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Onan circuit breakers info, Emerald types and likely others

len k

Subscriber
Last Subscription Date
12/12/2018
Bit preliminary, but while reseaching info on Onan's Airpax circuit breakers I think I may have found the tech manual for these breakers. I googaled a UPG1 number from a 30amp Onan NHE breaker and found this link. IT seems these breakers are ....

"Designed using a current sensitive hydraulic magnetic principle, the APG/UPG adapts itself to many applications and environments. Temperature compensations which affect fuses and other thermal devices are not a concern. Nuisance tripping is minimized. "

Not all of breaker's model number matchs Airpax part number format so the breaker is likely propriatary , but guessing it's a reasonable chance it's the same as, or doesn't vary much from, their standard product. Common for buyers to do this so you can't go direct to manufacturer for a cheaper part. NHE 30 amp breaker Onan #320-1323 has UPG1-25775-9 listed on it. The 25775 number section doesn't fit Airpax's numbering format in the link, so I'm guessing it's the contract or Purchase Order number.

I also noticed that all the Onan breakers I have seen for Emeralds, NHM, BGM, a JB or JC, and maybe KV and KY have a delay of 62, see page 16 of below link, for amp/time trip curve.

http://airpax.sensata.com/pdfs/apg.pdf

Also found this link for Airpax breakers.
http://airpax.sensata.com/pdfs/guidetoprotection.pdf
.
 
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len k

Subscriber
Last Subscription Date
12/12/2018
I sent an email to Airpax asking for info about their breakers, amp/time trip curves. Got the email back, guess I found the right manuals, The 150% amp overload numbers are vertually idential to what I read off the graphs in the manual, old eyes. ( In graph I only looked at 150% times.).

I asked about Airpax 30 amp breaker # R 1310 , IUG1-25775-9 , 30 FL amps, 37.5 trip amps, 277VAC max, delay rating of 62, 50/60 hz. (This is the NHE Onan 30A breaker # 320-1323, I got above #'s from ebay pic of breaker)

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

Email said ....

The circuit breaker will hold 100% (30amps) of the current and it will trip at 125% (37.5 amps).
At 125%, the trip time is between 10 and 120 seconds.
At 150% (45 amps), the trip time is between 6 to 60 seconds.
200% 2-20 sec
400% 0.2-3 sec
600% 0.015 -2 sec
800% 0.015-0.8 sec
1000% 0.1-0.25 sec


Magnetic circuit breaker, with inverse time delay, trip free features, above numbers are for breaker with delay of 62.
Temp range is -40 deg C to +85deg C ( from above post ... "Temperature compensations which affect fuses and other thermal devices are not a concern. Nuisance tripping is minimized. ")

(I found above values match curve for delay 62 on page 15 of http://airpax.sensata.com/pdfs/apg.pdf
Also from graph interesting that between 100% and 125% amp overload breaker may trip, not definitely will trip.)


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

These number are INDEPENDENT of breaker amp rating, as long as it's a 62 delay airpax breaker, which I notice seems to be what Onan uses on Emeralds (NHE/BGE , NHM/BGM, ect), one JB or JC , and maybe RV, RY. I found this out by looking up Onan part numbers then looking on ebay for pics of breaker lables, with all the info on them.

Airpax sells other breakers with different delay curves ( amp/time trip curves), but so far all Onan breakers I've seen on ebay are delay 62.

This info may be usefull when retro fitting breakers to old Onans that didn't come with breakers. Like NH, CCK, ect. It's a guess, but sounds like Onan engineering found a breaker delay they liked and just used it for all. Seems reasonable as instrumenting and testing gen windings to measure temp rise is time consuming and it's easier to design new models based on old testing and keep same type breaker. Obviously this is just an educated guess and can be wrong for other gen models, use at your own risk. In another life I designed gyroscopes and their windings.

Note that the 400% overload trip time is 0.2 - 3 sec. So on average this seems good for not tripping when starting motors. Interesting that I think CCK or NH listed motor starting kw as 200% of gen's rated kw. Maybe Onan under rated them more back then??

