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Author Topic: New 5500 watt generator shake down.  (Read 5209 times)
W8JX
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« on: November 03, 2011, 08:43:04 AM »

I recently purchased another generator and have been breaking it in and load testing it with portable heaters and watt, voltage and frequency meters. It is a Porter Cable 5500 watt rated unit with a 8900 watt surge capacity that I got cheap on clearance. It has a brush-less alternator and is powered by a commercial Briggs 10hp Vanguard motor. (brush-less alternator need less input power for same output vs brushed ones) Today was second short run. Yesterday I load tested it to 4500 watts, today it was 5300 (5287 by meters) It handled it with no fuss or straining and there still was good reserve power in engine and I have little doubt it would live up to its ratings and more. Ran load for about 10 minutes at 5300 watts while tweaking RPM to raise frequency slightly under heavy load. It goes from about 60.7 no load to 59.3 at 5300 watts. (before it would drop to 58.7 or so from 60.1 no load)

If you are looking for a no nonsense unit built with commercial parts, check them out. Easy starter, very smooth running and not very loud either. I have .8 hrs on it now and while Briggs recommends changing oil after first 5 hours and then every 100 on Vanguard motor, Porter Cable recommends 2 hrs for first change and every 50 there after for maximum service life.   
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K8AXW
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« Reply #1 on: November 03, 2011, 10:06:54 PM »

Daymn!!  That's incredible frequency stabilization!  My 5KW unit is all over the place with load change.
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K9KJM
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« Reply #2 on: November 03, 2011, 10:40:29 PM »

That is pretty good frequency stability for a small generator!

The small electric space heaters ARE a great "dummy load" for testing generators.   I get all I can cheap at garage sales in the middle of summer!    Ten 1500 watt space heaters makes a 15KW dummy load!

Fairly accurate metering is available nowadays cheap too. 

http://www.ebay.com/itm/180663382590?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

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K1CJS
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« Reply #3 on: November 04, 2011, 12:21:21 AM »

It is never a good idea to run any piece of equipment over its rated specs.  Porter Cable equipment is good equipment and can take abuse, but pushing it to do more than what it is designed to do will shorten its life expectancy.  Also, there is no need AT ALL to 'tweak' it and readjust its factory settings.  As I said, making it run beyond what its ratings are is asking for problems later.

If you need a larger size generator, get a larger size unit.  Don't make a genset go beyond what it can sefely put out.  You're just asking for problems down the road.  Drawing more from it can cause overheating, and it the windings overheat and short out, the damage may well be to more than just the genset itself.  You may end up paying for a lot more than replacing that genset--and if your insurance company finds out what was done, they may well either not pay the claim, or pay it and cancel your policy.  If that happens, you'll have a hard time getting another policy without paying for your foolishness. 
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W8JX
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« Reply #4 on: November 04, 2011, 06:13:58 AM »

It is never a good idea to run any piece of equipment over its rated specs.  Porter Cable equipment is good equipment and can take abuse, but pushing it to do more than what it is designed to do will shorten its life expectancy.  Also, there is no need AT ALL to 'tweak' it and readjust its factory settings.  As I said, making it run beyond what its ratings are is asking for problems later.

I see nothing wrong with a RPM tweak for frequency. I have a few UPS that are very frequency sensitive and if it is not in the 59 to 61 hz range it will trip them off line. (it does sometime with 3k unit) The Vanguard engine has a very sensitive governor and has good speed regulation.


If you need a larger size generator, get a larger size unit.  Don't make a genset go beyond what it can sefely put out.  You're just asking for problems down the road.  Drawing more from it can cause overheating, and it the windings overheat and short out, the damage may well be to more than just the genset itself.  You may end up paying for a lot more than replacing that genset--and if your insurance company finds out what was done, they may well either not pay the claim, or pay it and cancel your policy.  If that happens, you'll have a hard time getting another policy without paying for your foolishness. 

I have no plans to run it beyond its rated output for any period of time. I wanted to see if it could handle my electric water heater in a pinch (3800 watts as deliberately get it with lower wattage elements) and a few other things like 240v well pump which hits hard on startup.(and why I wanted high surge capacity) So, I wanted to see how it acted under load.  What is interesting with this unit is that when you switch in a 1500w load suddenly it has little effect on it. No big change in sound of sudden dip with new load. Very steady. The physical size of the alternator is noticeably bigger than other 5 to 6k units. It seems to have a lot of rotating mass momentum (field spins in a brush-less unit) as it takes longer than "normal" to stop when shut down. This momentum likely softens shock to engine with sudden increased load. On my 3K unit a big load increase hammers it good for a second. What was also surprising is after 10 minutes at 5300 watts alternator was still pretty cool to touch.

