Ungrounded Delta 480V/3-Phase/3-Wire System

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kwired

kwired

Electron manager
Location
NE Nebraska
Any wye connected "loads" to this system, and it is easy to overlook surge protection or ground fault monitoring, will create a "neutral point" on the system.

Even someone miswiring a wye wound motor or transformer primary, connecting the center point to ground, will create a neutral point on the system.
 
I

Ingenieur

Senior Member
Location
Earth
iwire said:
I do not think every ungrounded system had these, I think in the past they were optional.
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Still common in the surface facilities of underground mining
Not so much otherwise

I would say with a hi Z meter right at the xfmr lugs to the same point the voltages would be closely balanced
 
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my_mail_hub

Member
Location
Ohio
If there is no neutral point created in the factory, on the secondary side of the coil itselt, which will create a wild leg on the B or C phase, then it appears as if the intent of the manufacture was for you to use it to create your own corner grounded delta system. This may seem counter intuitive, but this how many old delta systems were done.

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kwired

kwired

Electron manager
Location
NE Nebraska
ptonsparky said:
I see he is a beginning apprentice. I was hoping he meant VOM.
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How many farmers do you work for that have a cheap $20 analog meter they use to troubleshoot irrigation equipment with, and once in a while have it on ohms setting and connect it across 480 volts? I still see several of these guys and they never learn from that mistake. I try to tell them they need a automatic volt/continuity tester that has no switch, but those cost too much:huh:

Seems to me, and considering you are lucky enough not to need medical care after the thing blows up in your hand, the thing will pay for itself after burning up 2 or 3 cheap meters.
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
kwired said:
How many farmers do you work for that have a cheap $20 analog meter they use to troubleshoot irrigation equipment with, and once in a while have it on ohms setting and connect it across 480 volts? I still see several of these guys and they never learn from that mistake. I try to tell them they need a automatic volt/continuity tester that has no switch, but those cost too much:huh:

Seems to me, and considering you are lucky enough not to need medical care after the thing blows up in your hand, the thing will pay for itself after burning up 2 or 3 cheap meters.
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I have one that was using the little neon glow testers. I chastised him multiple times. I finally bought him a Fluke TPro. I considered it a 'seed corn hat'.
 
R

retirede

Senior Member
Location
Illinois
kwired said:
How many farmers do you work for that have a cheap $20 analog meter they use to troubleshoot irrigation equipment with, and once in a while have it on ohms setting and connect it across 480 volts? I still see several of these guys and they never learn from that mistake. I try to tell them they need a automatic volt/continuity tester that has no switch, but those cost too much:huh:

Seems to me, and considering you are lucky enough not to need medical care after the thing blows up in your hand, the thing will pay for itself after burning up 2 or 3 cheap meters.
Click to expand...

You'd have to fry an awful lot of free-with-coupon Harbor Freight meters before it would pay to get a Fluke!


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