This started out with a Staker wondering if his 6.5NHE's 30 amp breaker was bad, because his A/C short cycled and pulled a continous 42 amps for 45-60 seconds. Suspicious but could be good, from graph trip looks like ~ 7-70sec at 42 amp (140% overload). Original staker's question is Post 65 onward of http://www.smokstak.com/forum/showthread.php?t=137089&page=4
 
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nothingbutdarts

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Last Subscription Date
06/28/2020
Len,

Thank You for the information on breakers!

I have a 6.5 NH out of an RV with no breakers, it's a 1975 vintage. I don't have the tag in front of me but, I believe it rated at 52 amps. Would you recommend a 20 amp or 25 amp breaker for each leg to protect it?

Thanks!
 

PnishrPW

Registered
I would say 25A if using good breakers, 20A if ...other... 6.5 good for 27A per leg, min. Using "house" type breakers on my 6.5 NH, but only 20A units.
 

nothingbutdarts

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Last Subscription Date
06/28/2020
I was thinking about the Airpax breakers Len suggests using in this thread. I don't want any of that smoke escaping!!!!

I would say 25A if using good breakers, 20A if ...other... 6.5 good for 27A per leg, min. Using "house" type breakers on my 6.5 NH, but only 20A units.
Why only 20A breakers?
 

len k

Subscriber
Last Subscription Date
12/12/2018
Since publishing this info I looked into Onan T-009 a little.
Under motor starting, 6.5NH single phase gen has "rated KVA" of 6.5 (page 13) and Max KVA of 14, ~7 really, read disclaimer.

I would think selection of breaker amperage will depend on whether you are running 120 only output or 120/240. Reason being, in 120 only output the windings are in parelle and total load is not as bad if running 2 breakers. This assumes you won't have a starting load on both breakers at same time.

The breakers do have a WIDE (factor of 10X) time trip range for any given amerage.
200% 2-20 sec
400% 0.2-3 sec
 
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nothingbutdarts

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Last Subscription Date
06/28/2020
Since publishing this info I looked into Onan T-009 a little.
Under motor starting, 6.5NH single phase gen has "rated KVA" of 6.5 (page 13) and Max KVA of 14, ~7 really, read disclaimer.

I would think selection of breaker amperage will depend on whether you are running 120 only output or 120/240. Reason being, in 120 only output the windings are in parelle and total load is not as bad if running 2 breakers. This assumes you won't have a starting load on both breakers at same time.

The breakers do have a WIDE (factor of 10X) time trip range for any given amerage.
200% 2-20 sec
400% 0.2-3 sec
I would be running it in 240v where I have 120v to each leg of my house breaker box so I can run my 220v. well if needed. I know I'll need extreme load management if the power goes out, but I could shower if needed with a few lights running at the same time.
With that said, what size breakers would you recommend?

Thank You!
 

len k

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Last Subscription Date
12/12/2018
Hard to say, I haven't looked into it thoughly, been real busy with other things here, dad. I think being 120/240 you need to be more conservative rating the breaker, as the full load is only on one winding, and the other one can't help out as it can in the 120V only configuration. Type of load also has an effect, heater vs motor starting. With heater (steady load) I'ld rate it so the 125% rating (must trip) doesn't exceed the gen rated KVA. So ~6500/240 = 27 amps , (27/1.25) = 21.7 A , I'ld use a 20 amp breaker, usless you can find a technical justification for higher amps. I'm taking care of dad, don't have much time to think about that. If you look at trip curves , between 100-125% breaker may or may not trip!!!

Part of problem is these breakers seem sloppy, not a tight width trip curve, maybe they make newer tighter breakers. I suppose you could test the breakers say 10-20 times and again at high and low temp (10, 70, 110 deg F) to get a feel for actual trip points, or call Airpax engineering.

Got to remember these are for RVs so major load is likely an A/C unit(s) , so breaker is likely chosen assuming motor starting , not a steady load. In RV's very unlikely they can use that much power in anything but an A/C motor, most have propane water/space heaters. That may be why they have such large breakers.

Onan does use different breakers on their Emerald series gens. ei 6.5 NHE 120V only comes with 20+30 amp breakers, and on one (guess special order) a pair of 30's . But And that order was likely a customer request not Onan engineering recomendation (parts list says FA11578N sales code K285). On that one RV may have limited steady amp load with a smaller RV breaker. Same stator for both.

