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Onan 7.5DKDFL - A good fit for me?


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  #41  
Old 02-26-2016, 11:57:16 AM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Quote:
Originally Posted by nothingbutdarts View Post
You need to post a few pictures of the output wires coming off the generator end. they should be bigger than #12. Run new wires connected to the gen. output wires to the aftermarket breaker box you have a picture of.

My 7.5 DKD has a ganged pair of 35 Amp. breakers mounted in the control box that I believe are factory installed. You can see the breaker on the left side of the control box under the voltage regulaton transformer on post # 29


http://www.smokstak.com/forum/showth...=140411&page=2
Yeah, I was debating about posting another picture, thinking that the one I just posted would show those wires: if you look on the back panel you'll see them. They're larger than #12, pretty sure #10, but maybe #8 (I took a bunch of pictures and figured that one of them would show up the wire gauge number, but none did).

Yes, there is that 35 amp breaker (likely double) that's original: as noted, shows up in my earlier posting (#25).

Looks like this breaker will get me what I want (can retain the panel; should be plug and play w/sizing up the wires to the 240v outlet):

http://www.amazon.com/Square-Schneid.../dp/B00DW46WMQ

That'll give me the 30 amp for 240v while still having the ability to feed a light load on a 120v.
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  #42  
Old 02-26-2016, 12:13:14 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

I can't tell from the picture in your post # 25 and I believe it has been mentioned in this thread but a breaker is not a breaker is not a breaker!!!
Onan specified different ratings than what a normal house type breaker would have for specifications so beware! A house type breaker MIGHT not tripp soon enough if the amp. load is exceded causing the smoke to be let out. LOL

I don't know if this thread was posted on the thread you have going but, good read here:

http://www.smokstak.com/forum/showthread.php?t=137737
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  #43  
Old 02-26-2016, 12:50:43 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Perhaps I'm making a bad assumption in that the main 35 amp (whatever you want to call it) that was factory installed is sufficient for protecting the generator. This add-on "sub panel" (sorry if I'm not using the correct terms) might be subject to wrong wiring and loads, but anything that could back up to that 35 amp main (whatever you want to call it) will be managed by that 35 amp main (whatever you want to call it).

Generally the State electricians are fairly knowledgeable on these things. The add-on "sub panel" was either added on by one of those folks or by the originating seller of the equipment (who could have done this as "added value").
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  #44  
Old 02-26-2016, 01:03:49 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

I'm not sure anything in the picture in your post 25 was on that DKD when it left the Onan factory and who knows who installed it.
However it could have come out of the factory that way, that I do not know. Along with that, I am NOT on of the smart guys on here!!!
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  #45  
Old 02-26-2016, 01:35:42 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

I had read that thread that you provided (thank you; I believe I did so before, but I just now re-read it). It seems that it centers around the MAIN "breaker." I am not touching the 35 amp main "breaker" on my unit, I'm leaving it as what I believe is likely the factory "breaker" (this was spec'd as an industrial-use unit, not out of an RV).

The existing configuration on the sub-panel has 3 circuits: 20 amp 240v and (2) 20 amp 120v. These add up to 60 amps. In my mind this doesn't seem right, but then again I'm not an electrician. I'm looking for 3 circuits as: (1) 30 amp 240v and (2) 15 amp 120v. Also a combined 60 amps. Is the existing wrong? I don't know. If it's OK then what I'm proposing should also be OK (as long as I wire that 240v outlet with a minimum of 10ga wire). I could look to exclude one of the 120v circuits, which would leave me at 45 amps, and up-size the wiring to the sub-panel (this would actually be better than what currently exists).
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  #46  
Old 12-06-2017, 10:26:24 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Hi, folks!

Well, been a long time but I'm getting close to throwing the switch in testing this generator hook-up. All the connection stuff has been vetted with an electrician. BUT...

Now I'm getting nervous. Wondering how my various electronic bits of equipment will take to the power produced. I am concerned about various items with electronic circuitry, such as:

- Water system's backwash filter (has electronics)
- Cook stove (it's propane, but has some electronics in it)
- Clothes dryer (also propane; brand new)
- Clothes washer (electric- though not expecting to run if running under emergency backup-up power- but if long-term requirement then perhaps)

My computer equipment runs off of UPSes.

Well pump I'd expect wouldn't be real touchy.

From what it sounds like THD is a concern, with folks saying that one wants to be 5% or less. What kind of THD spec would a generator like this have?
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  #47  
Old 12-06-2017, 11:11:24 PM
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Default Re: Onan 7.5DKDFL - A good fit for me?

Most electronics now simply rectifies the AC in the power supply - so they don't really care a lot about the incoming AC. 50 Hz - 60 Hz, 100 volts-250 volts is a common spec on switching power supplies now.

