GENERATOR QUESTIONS FOR YOU EXPERT ELECTRICIANS

[CobyRupert]

I saw something on wiring a zig-zag configuration on a MEPS 12 terminal type genset. It was not well explained. I am interested and will try and find something to make me understand it. Always interested in understanding how things work as opposed to just believing what I am told.

Zig-zag!!

I only heard of that configuration used as a grounding transformer.

I can get you through resistive grounding schemes, but if you're using zig-zag transformers for grounding, (or zig-zag gensets ??), that's beyond me!!

 

[Industrial Toys]

I only had heard of it for Rolling Papers! Maybe a scheme hatched after smoking some wacky tobakee.

Reconfiguring an MEP generator set for single phase 12/24 - YouTube

How to do it but not how it works.

 

[CobyRupert]

:laughing: :laughing: :laughing:

 

[nyone]

That video shows how to modify a 3ph only generator into single phase. The mep802 that i own has single and 3ph capability just by turning a switch. Its due to extra windings in the head.

 

[CobyRupert]

I got a crazy generator.
It is a 4 cylinder gas/propane generator, liquid cooled, but only produces 3000 watts. However, this is the crazy part, it produces that power at either 1 or 3 phase depending on what you want. I know there are many 3 phase generators, but I have never seen one so small in Kw's that can have either.

That video shows how to modify a 3ph only generator into single phase. The mep802 that i own has single and 3ph capability just by turning a switch. Its due to extra windings in the head.

...but the 3 phase kW/kVA rating is different than the 1ph kW/kVA rating....right?

 

[aczlan]

I saw something on wiring a zig-zag configuration on a MEPS 12 terminal type genset. It was not well explained. I am interested and will try and find something to make me understand it. Always interested in understanding how things work as opposed to just believing what I am told.

So do MEPPS sets typically have more windings than a run of the mill 3 phase alternator? Not that I yet understand the phase implications.

On the smaller MEP gensets (like nyone has), they ran all the leads out to a reconnection box so it can run either single or 3 phase.
The one in the video, IIRC had the leads brought out, but the genset was only setup for 3 phase, so you could only load it to 60% capacity.

That video shows how to modify a 3ph only generator into single phase. The mep802 that i own has single and 3ph capability just by turning a switch. Its due to extra windings in the head.

Yep, on your genset they ran all the leads out to the reconnection box so it can run either single or 3 phase. Most "civilian" gensets don't need that capability, so they save money by keeping those leads shorter and connecting them inside the generator head.

There was a thread on Steel Soldiers that went along with that video, I will see if I can find it.

Aaron Z

 

[nyone]

Of corse its rating is different not 1/3rd though.

 

[aczlan]

...but the 3 phase kW/kVA rating is different than the 1ph kW/kVA rating....right?

Not if you reconnect the wires to the generator head, if you do that, you will have the same watts available for single phase as it had for 3 phase. That was the point of doing that, more capacity at 120/240 single phase.

Aaron Z

 

[Industrial Toys]

I'm still going to try and understand this. But wording is important. Because a generator CAN be switched from 3ph to single, does not necessarily mean it will work to full capacity. It might, but it also might not.

I am just thinking out loud, but maybe the extra windings are to supply different voltage. Because you usually only get 208 when running single phase, which they say is generally not a problem, but I would disagree. I want 120/240. That extra series winding on each phase would make perfect sense if that were the case, but would not address the derating factor.

 

[grsthegreat]

208 is used all the time on 220/240 systems and is of no issue. A lot of apartments I worked on were supplied 3/0 to panels knowing everyone would have 208 volts. In the 100痴 of times I致e done this in over 35 years as an electrician I have had no issues. On average the only appliances using 208/240 in a residential panel are a/c, water heater, general heating and dryers. These are not effected by 208.

even if you rewire a 6 or 12 wire 3/0 to operate as single phase, you do get a loss in overall amperage available. Then again, I may be wrong Generator Phase Conversions: Electrical Conversion, Single Phase, Three Phase Power

It does get confusing.