Same issue on 7NHM, 120V only. Same stator for all. (6800/120) = 57.7 amps. Specs 26106 & 26116 use 20&30 A breakers , others pair of 30's. specs (11439, 20105, 26115, 66115, 66173 from parts list) No idea on the significance of these specs, or where they were used/sold into.
 
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PnishrPW

Registered
I stand by my original statement, 25`s if good breakers, 20`s if cheapies... Want tight $pec breakers - Mil-$pec or Avionic$ grade.

Breakers on my NH are Siemens, ~$10/pr, spares in my spares box as well as a pr of 25`s. If I cook 'em, commonly available (Lowes/Home Depot etc). I've pushed mine pretty hard (cheap compressor/plasma cutter or compressor/mig welder at the same time) - no issues. Mine is wired 120, breakers on individual windings then paralleled.

No need to over think this, not rocket science. Len always brings a lot of good info. My suspicion is that the older NH's may be a bit more robust (windings) than the the newer NHE/M's, but probably not by any significant margin. I would look @ the 6.5NH-3CE (contractor version) for inspiration on breakers, closest relative to your NH that has on board breakers.
 

len k

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Last Subscription Date
12/12/2018
In NHE, NHM and newer 120V only , from factory they parelle the windings before the breakers.

I would be interested in what the 6.5NH-3CE (contractor version) uses, should be telling, would like part # maybe if you find it from parts list.

On 120V only NHE Onan seems to rate the total of the breaker base rating to near the rated gen amps, 20+30 A breaker. On 120V it's 6500/120 = 54 A ...... so on 240 that would be 27 A .


It's clear you can saftly use a 20 amp. Likely you can use 25 A breakers, it just relies on some info we don't have, how much safty margin is built into the winding rating. But I'm guessing NH is built with more safty margin than NHE, old stuff is usually designed better than new stuff. The 25 amp rated breaker is NOT guarenteed to trip till 31.2 Amps. This is 15% over the rated amps 27 Amp at 240V, but is likely within the saftey margin the engineers built in , 15% is not much overload.

My above breaker recomendations are based on steady state, motor starting has not been considered in sizing 20 or 25 A breakers. I suspect you need a smaller motor to comply with the ~14KVA rating. 14 is ~ 215% over rated. Typical motor starting amps are 3-4 X running, so may need max motor size of < ~ 3.5 KVA running. Onan did have a note (in T-009 maybe) about contacting Onan engineering on some A/C units. (Air Compressors have larger inertia and usually have higher starting amps, so may need to lower max motor size even more.)
 
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nothingbutdarts

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Last Subscription Date
06/28/2020
My 6.5 NH is from an RV and had no breakers on it since they most likely were in the breaker panel on the RV.
 

Zephyr7

Registered
Seems my links to airpax breaker technical info are now not working, so here's the info.
I think the airpax company was sold recently and are part of another company now. I seem to recall seeing that on a datasheet in the past several months. That might explain any info links getting messed up.

Bill
 

len k

Subscriber
Last Subscription Date
12/12/2018
Here's a few pics of technical info listed on some different model # breakers I had on my computer.
1-st pic is a summary of breaker model #'s in following pics
These pics generally came from ebay Onan ads and such. Hope someone finds info useful.
NOTE: how trip amps are 125% of full load amps !!!
 

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Zephyr7

Registered
NOTE: how trip amps are 125% of full load amps !!!
That's why we like these magnetic-hydraulic breakers for gensets. Low (relatively) trip amps, and a predictable time curve from the hydraulic part.

The little round button-type breakers on many cheap screamers are thermal breakers and are both MUCH slower and MUCH less predictable as to the trip points. They're cheap though!

Bill
 

len k

Subscriber
Last Subscription Date
12/12/2018
Been a while but I believe many of the breakers I posted pics of in post 16/17 were for BGE/NHE/BGD/NHD/BGM/NHM type gens , as that was what I was interested in at the time ..... I have a 7NHM
 

Vanman

Subscriber
Last Subscription Date
06/10/2020
My Onan 5CCK has no overcurrent protection.

My older Kohlers have Edison base plug fuses.

Keith
 

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