure THD? ".

1) Have an industrial electrician as a buddy.

2) Stay well stocked with his favourite beverage.

:drink: Rgds, D.

 

[kenmac]

What model do you have?

Had a chance to check the mod today.. I looked on the net for info ,and couldn't come up with much..
power boss 5500 mod.# is 011642-0.. I have a feeling it's going to be more than they 1st told me, but not much luck finding any info on this mod.. I found info on a GP mod but I can't find GP on my unit anywhere

 

[3930dave]

Well just looking for a device I ran across this:

from http://support.fluke.com/find-sales/Download/Asset/3497420_6112_ENG_A_W.PDF

Think I might need cleaner power for my $3,000 furnace.

I like the Fluke gear I've used, and agree with the points raised in the app note - modern appliances are often more finicky about power than their ancestors.

But, there appears to be a typo in that paper. A $1500 cost adder is off by quite a bit - today, that kind of money would buy you a heck of a power supply - in production volume that would be more like $15, if that.

Rgds, D.

 

[Larry Caldwell]

Don't forget the "Temperature Rise" spec and find out if the unit is even designed for continuous use.

I kick myself today. A few years ago, I could have bought a used Rail Reefer Service Generator. About 15-20 KW, Detoit 2 stroke Diesel and get this, 1200RPM! Weighed a ton, but reasonably priced. Now, that's a generator! Those things would just purr along, maybe for months, criss-crossing the continent. They got outlawed because they could not meet emmisions.

EDIT I just see, an outfit call "Hardy Diesel" sells these reconditioned rail units. Five and a half grand for an autostart unit. 2oKW. 20 quart oil pan! I don't for the life of me understand why anyone would buy some over priced, screaming at 3600RPM, consumer garbage unit over one of these?

Because if I bought the generator that you like, it would have cost me $50/hour to run over the last 20 years, and that doesn't include fuel or service. If the power is out for less than 48 hours, I don't even bother to get my 3600 rpm cheapie out of the barn. I have considered getting a PTO generator for the tractor, but don't think I would ever use it. The comfort level of my house doesn't change if the power goes out.

 

[Larry Caldwell]

I am very interested in in knowing more about this. This thread has me dreading a power outage since I have bought quite a bit of new electronics lately. Anything more you can tell us or point us to about this would be appreciated. On the surface it make sense, but I would like to understand more.

A solid state power supply just rectifies the input voltage and feeds it to the regulator. A square wave gives it full input voltage, while a sine wave gives it a variable input voltage. The leading edge of a square wave does contain a lot of high frequency transients, but the rectifier doesn't care.

A very simple example is the power supply in a modern LED light bulb. It just clips the maximum output voltage to the LED and doesn't bother with any other conditioning. A dimmer is a SCR (silicon controlled rectifier) that chops the input wave form into spaghetti, but the power supply doesn't care, and it does no damage at all to the light bulb. The power supply in your fancy electronics is better regulated, but has the same basic design in the input stage.

What you need to be concerned about is power spikes. When you are running in commercial power, your refrigerator is only a tiny fraction of the total load, and the power spike when it switches off can be disregarded as trivial noise. When you are running on a generator, the refrigerator can be several percent of the total power available to the system, and the motor shutting off can spike 1000 volts or more to all other equipment connected to the generator. While solid state power supplies don't care about waveform, they get cranky about over-voltage. It pokes holes in the n-p junction and fries the component.

You should have a good quality surge protector on all electronics running off of a generator, unless that is the only thing connected to the generator. You should also pay attention to grounding your generator, since most surge protectors just shunt over-voltage to ground. Even using a generator to feed a house system doesn't guarantee a good ground connection. The NEC spec for a house ground is no more than 25 ohms, so if your house ground is on the bad end of that it can limit the operation of a surge protector.

A good UPS will isolate your electronics from the supply. The good ones use line power to charge a battery and run the output off of the battery, which gives pretty good isolation to your electronics. They often have a modified sine wave output, if not straight square wave, but modern power supplies don't care about that.

Inverter power supplies have notoriously dirty power. I had to take my satellite dish off of my APC brand UPS because the output was so dirty it screwed up the clock on the dish receiver. The leading edge of a square wave output contains harmonics, and THD is a measure of how much power is contained in those harmonics. If a generator has 5% THD it means that 5% of power output is in those harmonics. Essentially that means the generator output is a "modified sine wave." A brushless rotating field generator, like even the cheapest genset, provides a nearly perfect sine wave modified only by power regulation. Most of them will clip any over-voltage, which is where rotating field THD comes from. Most DC inverting power supplies start with a square wave and massage the leading and trailing edge of the square wave to shape it closer to a sine wave. A very expensive DC inverting power supply will use electronics to generate a true sine wave output, but those are normally fairly low power and limited to laboratory applications.

The bottom lines:

1. Ground your generator
2. Use good quality surge protectors on all solid state devices powered by the generator.
3. Ground your generator.

 

[newbury]

A solid state power supply just rectifies the input voltage and feeds it to the regulator. A square wave gives it full input voltage, while a sine wave gives it a variable input voltage. The leading edge of a square wave does contain a lot of high frequency transients, but the rectifier doesn't care.
<snip the good informative lecture>
The bottom lines:

1. Ground your generator
2. Use good quality surge protectors on all solid state devices powered by the generator.
3. Ground your generator.

So what should we look for in surge protectors?
In the military we often used Tripp-Lite Isobars for fielded equipment.

It's certainly cheaper putting a good surge protector on electronics than a good UPS.

 

[Larry Caldwell]

So what should we look for in surge protectors?
In the military we often used Tripp-Lite Isobars for fielded equipment.

It's certainly cheaper putting a good surge protector on electronics than a good UPS.

You need a variety of surge protectors. I use single outlet surge protectors on my cordless phone stations, refrigerator, washer, microwave and dishwasher. The one for the base system/answering machine use one with Rj-11 connectors. I use one with Rj-11, Rj-45 and F connectors for my satellite dish receiver, TV and audio system. The bedroom TV with the old Sony sound system uses a simple power strip style surge protector. The desktop computer, monitor and the DSL modem/router is on an APC UPS, but the printer is on a separate surge protector, along with the computer speaker system. If you are short on outlets, you can get a 6-way power tap that is also a surge protector. That's what I use for the bed electronics, alarm clocks, etc. I spent $5800 for that Tempur-Pedic adjustable bed with the wireless remote controls; I'm not going to leave it unprotected. All told I have a dozen or so surge protectors in the house. I could have gone with a whole-house surge protector, but most of the local ones have multiple outlets and are kind of handy. Counting external hard drives and net appliances I have 9 devices protected at my workstation alone.

 

[newbury]

You need a variety of surge protectors. <snip>

But what qualities should we look for in a GOOD surge protector versus a piece of dog doo?

 

[3930dave]

But what qualities should we look for in a GOOD surge protector versus a piece of dog doo?

I usually look for UL 1449 certification, in a name brand like Belkin . Buy as many joules of suppression as your budget will handle (more = better).

https://en.wikipedia.org/wiki/Surge_protector#Standards

There's been discussion on here about whole-house suppressor units, can't remember the exact pricing, but IIRC it wasn't stupid high.

Rgds, D.

 

[DarkBlack]

Both brush and brushless types of standard gens produce a sine wave. Its a matter of how distorted that waveform is. My brush style gen has run all electronics in my house over the years. No surge protectors, no failures. I buy good electronic equipment which usually comes with good noise rejecting power supplies