ETD66SS wrote:

You still need an active and neutral so having them in one cable makes sense. It also explains the measured OD of the cable.
Each phase in a multiple phase system uses one of the other phases as a neutral. If you only have one phase you need a dedicated neutral.

TK88 your parents rural property is still low voltage (under 1000v). Also you can't apply Australian standards to a US installation.

ETD66SS wrote:

You still need an active and neutral so having them in one cable makes sense. It also explains the measured OD of the cable.
Each phase in a multiple phase system uses one of the other phases as a neutral. If you only have one phase you need a dedicated neutral.

TK88 your parents rural property is still low voltage (under 1000v). Also you can't apply Australian standards to a US installation.
 

But for 3PH, it would be a 3 conductor cable from the pole to the pad transformer?

nearly all power distribution is 3 phase no matter the voltage as 3 is naturally balanced the generators are three phase or multiples of 3. so it doesnt need a nuetral, each phase is120 deg apart.

but to get single phase you need a neutral wire that why in urban areas you will see 2 levels of power cabling on the poles the ones near the top are the high voltage 3 phase area distribution cables which then feed to the transformers which supply the lower level of 4 wires which you have 3 phases and a neutral. the neutral is referenced to earth and is the normal return path to the distribution step down transformer.

the reason they are running the high voltage to your own secondry transformer is to minimise power drop becuase of the distance and you will have a better quality feed. its ohms law every doubling of voltage halves the current for the same amount of power(wattage) it also keeps the cable size down as higher voltages run at less amps and thus less heat(heat increases resistance and thus power drop) for a given wattage. id say there was also a bit of future proofing as well if you ever decided to subdivide the land they wouldnt have to run new cables.

and yess they could use a 3 conductor cable to feed your sub transformer. depends how they choose to do it. if your system had it nuetral connection on your subtransformer and not the pole they could simply run a extra 2 cables, change the transformer and upgrade the switchboard. you should get some sort of "exchange" on the sub transformer as its still working and would have plenty of life left in it and they would install it elsewhere.

So the power company wants $50,000 to install 3 phase power, so that is not a financially viable option.

Any recommendations? Is a generator a better option than a rotary phase converter? Natural gas or diesel for the generator?

Old vintage Cat generator is course, my preference is diesel.

Regards

rax200 wrote:

Old vintage Cat generator is course, my preference is diesel.
 

I don't know much about CAT GenSets. If I wanted 480 3 PH 100A at say 20kW, how big of a unit am I looking at?

 

ETD66SS wrote:

rax200 wrote:

Old vintage Cat generator is course, my preference is diesel.
 
I don't know much about CAT GenSets. If I wanted 480 3 PH 100A at say 20kW, how big of a unit am I looking at?

Try to get in touch with ag-mike.   He has worked quite extensively on old Cat Gen systems. I haven't seen him on the board for a while so might try a PM. 
 

Here's an oldie but a goodie,
www.facebook.com/marketplace/item/232026...b9-afbb-fded14baf071
Another
www.facebook.com/marketplace/item/887051...b9-afbb-fded14baf071
Another
Marketplace - Diesel Generator 205KW Cat D334 No Rad '93 | Facebook

Those produce a heck of a lot of power.

while rotary converters work they are limited in what they can do and dont give good clean power the stepper motors in CNC equipment dont like it(the cousin had one and found it gave issues with his cnc machines). a genset however works better as it is a more correct waveform.

remember you need a genset 3 times the running power to start electric motors. for example a 3kw motor needs 9kw of power to start it. that's a rough rule.

there are generator calculators online to help you calculate the correct sized unit for your needs. work out what you want to run all at once and go from there. it pays to talk to someone experienced in supplying and setting up gensets so you dont over buy but also have a suitable unit with some headroom for expansion. no genset likes running at full power for long periods it shortens their lifespan. one thing to consider is you are probably only going to be using on machine at a time so pick the most power hungry one and add 10 percent to the final capacity required to get some headroom.

and there is a difference between standby and continuous(also known as prime power) rated units. some are only designed for standby use(temporary back up) and these units tend to use more fuel also there not designed to run for long periods. some units have a rating for both the continuous rating is always lower.

as for what engine to drive it diesel is the only choice. and buy a silenced unit. remember proper gensets are rated in KVA not kilowatts.