I am in the process of converting a 3 phase mill to run on a single phase supply. I have 2 x VSDs that will do this nicely, but I have been warned by the VSD supplier not to start the mill before the VSDs have time to initialise.

The mill has main contact relays, or circuit breakers that run on 24v AC via a 240v transformer, so what I was thinking, is to supply the VSDs with 240V for around 5 seconds before initialising the other 240v AC rail. What I am looking for is the simplest circuit that I can build.
Any suggestions would be greatly appreciated.
Cheers

Dave

 

Oh and I forgot to mention the amperage, most of the current for the mill motors is taken care of by the VSDs, but I think I will need around 3A at 240v to be on the safe side

Cheers again

Dave

 

here's a timer for 25$. It come with a base that mounts on a DIN rail, which your mill may already have

 

Thanks for the suggestion. This will be an ideal solution. The supplier that you linked to doesnt ship to AU where I am, but there arre plenty on ebay that will ship the same device. No point making one when the item is available off the shelf for such a small price.
Thanks again

Dave

 

Yay! A customer after my own heart.
I refuse to design anything that you can buy retail for less than the price of the parts it would take to build it.

 

What about a "Power On delay" with 555 Timer IC; with a driver transister and a BIG RELAY?

 

What about a "Power On delay" with 555 Timer IC; with a driver transister and a BIG RELAY?

For less than $25? For parts only, maybe, but not if your labor has any value. Cords, fuse and holder, power supply and PCB, switch, indicator light, enclosure. Drawings.

 

I agree, and I have already purchased 2 as suggested by strantor from ebay.
It's patently not worth designing, building, then fault finding a part, when you can buy it so cheaply. I like projects as much as the next person, but my project in this case is to do something on the mill, not spend 1/2 a day making a tiny bit of the machine.

Cheers

Dave