If you do the "math" I doubt you could over draw this alternator to point of damage because engine would run out of power first. (my 3k does) I considered a bigger unit of around 7k but it had limited surge capacity (it was not a Porter Cable) and would have cost more too. I wanted to balance fuel consumption vs power as well and bigger ones can get thirsty and really wanted a brush-less alternator for cleaner output too.  Typical 5k+ units have bigger engines because less efficient alternators. I also like Vanguard motors. I have a 3 year old 32hp one on a big Z-turn mower and it is smooth and sweet and uses no oil.

This unit is also CARB emission rated for California, not that I am ever gonna move there, but is looking at generators on CARB units command a price premium over non CARB ones and are cleaner running. Nice little touch too is fuel tank as it has a well around filler and it has a sump in tank (which you can see directly below filler hole) so it will run tank dry.
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W8JX
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« Reply #5 on: November 04, 2011, 06:23:09 AM »

That is pretty good frequency stability for a small generator!

The small electric space heaters ARE a great "dummy load" for testing generators.   I get all I can cheap at garage sales in the middle of summer!    Ten 1500 watt space heaters makes a 15KW dummy load!

I have about 9 of the oil filled units I got cheap at garage sales. I got them to be able to use one in most rooms until I turned oil fired hot water heat boiler for winter which is not very efficient in when it is not very cold. Once started boiler is always hot and can cause house to get a bit warm on warmer days from heat leakage from it so I use the space heaters until December usually.

Funny, I never thought of them as dummy loads for testing generators until now. They are perfect for this. 
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N2EY
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« Reply #6 on: November 04, 2011, 09:11:52 AM »

If you do the "math" I doubt you could over draw this alternator to point of damage because engine would run out of power first.

Let's do the math!

1 HP = 746 watts. So a 10 HP engine can deliver 7460 watts of power at full throttle. (In practice, that "10 HP" rating is probably at one specific speed, at a particular altitude and temperature, with everything perfect.) So in real life you won't get far beyond 5500 watts before the engine can't keep up.

In fact, the 8900 watt surge capacity must come from flywheel effect and not engine capacity.

From the ratings and description I suspect that this genset has a lot of rotating mass (rotor, engine flywheel, etc.) which is a very good thing from a frequency-regulation and surge-capacity standpoint. Makes the genset heavier and harder to crank but that's the tradeoff.

IOW, do you want a genset that:

A) you can pick up and carry some distance with no trouble

B) you can horse into the back of the van or pickup but won't carry

C) you can roll around but won't pick up without serious help

"Portable" means different things to different people.  Just like "camping".

73 de Jim, N2EY
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W8JX
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« Reply #7 on: November 04, 2011, 03:25:39 PM »

1 HP = 746 watts. So a 10 HP engine can deliver 7460 watts of power at full throttle. (In practice, that "10 HP" rating is probably at one specific speed, at a particular altitude and temperature, with everything perfect.) So in real life you won't get far beyond 5500 watts before the engine can't keep up.

Assuming 100% efficiency. Realistically I have heard that brush-less units are in the 85 to 90% efficiency range. (brushed ones are around 65 to70% or so) That being said it should run out of power between 6300 and 6700 watts out.

In fact, the 8900 watt surge capacity must come from flywheel effect and not engine capacity.

Of this I have no doubt. (both alternator capacity and momentum)
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N2EY
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« Reply #8 on: November 06, 2011, 07:15:56 AM »

1 HP = 746 watts. So a 10 HP engine can deliver 7460 watts of power at full throttle. (In practice, that "10 HP" rating is probably at one specific speed, at a particular altitude and temperature, with everything perfect.) So in real life you won't get far beyond 5500 watts before the engine can't keep up.

Assuming 100% efficiency. Realistically I have heard that brush-less units are in the 85 to 90% efficiency range. (brushed ones are around 65 to70% or so) That being said it should run out of power between 6300 and 6700 watts out.

The efficiency of the alternator is quite high; otherwise it would get hot. The real issue is how many HP the engine can deliver under real-world conditions, turning at the 3600 or 1800 RPM required by the alternator.



In fact, the 8900 watt surge capacity must come from flywheel effect and not engine capacity.

Of this I have no doubt. (both alternator capacity and momentum)
[/quote]

Exactly. surge capacity is really only meaningful when you know how long the surge is supposed to be, and what the output will do during it.
73 de Jim, N2EY
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W8JX
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« Reply #9 on: November 07, 2011, 06:22:50 AM »

I put a little more time on it yesterday with a 3000 watt load and up to a whooping 1.1 hours now. (two oil filled space heaters work great for this) I only put one gallon of gas in it so I am curious to see how long it goes before it runs dry. I will change break in oil when it gets between 2 and 3 hours on it. (OEM recommendation) Easy starter one pull does it. Very smooth running and even gas in tank is pretty smooth of surface while running.

