question about parallel generators

[scottsnider]

I have a 2300 generator that has a run speed of 1800 which is not enough to run my AC (30A). So my question is what is the smallest size generator I could use in parallel to bring it up to run the AC? I will be honest and say I don't know the AC need but it will run off my 120a house current at home without struggling. Common 3 prong plug at home. I have a Coleman hybrid trailer that is end to end 21 ft, says 18 for the box.

[DrewE]

Circuit breakers (well, the ones you're likely to encounter) are thermal or thermal-magnetic. On a generator I suspect often they're just thermal ones, as I think that's what the little push-button ones nearly always are. Household ones in panels are thermal-magnetic.

Anyway, both of these allow some overcurrent for short periods of time. For household breakers, there are standards that specify how quickly they must trip for various conditions, from basically instantaneously for a serious overcurrent (as in a short circuit, several times the rated current of the breaker) to holding indefinitely (at or below the current rating at standard ambient temperatures). This is a very good thing, as for instance starting a large motor in an appliance would otherwise cause the breaker to trip most every time; the instantaneous inrush current is very often greater than 20A.

A 30A receptacle is rated to conduct 30A more or less indefinitely, and you're allowed to load a 30A receptacle with a 30A load. The 80% derating applies to "continuous loads", which are loads that operate at their maximum current continuously for three hours or more. An RV is not a continuous load per the NEC, so the 80% derating does not apply here.

There are magnetic circuit breakers that react instantaneously to current over some approximately exact threshold, but they are used pretty much exclusively for specialized applications. One example is (some) theatrical lighting circuits. The difference between the breaker types is how they (traditionally, at least) are actuated: thermal breakers are tripped when a bimetallic link carrying the current heats up and bends, while magnetic ones trip when the current, which flows through an electromagnet of some sort, produces a strong enough magnetic field to activate the mechanism. Thermal-magnetic breakers have parts so the bimetallic strip also can trip through magnetic means if the current is very high.

[BFL13]

Apparently many of our members are off camping instead of being glued to "tech issues" here on their computers. Who let them do that?

Meanwhile, this is a mystery. It seems there are losses when synchronizing, but not clear if that has anything to do with this.

Also the gens and the parallel kits have circuit breakers. At what watts (current--heat?) do they pop? If you are only allowed 24A on a 30a receptacle, does that mean they use a 25A breaker with a 30A receptacle? If not, why not? (How do they know how long you will run your appliance?)

But then if the breaker were such, how could it handle the rated surge, way above the "running" rating? Is it a timing thing for "slow-blow" with surges?

There has to be all kinds of good info about all this, but it is not easy to find on Google. So let's get those slackers back from camping, and get them back on this forum so we can find out! 😞

[road-runner]

It seems the NEC in the US has an 80% rule, so you can only load a 15A to 12A etc. 3600 x 80% = 2880.

The "80% rule" has context. It applies only to "continuous loads", where the maximum current is expected to continue for 3 hours or more. Absent that, circuits can be freely loaded to the maximum allowed by the wire size and OCPD.

[BFL13]

Here is one 2300/1800. There are others.

https://www.homedepot.com/p/RYOBI-Bluetooth-2-300-Starting-Watt-Super-Quiet-Gasoline-Powered-Digital...

It says "Running Watts" for the 1800 figure on it.

--I do not know more about why you don't get double when paralleling. The table from the Briggs and Stratton manual for my P2200 is what it is.

There is also some info in the Champion website about combos. They mention that you can combine a smaller gen with a bigger one, but it is not advantageous (or similar wording) and it seems to turn on which kits will fit which gens. They have different kits for different gens. Each kit has certain receptacles. I think (?) the key to the mystery is in what those receptacles in the kits are rated for, but not sure about that.

Somebody posted in another thread on this that you can parallel some gens with no kit, but do it with DIY wiring, and in that case you get more total power?--but I have no details.

It would be nice to know more about all this. Not much info in the various brands' ads.

https://www.championpowerequipment.com/parallel-kit-selector/

OK the parallel kit for the above 1800w gen has two 30A receptacles, and it says it will double the output of one gen. (30 x 120 =3600.) I don't know if you can really use a 30A receptacle to get 3600 watts. Must have correct ampacity wiring too AFAIK.

Electricians on here must know. What say? -- EDIT! -80% rule has 3600 at 2880 for loading a 30A

https://www.homedepot.com/p/Inverter-Generator-Parallel-Kit-AUN9230PK-S/203695188

EDIT some more--- the B&S kit also has 30A 120v receptacles, but they still say it will do 3000w max with two 2200s. 2 x 1700 =3400, so where did the 400 go is the question, especially if a 30A can do 3600.

https://www.briggsandstratton.com/na/en_us/product-catalog/generators/portable-generators/inverter-p...

