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Grounding delta delta transformers on CNC machines

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Joethemechanic

Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
I'm really surprised. that the power supply for the electronics in these expensive machine tools isn't better

And why are machines built for the US market not 480? I have 240 3 phase because it was here when I bought the place. But if I was starting from scratch it would be a pad mount with 480/277
 
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W

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Joethemechanic said:
I'm really surprised. that the power supply for the electronics in these expensive machine tools isn't better

And why are machines built for the US market not 480? I have 240 3 phase because it was here when I bought the place. But if I was starting from scratch it would be a pad mount with 480/277
Click to expand...

1) It is very common for machines to be designed with the expectation of a grounded wye supply. This lets things like TVS circuitry and input filtering be designed with tighter clamping ranges. It also makes the balance of the DC rail relative to ground better. I wouldn't call a power supply designed for a balanced grounded wye 'bad' if it is unreliable on an ungrounded delta.

2) Agreed. I don't see a good reason to design for lower voltage. IGBTs and inverters for 480V are common off the shelf items.

-Jon
 
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