Working on rounding up and installing a transfer relay for sub panel and a "socket" for generator feed. (work in progress) I am going to use a automatic relay based one that switches neutrals too as manual ones I have seen do not switch neutrals. I also plan to make up a 50 foot 8/4 extension cord for generator feed so I can place socket out  of weather in garage on wall between it and house where I can access it from basement to run feed to it. The long generator cord will allow me to locate generator as needed based on weather conditions.
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N2EY
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« Reply #10 on: November 09, 2011, 02:55:40 AM »

I am going to use a automatic relay based one that switches neutrals too as manual ones I have seen do not switch neutrals.

Why switch the neutral?

As I interpret the National Electrical Code, the neutral wire is specifically NOT to be switched, fused, transferred or breakered in any way. It is to be grounded at the service entrance (usually the main panel) and electrically continuous everywhere.

Just curious.

73 de Jim, N2EY
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W8JX
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« Reply #11 on: November 09, 2011, 06:18:31 AM »

I am going to use a automatic relay based one that switches neutrals too as manual ones I have seen do not switch neutrals.

Why switch the neutral?

As I interpret the National Electrical Code, the neutral wire is specifically NOT to be switched, fused, transferred or breakered in any way. It is to be grounded at the service entrance (usually the main panel) and electrically continuous everywhere.

Just curious.

73 de Jim, N2EY

For some reason with some generator applications they recommend switching neutral but not panel ground. Maybe it is because if neutral were to be raised about ground for some reason it could possible back feed into grid and shock a repair person. They even make sure that the neutral relay switches before power can be transferred via power relay.

My "guess" here is that they do not normally recommend neutral switching for most manual switching applications is due to possibility that power may be applied without a neutral return path as there is no fail safe when done manually but with a automatic change over it can be designed to not transfer power until neutral is established.

Code is kinda "funny" at times for example a 30 amp 250v, 7500 watts generator socket as four wires (leg 1, leg 2, neutral, ground) while the 50 amp version has only three wires (leg 1, leg 2, neutral)
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KE4DRN
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« Reply #12 on: November 09, 2011, 04:00:57 PM »

hi,

I've got a 5/8.5 KW Generac Wheelhouse,
it gives me similar performance, 10Hp B&S OHV.

I use full synthetic Mobil-1, do you use synthetic?

73 james
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W8JX
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« Reply #13 on: November 09, 2011, 05:10:33 PM »

hi,

I've got a 5/8.5 KW Generac Wheelhouse,
it gives me similar performance, 10Hp B&S OHV.

I use full synthetic Mobil-1, do you use synthetic?

73 james


Actually I am as I am a big believer in it. Just finished breaking in motor and changing oil in it. Using 10w30 Walmart Super Tech synthetic in it now. It is actually recommended in a Vanguard engine. (Vanguard Engines are made for Briggs in Japan by a division of Toyota) Some air cooled generator engines have been know to fail on SYN oil as it seems to disperse differently with splash lube unless they are designed to use it.  I have used Super Tech SYN in a 4cyl Jeep Cherokee since it was new and it is 11 year old now and using no oil and running well after 140k. It used to be much cheaper but not anymore.  I have also used Mobile one in another vehicle for over 22 years now as kinda a long term test. It has 200k on it and still does not even leak or leave oil drippings. (it is unbelievable it runs as good as it does still) I never have switched to SYN oil on a older/used engine or car that was run on conventional oil.
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K8IO
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« Reply #14 on: November 10, 2011, 09:45:33 AM »

That is pretty good frequency stability for a small generator!

The small electric space heaters ARE a great "dummy load" for testing generators.   I get all I can cheap at garage sales in the middle of summer!    Ten 1500 watt space heaters makes a 15KW dummy load!

I have about 9 of the oil filled units I got cheap at garage sales. I got them to be able to use one in most rooms until I turned oil fired hot water heat boiler for winter which is not very efficient in when it is not very cold. Once started boiler is always hot and can cause house to get a bit warm on warmer days from heat leakage from it so I use the space heaters until December usually.

Funny, I never thought of them as dummy loads for testing generators until now. They are perfect for this. 


That is truly scary. Man be careful. I lost a rental house to a space heater/bad wiring situation. Some knuckle head made a flying splice in the attic and buried his handywork in the cellulose insulation. First cold day of the year I get a call. The breaker is tripping and we reset it twice but now the power is out to the outlets. I said kill the breaker and I will head over. They had already shut it off. BUT it took me an hour to get there. Just in time fo find them coming out the door with the kids in tow and smoke coming out the eaves of the house. And Hubby inside trying to save stuff. I called 911 went in and ran him out. Fortunately the FD was there in 5 minutes. Saved most of their stuff. Still it was 67K in damage my insurance paid . And the house was empty 6 months. All because they didnt use a proper junction box. 
K8IO
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