EDIT again! It seems the NEC in the US has an 80% rule, so you can only load a 15A to 12A etc. 3600 x 80% = 2880.

[Tom_M1]

wa8yxm wrote:
Now .. I would not recommend you parallel it period
WHY. when you parallel two AC generators they must be precisely in phase. if they are out of phase bad things happen. These small ones do not phase lock well and may well go BOOM when you hook in the 2nd one.

The OP has already stated that his generator is an inverter type. Most inverter generators can be paralleled with the same model with an optional parallel cable.

[map40]

BFL13 wrote:
"Running speed" is assumed to mean "continuous watts". So the 2300w gen does 1800w.

In ads for paralleling, they say it will double the output, but this is false. Two of those will not do 2 x 1800 = 3600. However, two of those might still be enough to run your air conditioner. Needs more info on the A/C's draw.

EG, a B&S "P2200" gen is rated at 1700w continuous. Paralleling those gets you maximum output of:

two P2200s = 3000 watts (not twice 1700 notice!)
one P2200 and one P3000= 3000w (which is more than the 3000's cont.)
two P3000s = 4800 watts

So you see how that works. It has much to do with the actual ratings of the receptacles on the "parallel kit". Each generator brand has its own versions of those and they vary.

In the table above, you see that the 2200 and 3000 combo is limited to 3000 same as for two 2200s. This is because you have to use the parallel kit that has the connections that fit the smaller gen parallel plug-ins. Same with odd size combos of other brands like Champion.

OK, now I want to know. Could you explain a little more on how do you loose power when in parallel? I have combined in parallel different sizes and brands and have not experienced that loss, but maybe I did not check in depth. I do know that the power consumption gets ditributed according to capacity. If I connect a 2200 with a 3500 the load will not distribute evenly, it will distribute according to the capacity.

[wa8yxm]

He said RUN SPEED.. NOT run watts But since I included inverter generators in my post it still stands.

[Groover]

wa8yxm wrote:
YOu mentioned the Run Speed of 1800 (1/2 of 3600) This suggests to me it is a standard traditional Generator. NOT an inverter Generator for they do not have a "Run speed" they change speed as the load changes.

Now .. I would not recommend you parallel it period
WHY. when you parallel two AC generators they must be precisely in phase. if they are out of phase bad things happen. These small ones do not phase lock well and may well go BOOM when you hook in the 2nd one.

Now DC generators.. Well DC is always in phase.. (Unless you hook it up backwards)

Really big generators (Think Niagra Falls Power Plant) those can be effectively phase locked.

Inverter generators do it automatically for the most part

But I do not think that one can be phase locked for parallelling.

BUT.. There is hope

Vector Electronics makes a battery/inverter/charger system desgned to do what you need. The inverter syncs to your generator and when it senses a sudden load it kicks in.. then drops back to charge the battery.

I do not have a bookmark,, SOrry.

The op doesn't use units with a lot of his numbers. You are assuming 1800RPM. I suspect that it is 1800watts. Read his notes that way and see if it makes more sense.

[ib516]

Groover wrote:
I would look into putting a Micro-Air easy start on the air conditioner. Expensive but still less than a second generator and a lot less trouble. It worked for me and there are a lot of YouTube videos on it. Easy start

What he said ^

[wa8yxm]

YOu mentioned the Run Speed of 1800 (1/2 of 3600) This suggests to me it is a standard traditional Generator. NOT an inverter Generator for they do not have a "Run speed" they change speed as the load changes.

Now .. I would not recommend you parallel it period
WHY. when you parallel two AC generators they must be precisely in phase. if they are out of phase bad things happen. These small ones do not phase lock well and may well go BOOM when you hook in the 2nd one.

Now DC generators.. Well DC is always in phase.. (Unless you hook it up backwards)

Really big generators (Think Niagra Falls Power Plant) those can be effectively phase locked.

Inverter generators do it automatically for the most part

But I do not think that one can be phase locked for parallelling.

BUT.. There is hope

Vector Electronics makes a battery/inverter/charger system desgned to do what you need. The inverter syncs to your generator and when it senses a sudden load it kicks in.. then drops back to charge the battery.

I do not have a bookmark,, SOrry.

[Groover]

I would look into putting a Micro-Air easy start on the air conditioner. Expensive but still less than a second generator and a lot less trouble. It worked for me and there are a lot of YouTube videos on it. Easy start

[opnspaces]

Basically you need a second 2000w generator.

[bikendan]

scottsnider wrote:
I am sorry yes my Generator is a inverter type.

It would help if you posted make and model since i don't know of any 2300w inverter generator. 2200w yes.
Also not all inverter generators can be paralleled.

[LittleBill]

scottsnider wrote:
I am sorry yes my Generator is a inverter type.

generally you want to buy the same brand and size, so they share the load equally