Probably the only thing that might be an issue is the UPSs - someone was just saying they can be finickety about the HZ value and switch back to battery when the generator slows for a second taking up a big load (They are thinking the power has failed because the zero crossing was a fraction of a second later). Just plug them in and check that they stay on the power and don't squawk when a load is dropped on the generator. See if they can be tuned to be less sensitive to frequency variations.

From the sounds of it, I think the THD is marketing red herring to sell special "low THD" generators. To be honest - this Onan is likely going to have a much cleaner waveform than any box store genset out there.

Take a look at this thread - especially Joe Ramas post #10
https://www.smokstak.com/forum/showt...14#post1441814
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  #48  
Old 01-08-2018, 11:29:17 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Replaced my coolant temperature sensor. Gauge is now operable. But...

Switched generator over to feed main panel and I'm only registering 103v. Had not checked voltage for some time, but back when I got the unit everything checked fine.

When I installed the plug (plugs into a box that is wired to my main panel) I had thought that I might have over-tightened the ground terminal. Pulled it apart and, yes, it won't tighten- it's stripped. I suspect this is what was causing my problems. Ordered a new plug (opted for a Hubbell this time; first one was a Leviton [apparently I'm not the only one who has has run across problems with these]). Fingers crossed that it's not the generator that is at fault.
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  #49  
Old 01-09-2018, 12:25:18 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Get yourself one of these Kill A Watt meters and check HZ. HZ should be 60 which is 1,800 RPM, If RPM is low voltage could be low. Get locally at hardware store, Home Depot or here :


https://www.amazon.com/P3-Internatio...kill-a-watt+ez

Last edited by nothingbutdarts; 01-09-2018 at 12:29:59 AM. Reason: added info.
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  #50  
Old 01-09-2018, 08:43:02 AM
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Default Re: Onan 7.5DKDFL - A good fit for me?

on a 7200 watt rated Homelite with a 21 HP Kohler engine.....
It came with 30 amp breakers and twist lock with 15 amp sub fuses for outlets

I changed outlets to push button 20A breakers [and new 20 amp outlets]
I isolated the neutral changed to a 4 prong twist lock, 10 gauge portable cord.

works great with interlocking breakers.

while the earth ground and the neutral go to
the ground and bonded neutral in the main panel
[electrically the same place]
they serve two different uses.

the neutral carries the neutral currents
the earth ground keeps you safe[r]

a 3 wire hook-up doing both is not safe by today's standards.
generators kill people every year. make it as safe as it can be.
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Last edited by armandh; 01-09-2018 at 09:07:58 AM.
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  #51  
Old 01-09-2018, 02:24:05 PM
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Default Re: Onan 7.5DKDFL - A good fit for me?

Yeah, when the plug is connected the neutral is connected via the main panel.

I probably should have measured Hz, but I was distracted by the low voltage. I didn't want to keep running with low voltage so I stopped everything.

Plug is due in another week, but won't be able to get around to trying it for another couple weeks. Meanwhile rain and high winds are expected in the next couple of days, wouldn't you know it! (circumstances have kept me from being proactive)
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  #52  
Old 01-09-2018, 03:35:34 PM
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Default Re: Onan 7.5DKDFL - A good fit for me?

When you do get to measuring voltage again be sure to measure it at the input to the gen internal breaker if it seems off. Many a time a poor connection somewhere has caused a lot of needless work to be done when all that was necessary was to tighten up a connection. Also check your volt meter against your house power to make sure that the volt meter is OK. Cheers Dan
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Old 01-09-2018, 05:17:42 PM
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Default Re: Onan 7.5DKDFL - A good fit for me?

Quote:
Originally Posted by DieselBound View Post

Plug is due in another week, but won't be able to get around to trying it for another couple weeks. Meanwhile rain and high winds are expected in the next couple of days, wouldn't you know it! (circumstances have kept me from being proactive)
Situations such as this a Big Block or maybe a Dual Quad from Nutty's Grill is recommended. A 4 Banger at the very least!
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  #54  
Old 01-09-2018, 10:15:27 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Quote:
Originally Posted by BigBlockChev View Post
When you do get to measuring voltage again be sure to measure it at the input to the gen internal breaker if it seems off. Many a time a poor connection somewhere has caused a lot of needless work to be done when all that was necessary was to tighten up a connection. Also check your volt meter against your house power to make sure that the volt meter is OK. Cheers Dan
Thanks for that tip. Post breaker I've got the plug, the connection for the receptacle and then the connection at the house's main breaker panel. Electrician did the wiring for the receptacle and the main breaker panel, so am hoping that that's good.

