Re: [CAD_CAM_EDM_DRO] Re: Running a Bridgeport Interact 1 Mk1 on single phase 240v

dgsutton2000 wrote:

>If the transformer is connected to 2 420v phases then at any one
>time in the 50hz cycle are you saying the potential differance and
>wave form is the same as between a netural and 240v single phase? If
>so this answers a vast number of questions for me!
>
>

NO! The input to the transformer is 420 V, and there would be no
neutral involved.
Now, on a 420 V 3-phase system with a neutral, the voltage between any line
and the neutral is 240 V. If you take 420 and divide by the square root of
3, you get 242 V. So, in this case you need a transformer with a turns
ratio
of 1.732 : 1 We don't see transformers like this too often, but if your
distribution
system is built this way, it may be common. We have 2:1 transformers
all over the
place. We do use a similar system in office buildings, where you have 3
lines
with 120 V to N, and that gives 208 V L to L. But, we also have 240 and
480 V
3-phase systems, that are much more common in other than office settings.
(We have ALL 3 in our building at work!)

>If the above is correcy I am out to get a step-down transformer to
>get 3KVA reverse it and get back up to 420, Jon you guessed right
>the 420 3-phase mains is standard here in UK thats a great solution.
>
>

Well, if you can find the 1.732:1 transformer, you should be fine. A
2:1 would
give you 480 V, which might be too much for the system, unless it has taps
for that.

Jon