Source
r/Generator•
wooparse

3 phase problem

Hi everyone,

Hopefully this is allowed. We're without power in Australia due to storms and we have a 3 phase 70kw generator installed to power the house in such events.

It was running for 24hrs without issue but then it had an undervolt alarm and shutdown. Now that may have been due a fuel shortage to be honest. Since refilling though, the generator starts fine but after between 10 and 15 minutes there is a Gens Overcur Alarm and it shuts down.

In the event viewer it appears the it's the third phase that is the problem with it reading Amp 5 3 23

The house has no 3 phase equipment in it and a shed with a 3 phase outlet isn't connected.

Does anyone have any idea on troubleshooting steps? And yes getting a maintenance team out would be great except that waitlist is longer than the mains service restoration.

Woop

Posted Dec 29, 2023, 9:55 PM UTC

211
Acrobatic_Jaguar_623•

They run 3 phase to houses in Australia? How big is your house that you need a 70kw gen? What's the output voltage in Australia on 3 phase, 240/415v?

2
nunuvyer•

Australia is a little strange in that the "official" voltage per the gov. standard was lowered to 230/400 maybe 20 years ago, +/-5%. Since 240/415 is within 5% of 230, the utilities responded by doing nothing and so the actual voltage at the wall is 240 as it always was.

Large houses in Australia do sometime get 3 phase service. The reason is that the standard single phase service is only 63 amps. IDK why their single phase service is so small or why they just don't make it bigger instead of bringing in 3 phase, IDK but that's how they do it down under.

2
Jim-Jones•

That sounds like the normal Kiwi setup. 230 volts and 60 amps.

2
nunuvyer•

Just as CA standards are usually similar to US electrical standards, NZ stuff tends to be similar to OZ. Generally your stuff usually resembles the nearest bigger country because of manufacturing economics. NZ and Oz also both use a plug that resembles US plugs except that the blades are turned 45 degrees (and the ground prong is another flat blade)

2
Jim-Jones•

Actually the Kiwi/Oz outlet is a US 240 volt standard. It's just rarely used in North America. We copied some bits from the UK and some from the US. I understand that New Zealand now has a 15 amp outlet that is similar but not the same. "More power!" to quote Tim the Toolman Taylor.

2
watchurtongue•

Addressing the need for optimal electrical circuit performance, it is recommended to consider rebalancing the phases, as the current distribution currently lacks balance. To achieve this, consider reducing the load on phase three while simultaneously activating electrical components on phases one and two. It is crucial to ensure that the current values across the phases remain relatively uniform, promoting a balanced and efficient electrical system.

2
wooparseOP•

Would there be an obvious reason why it was balanced several days ago but then running the same appliances it has caused the third phase to be the main one used? I assume each phase runs a separate circuit so without physically changing them, there should be no reason for the unbalanced phases?

1
Jim-Jones•

I'd try and find someone, even a retired sparky, to come and have a look at this for you. You need somebody with meters and the knowledge to figure out what's going wrong. This is a bad situation to try and learn in. Do they have job listings on Gumtree?

2
nunuvyer•

Are your panels labeled as to the phases? Separate panels for each phase? Figure out what is on phase 3 and throw the high value breakers on phase 3 and see if that rebalances the system. Maybe there is some big draw on phase 3 (a demand type hot water heater or something) that is overloading that phase. It's better to lose just that device than to not have any power at all.

2
wooparseOP•

Hi everyone thanks for the replies.

I think we figured out the culprit. Normally the ducted AC can run fine on the generator but this time it couldn't and it was the item throwing the alarm. This happened once the compressor kicked in on cooling, not on fan only.

We theorised that there might have been a brown out originally that has done something along the lines to cause the AC to pull all 28amps of 3phase power from just L3.

Mains are now back and I expected an error to come up when trying to run the compressor or a breaker to trip however it hasn't, the cooling is working.

So long story short, the generator ended up unbalanced for a reason we don't know yet.

Thanks again everyone.

Woop

1