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#145010 - 02/15/06 01:48 AM Non standard voltages
RODALCO Offline
Member

Registered: 12/08/05
Posts: 863
Loc: Titirangi, Akld, New Zealand
Today I had to install a datalogger on the network transformer at the tunnel drilling site for the Puhoi tunnel, north of Auckland on SHwy 1 to monitor for voltage dips on the 11 kV supply line which is at the end of a long rural line.

Also I had to load the fuses and do the 11 kV switching on the network switchgear as well as livening up the two mining transformers on site for the soak test, polarity, phase sequence and voltage checks.

The total consists of 4 transformers.

Network TF.3Ø 500 kVA. 11 kV / 240-415 Volts. 26.5 / 696 Amps.

Customers transformers.

Local site supply TF. 3Ø 750 kVA. 11 kV / 240-415 volts. 39.4 / 1042 Amps.

Machinery TF. 3Ø 600 kVA. 11 kV / 433 Volts.
31.5 / 800 Amps. ( 250 Volts P - N ) Dyn 11. impedance 4.41%.

Drill TF. 1000 kVA. 11 kV / 1050 Volts. 52.5 / 550 Amps. ( 606 Volts P - Screen ) Dyn11. impedance 3.92%.

The drill is driven from 3 x single core neutral screened cables.

Anyone else has some non standard voltages?
I can sent photo's of the TF. nameplates if anyone is interested.
_________________________
The product of rotation, excitation and flux produces electricty.

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#145011 - 02/15/06 02:31 AM Re: Non standard voltages
kiwi Offline
Member

Registered: 12/04/04
Posts: 347
Loc: christchurch new zealand
Thats a helluva big drill Rodalco ! Why the 1050 volt transformer ? Is that the drills working voltage ?

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#145012 - 02/15/06 02:50 AM Re: Non standard voltages
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Maybe this is an NZ thing?
I remember working at Pareora Freezing Works.
We had a 355VAC screw-feed Auger.
In one of the worst smelling places of the plant I wound, by hand a 23kW Cuprothal and fin element for the entrial cooker.
I had to sleep by myself that night after I got home, that was in the 500V Cooker Plant.
On the other side of the Plant there was a 35V ELV sensor system, for the well sensors.
Everything was really screwed away from us.
We had a rep from Rockwell Automation come out there, he ran away.
I think it was our 98.5V control Bus that scared him.
They train too many reps in uni's these days.

[This message has been edited by Trumpy (edited 02-15-2006).]
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#145013 - 02/15/06 02:54 AM Re: Non standard voltages
Trumpy Offline

Member

Registered: 07/05/02
Posts: 8540
Loc: SI,New Zealand
Oh and by the way we wound our own motors at Pareora.
_________________________
Let's face it, these days if you're not young, you're old - Red Green grin

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#145014 - 02/15/06 04:31 AM Re: Non standard voltages
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
The 250/433V spec was common in Britain before standardization at 240V. In fact there are still xfmrs around here so marked, just set a little lower on the taps.

Although 250 x SQRT(3) = 433V, it was also quite common for it to be referred to as 250/440V nominal.

No idea about the 1050V though. That's a strange one!

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#145015 - 02/15/06 07:29 AM Re: Non standard voltages
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: Stockholm, Sweden
I recently sold some equipment in a special version for a customer with a 525V system.

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#145016 - 02/15/06 09:01 AM Re: Non standard voltages
IanR Offline
Member

Registered: 12/06/04
Posts: 326
Loc: Palm Bay FL USA
While on the subject of nonstandard stuff, has anyone come across any DC mains still in operation?

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#145017 - 02/15/06 09:44 AM Re: Non standard voltages
Texas_Ranger Offline
Member

Registered: 12/17/01
Posts: 2343
Loc: Vienna, Austria
Hmmm... not so special, but a big technical school in Vienna (a real old one) ran on their own 127/220V transformer until the early 90s!
Think I already told you about the 150V receptacle at the rural substation.

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#145018 - 02/15/06 10:32 AM Re: Non standard voltages
RODALCO Offline
Member

Registered: 12/08/05
Posts: 863
Loc: Titirangi, Akld, New Zealand
The drill is brought in from Australia for the crew who does the actual drilling for the tunnel.
So are the special transformers, all been M.A.F. cleaned and certified.

 Quote:
Thats a helluva big drill Rodalco ! Why the 1050 volt transformer ? Is that the drills working voltage ?

That's correct kiwi. That drill is fed through 3 x single srceened cables at 1050 Volts ac.

I'm not sure if the 1050 Volts is a mining voltage, perhaps one of our Australian members knows, I'm actually back on this site again in the next couple of days and will ask the drilling crew if I get a chance.

Trumpy, I can see that for those odd voltages too you have to wind your own motors, they are not off the shelve items.

Texas Ranger, that was an interesting topic too, was in the 127 thread I remember.
_________________________
The product of rotation, excitation and flux produces electricty.

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#145019 - 02/17/06 06:13 AM Re: Non standard voltages
pauluk Offline
Member

Registered: 08/11/01
Posts: 7693
Loc: Norfolk, England
Just a thought, but in round figures 1050V would be the phase-to-phase voltage on a wye system with 600V phase-to-neutral -- 600 x SQRT(3) = 1039V. 600V is a standard voltage in a few places -- Canada for a start, so perhaps there's a link?

Re D.C. mains, I believe that some parts of India still use D.C.

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