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Discussion Starter · #1 ·
Customer needs a large automated saw connected. 460V 3ph. Phase to Phase voltages are averaging 524V. This out of the tolerence per manfacture of the machine so I'm needing to install a transforemer to correct the voltage. Also the manufacturer recommends this be a WYE connectrion on the secondary due to all the VFDs in the machine throwing faults for the incoming power. I cant wrap my head around the bonding and grounding of this transformer for some reason. I looked at an existing transformer for general purpose lighting and oulets. On the primary side the there is a "grounding" conductor it goes to the case of the xfmer and then feeds throught to the panel on the secondary side. XO has the neutral conductor and a grounding electrode conductor only that goes to a ground rod beside the xfmer.

Thank you in advance.


Electrical wiring Electricity Wood Circuit component Electrical supply
 

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Power distribution and controls
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We used Delta-WYE for the distribution transformers at the University. Delta primary 12.47kv
Wye secondary for user voltages, 120-208 or 277-480v. Someone said this configuration kept a good portation of the anomolies on the primary side, rather than having them feed through to the secondary.
 

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Retired IBEW inside wireman
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On the primary side, what is the voltage to ground on each phase? If one is zero and the other two are 480 or 525 then yes it is a corner grounded system. If all are zero to gnd, then probably a floating delta. primary.
 

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Discussion Starter · #11 ·
On the primary side, what is the voltage to ground on each phase? If one is zero and the other two are 480 or 525 then yes it is a corner grounded system. If all are zero to gnd, then probably a floating delta. primary.
[/QU

Corner Grounded. A to Earth = 524. B to Earth = 0, C to Earth = 524
 

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Bilge Rat
motors and controls.........
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If there are VFDs involved, I would highly recommend installing a 480∆ - 277/480Y transformer.

The primary side doesn't care about voltage to ground, in your case it'll be 3Ø 3 wire. One of the phases is already grounded, if you can find where the phase and ground are bonded together, you'll need to pull a ground wire from there with the 3 phases. The fact that it's a corner grounded ∆ doesn't matter.

The secondary side is a separately derived system. There's no electrical connection between the 2 sides so you'll need to bond the 277 neutral to ground.

When you're done, the incoming primary ground, the secondary ground, the secondary neutral, the transformer frame, and if applicable, the building steel and the ground rod (or whatever the grounding electrode is), should all be connected together.

If you bond the 277 neutral to ground at the transformer, don't bond it to ground anywhere else.
 

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Ready Mix concrete plant electrician
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They're not going to do anything, we are the only ones complaining. 🤷‍♂️
If they won’t listen, tell them the next call when you hang up with them is going to be to the public utilities at the state.
High voltage is bound to be causing other problems, low PF, excessive heating of motors and subsequent shortened life, excessive start torque on motor driven equipment, and the list goes on.
 

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Buy this type of 480/277-480 Delta Wye Transformer in the size you need for the saw:

Check out this wiring diagram:

You should be able to adjust the taps to get exactly what you need.
 

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The highest taps on those is 504V, that will not fix his 524V service problem. For that he needs to call the utility service commission in his state, if the utility refuses to fix the problem.
 

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Hackenschmidt
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I would complain to the power company, 524 vac is too high, way too high. They need to adjust the taps at the substation.
The highest taps on those is 504V, that will not fix his 524V service problem. For that he needs to call the utility service commission in his state, if the utility refuses to fix the problem.
They're not going to do anything, we are the only ones complaining. 🤷‍♂️
In my experience this is one of the things they don't try to wiggle out of, even if it's just one small customer. It's too easy for the customer to test and show that they're outside of their public utility requirements. If they don't respond and you call the utility commission, they will still have to fix it, and deal with all the utility commission red tape as well.
 
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