Re: [CAD_CAM_EDM_DRO] 3 phase power supply

> Carlos Guillermo wrote:
> I don't know. And, when loads are turned off, etc. the output voltage could
> jump up. Also, when motors are slowing, energy is sent back to the power
> supply, so the voltage rises.

These peeks are dangerous. On a 4 kW Transformer I had a lot off trouble
going on and off line. This is what you can do about it:
Keep the old contactors as safety device and install electronical
solid state relays on each line. Depending on the size they aren't that
expensive.
When you switch on: first the contactors and 1/4 second later the SSR.
Switching off: first the SSR and then the contactor.
What the SSR do is, they start at zero volt and finish at zero amp.
This way you don't get any peeks and you won't have any sparks on the
contactor.
But the SSR won't last the rest of your life therefore is the contactor.
The SSR save you an awful lot of expensive repairs meanwhile.

Control devices are better to take of the power devices.
I separate them usually with UPS. Here in Latinamerika its a must
to prevent electronic damages

Good Luck
Sven Peter

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