I've got a Fluke DMM, so good there.
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Old 01-10-2018, 10:39:06 AM
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Default Re: Onan 7.5DKDFL - A good fit for me?

please keep in mind that local codes may differ but the national code allows
a means to prevent inadvertent cross connection [interlocking breakers]
for connection of a portable generator [ie plugs in] so....
keep it "looking" some what portable [not in a shed it cannot be removed from]

permanent stand by generators require a transfer system.
much more expensive.

but since your electrical work was done by an electrician [as far as it went]
doing the rest safely falls to you
be sure you understand how you are wiring things.
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  #56  
Old 01-10-2018, 01:54:22 PM
len k len k is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

THD in brushless gens......... Different types of brushless gens. Apples and oranges.

-- Onan types with electronic voltage regs
-- cheapie capacitor regulated types from big box stores --- these can have high TDH and spikes at the top of voltage sinewave.

------------------------------------

But a switching power supply should happily eat any scrappy power, it rectifies it all to DC first, then uses it. Computers use switchers as power supply, computer UPS were frequently square wave output

In transformers and motors the higher frequency harmonics that THD has end up as waste heat. So they run a bit hotter. But I haven't heard of any failing from that.

The voltage level of the harmonics is lower than the fundamental 60 hz, so the 60 hz voltage dominates and clocks and motors run at their 60hz speed

Last edited by len k; 01-10-2018 at 02:06:01 PM.
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Old 01-10-2018, 02:55:24 PM
Wayne 440 Wayne 440 is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

DISCLAIMER - the following is based on my experience, yours may vary.

I have "a few" years of experience around engine generator sets, from 500W to 1MW. I cannot think of any residential sized instance where the THD of the supplied power from a generator set created a problem. Most of the issues I found were frequency related, and confined to one brand of UPS device that apparently requires 60.000000Hz input or it goes nuts. The solution was a trashcan to receive those UPS devices, and replacing same with a better product.

In the absence of a UPS device, my experience has been that so-called "sensitive" devices such as computers, TV sets etc. will run from just about anything that happens to come out of a generator set as long as it is even close to 120V, 60Hz. If it is AC, and will light a 100W incandescent bulb without (very much) visible flicker, I don't hesitate to plug in and use it.
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Old 01-10-2018, 03:07:12 PM
DieselBound DieselBound is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

Quote:
Originally Posted by armandh View Post
please keep in mind that local codes may differ but the national code allows
a means to prevent inadvertent cross connection [interlocking breakers]
for connection of a portable generator [ie plugs in] so....
keep it "looking" some what portable [not in a shed it cannot be removed from]

permanent stand by generators require a transfer system.
much more expensive.

but since your electrical work was done by an electrician [as far as it went]
doing the rest safely falls to you
be sure you understand how you are wiring things.
I did extensive research. I'm using a interlock kit: UL listed and acknowledged/accepted by my local utility company.

The professional electrician wasn't aware of the need to break the neutral bond at the generator I explained it to him and he's now "aware." I am 99.999% confident that things are, messed up plug aside, wired correctly.

Wayne, yeah, my limited understanding is that frequency seem to be the biggest thing. Last I'd checked this generator held frequency very well. One of my UPSes was really perturbed with the low voltage; not surprised; when I get the current issue resolved I'll see if it then is OK (if not I'll contemplate whether I want to swap it out- it's nearly 7 years old).
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Old 01-10-2018, 03:22:35 PM
len k len k is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

I only bumped into knowing about THD when I called manufacture and asked what their gen was specd at . Think he said 15- 20 % THD. ....WOW That's HIGH !!!!!! Mostly a peaked sinewave with additional spikes on the peak. It was a capacitor regulated gen. Porter maybe??

Those THD numbers are on par with a APC computer UPS I have that outputs modifed square waves

This was NOT a quality gen, was a cheapie one. Onan gens are in vastly superior catagory of quality.

Quote:
Originally Posted by DieselBound View Post
The professional electrician wasn't aware of the need to break the neutral bond at the generator
Reminds me of electricians that used to cut the green wire off cables when wiring up a breaker box and branch wiring......
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Old 01-11-2018, 08:30:32 AM
armandh armandh is offline
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Default Re: Onan 7.5DKDFL - A good fit for me?

UPS[es] and generators

some UPS are overly sensitive to power HZ fluctuation, as I understand it,
they use a shift in the zero crossing interval to indicate loss of grid power.

for my basement servers I went to an "always on" double conversion UPS.

this type converts grid power to DC and back to sign wave AC for the load.
the batteries [on mine] feed a DC/DC up voltage converter.
the two DC supplies are then paralleled. [no switch over]

lt is a lightly loaded 1KW commercial unit bought "refurbished" over 7 years ago,
and on its second set of batteries, still going just fine. [knock wood]
__________________
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by using this free advise, you, your heirs, etc
absolve, save, and hold harmless the advisor.
CAVEAT EMPTOR
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Last edited by armandh; 01-11-2018 at 04:58:43 PM.
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