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post #1 of 8 (permalink) Old 06-21-2019, 10:14 PM Thread Starter
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Combining 2 2KVA outputs

Hi All, I have one of those Chinese 6KVA petrol generators.
The unit has (1) 3Phase 240VAC outlets and (3) Single phase 240VAC outlets
rated at 2KVA each.

My problem is I have a pump that will run happily on the 2KVA but needs about
2.7KVA to start.

Is there any danger to the generator by splicing (2) of the outlets together to give me
one 4KVA outlet.

Thanks
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post #2 of 8 (permalink) Old 06-22-2019, 08:41 AM
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I'm no expert, but I'd guess that those (3) outlets are using the different phases of the 3-phase power. As a result, there would be a voltage difference between each one.

Splicing them together would short those outputs together, damaging the generator, or at least tripping a circuit breaker and shutting down the electrical output (if you're lucky).

I would not connect the outputs together. Use a multimeter and check for an AC voltage difference between the "hot" contacts of those (3) outputs. I'm guessing you'll measure some significant voltage, indicating that they can NOT just be joined together.
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post #3 of 8 (permalink) Old 06-24-2019, 11:03 AM
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Hi Farticus,

What RedOctobyr says is correct, you have a 3 phase generator with a delta connection. It has three coils connected in such way that they form a triangle, from each vertex, a line is taken to connect one pole of the 3 phase connector. From each coil ends two lines are connected to each single phase outlet . There are 240 VAC between each pair of lines, but they are not in phase, it means that between each pair of lines an AC voltage appears, reaching its minimum and maximum values at distint times, so at anytime a voltage difference will be present between lines, this is the reason because it is not possible to joint two lines in a three phase system. Please see the attached diagram.
Attached Images
File Type: gif Delta tres fases 3.gif (12.9 KB, 4 views)
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Last edited by Osviur; 06-24-2019 at 11:18 AM.
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post #4 of 8 (permalink) Old 06-24-2019, 08:09 PM Thread Starter
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Thank you guys for your response.


Is there any way around this so that I could use this generator
opertate this pump or any device I could use on the pump to over come the start up problems


Thanks
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post #5 of 8 (permalink) Old 06-24-2019, 08:52 PM
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Can you start the pump with no load (like water), to get it spinning, then quickly add the load?

Sometimes you can add an easy-start capacitor to air conditioner compressors, to make them easier for generators to start. Perhaps something like that could be done here? Someone more knowledgeable would have to chime in.
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post #6 of 8 (permalink) Old 06-25-2019, 05:23 AM Thread Starter
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Tx Red, No its a deep well pump.
It does have a small start capicitor and I suppose I couldnt do
too much harm by fitting a bigger one and trying that.


Tx for your response
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post #7 of 8 (permalink) Old 06-25-2019, 08:57 PM
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Can the pump be re-wired for a different voltage? We had a sewer pump which, as I recall, could be wired for either 110V or 220V. This is in the US, so either 1 hot leg, or 2, on opposite phases. If the pump could accept 3-phase power, that would help get around your issue, spreading the load evenly across the generator.
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post #8 of 8 (permalink) Old 06-26-2019, 12:45 AM Thread Starter
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Personally I dont think that would be possible.


I will try a REALLY BIG capicitor and if that dont work



I will look at swapping the generator for a 3 or 4 KVA model.


Thanks for all your suggestions


Appreciated
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