High Mains Voltage

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raytaylor

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#171989 7-May-2015 21:24

Hi All
Had a UPS fail today - I think because when we switched it back on, the input voltage was 248.6 volts.
There was recently a transformer (or something) failed in the area and Unison did some work on it, but now I am getting customers reporting weird issues with their equipment from this particular area.

I hadnt really noticed a pattern until I saw that figure and thought its the highest I have ever seen - I thought the voltage should be around 230-240v

So perhaps Unison have a problem with whatever transformer or line they fixed recently and are supplying too much voltage?

Ray Taylor

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Dynamic

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#1300184 7-May-2015 21:46

The below suggests to me that up to 250v is acceptable:

http://www.legislation.govt.nz/regulation/public/1997/0060/latest/whole.html#DLM229459

If a transformer has been added/replaced in a semi-rural area, the output voltage may have been increased slightly so that supply to homes further down the line is boosted if they have had issues with under-voltage for a while due to voltage drop over the length of the wire.

I would like to think that equipment would cope with the 250v but perhaps the extra voltage is creating a little extra heat or just enough extra stress inside the equipment causing early failure. I'm assuming the power company will be unsympathetic. You may need to buy a voltage-reducing transformer for sensitive equipment if you find stuff keeps blowing up.

These guys were (commercial) neighbours of ours until recently. Karl the owner was a personable kinda guy and might have some advice: http://www.tsltransformers.co.nz/

In my experience, with UPS you get what you pay for. I see that time and time again.

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gregmcc

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#1300185 7-May-2015 21:47

just a little high, it looks like they haven't checked the voltage and set the tap correctly, ring your power company as there is a legal requirement to keep it within a specific voltage (from memory 230V +-5%)

Jase2985

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#1300202 7-May-2015 21:48

the UPS shouldnt fail with that little extra voltage, all my APC stuff is rated up to 280v

even the cheapie dynamix ones are rated to 290v

you should be seeing pretty much bang on 240v

Lias

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#1300220 7-May-2015 21:51

I was pretty sure that was within the allowable range so I just googled and found what I believe is the appropriate thing.
http://electricalconnection.com.au/when-voltage-varies/

Allowable voltage range is up to 253V

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gregmcc

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#1300221 7-May-2015 21:53

Dynamic: The below suggests to me that up to 250v is acceptable:

http://www.legislation.govt.nz/regulation/public/1997/0060/latest/whole.html#DLM229459

If a transformer has been added/replaced in a semi-rural area, the output voltage may have been increased slightly so that supply to homes further down the line is boosted if they have had issues with under-voltage for a while due to voltage drop over the length of the wire.

I would like to think that equipment would cope with the 250v but perhaps the extra voltage is creating a little extra heat or just enough extra stress inside the equipment causing early failure. I'm assuming the power company will be unsympathetic. You may need to buy a voltage-reducing transformer for sensitive equipment if you find stuff keeps blowing up.

These guys were (commercial) neighbours of ours until recently. Karl the owner was a personable kinda guy and might have some advice: http://www.tsltransformers.co.nz/

In my experience, with UPS you get what you pay for. I see that time and time again.

what you are look at is the definition of "low voltage" 200-250VAC, one of the standard supply voltages is 230V +-5%

Beccara

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#1300222 7-May-2015 21:53

AS60038 put's it at +10 or -6%, So 253v to 216v

edit:// Yes it's an AU standard but i'm 99% sure it's the same in NZ, cant be bothered digging transpower for info

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gregmcc

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#1300225 7-May-2015 22:00

Beccara: AS60038 put's it at +10 or -6%, So 253v to 216v

edit:// Yes it's an AU standard but i'm 99% sure it's the same in NZ, cant be bothered digging transpower for info

yes, but the NZ regulations trump the standards, 230V +- 5% according to the regs.

Bung

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#1300266 7-May-2015 22:31

The NZ Regs are +\-6% and Standards like 3000 quote both +10/-6% Aus limit and NZ limits. They aren't the same.

Aredwood

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#1300303 7-May-2015 23:41

Careful. There might be a failed neutral somewhere. If this happens the voltage could go up or down. Depending on how much load is on the phase you are connected to Vs the other 2 phases. Are the customers who are having problems all supplied from the same transformer?

raytaylor

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#1300311 8-May-2015 00:27

They are within the same rural area, about 3.5kms from each other.

So I am thinking it might not be the voltage then if its within the acceptable range.
The power was going on and off for 10 minutes at a time for about 2 days last month.
One of the residents said they had about 20 power cuts in that time so she got her husband to switch the mains off to their house at the fuseboard. They have not reported any issues other than needing to reboot their router which didnt come back on when he restored the power.

But four other houses have had fault tickets lodged since

1 & 2 were ethernet ports on their routers that would randomly stop connecting - the WAN was fine, but the LAN would stop working for hours at a time. I could remotely log into the routers but LAN was "unplugged"

3 was the wan port down, LAN port up - same status message, "unplugged"

4th house reported a UPS failure - went out and just switched it back on. Customer thought it felt "hot" but to be honest it was just slightly warm and i wasnt concerned.
When I saw the high voltage, suddenly it clicked that these 4 tickets in the area were all lodged in the week following that day of power outages.

The new model power supply spec sheets show a 90-260v AC input, but I will be going out to check one tomorrow as I am pretty sure the previous models stated 100-250v AC input.

Ray Taylor

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raytaylor

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#1301769 11-May-2015 10:15

Unison just called me back
216.2v to 243.8v

So they are sending out a technician after I confirm it with my multimeter.

Ray Taylor

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#1302642 12-May-2015 11:32

I had few months ago two professional UPS down. One failure was 100% not AC related but another one - not sure - did not check the voltage by then, should've done that.
As for the UPS - as been already advised - they are rated to different input voltages. Look up the menu - it could be adjustable in expensive UPS (I saw something in the APC manual)
My recent experience with mains supply - voltage dropped a bit and lights started flickering. The root cause was – contractor on the street used a digger and hit/shaked the distribution panel. That eventuated in loose contact, burned cable and increased resistance – hence voltage drop. Line tech (arrived as promised within 75 minutes) was able to find that in a few minutes and it was free.