Suddested that I post over here. Need US source for this switch - no maker identified on the switch itself....

Thanks,
Grov

Service call this morning - the lathe won't start - trips breaker.... Low voltage 3 phase.
Lathe is a TOS (Chech Republic) - no real US dealer - they bought it used several years ago. It appears that it is set up for a manual changeover - operator says "We start it with this switch pointing toward the Y, and then flip it to the Delta (symbol) With pride, he says "It's a soft start.", and then hit the Start/Stop buttons - breaker trips.

One section of the the 4 section "drum switch" seems to be bad - found burned lead and the switch doesn't "feel right" -

If that's right, it gets 3 phase Y for start, and only 2 phase delta for run.

Thinking about replacing it with a US switch, but need the configuration - Chech diagrams not a lot of help.....Euro conventions for symbols and Chech notes.... It seems to be a 4 section switch, with each section having 2 pairs of contacts.

Anyone familiar with maual Y-Delta starting? Customer is chasing a new part thru the used equipment dealer.....but I'm doubtful.......

Thanks for your help / suggestions.

The older manual star delta start switches had a rotary knob.
position 0 off.
position star start in star.
position delta run in delta.

On European equipment the three supply phases are marked as R, S, T or L1, L2, L3
I take it that the motor has a 6 terminal block and is probably rated at 220/380 Volts ?

In star position:
The connections are,
R, S, T are connected to U, V, W respectively while X, Y, and Z are linked with each other.

In delta position:
The connections are,
R connected to U and Z.
S connected to V and X.
T connected to W and Y.

I can post a schema from a trade book if you wish which will show you the actual contact positions.

edited for typo's

[This message has been edited by RODALCO (edited 07-28-2006).]

[This message has been edited by RODALCO (edited 07-28-2006).]

See this post in the US section too.

The manual rotary switch can easily be replaced with two 3 phase (ideally electrically interlocking) contactors and a timing mechanism (2 to 3 secs).

Thanks for the reply. I have done some work with electronic soft start - like Benshaw, and understand the theory behind Y-Delta start. Wish I could read Chech to understand teh notes on the one diagram I have.....

I'd love to see your schematic if it's not too much trouble.

Customer seems a little nervous about "re-engineering" - would prefer a replacement switch, but I may have to give it a go....

Just took the photo's after midnight but keen to help out.

Hope they post ok via flickr



Rotary switch



Contactors and timer

{ Images enhanced & copied to ECN server - Paul }


[This message has been edited by pauluk (edited 07-29-2006).]

Is there a misprint in the first diagram?

It looks as though the bottom connection on the switch should be labeled Y instead of U.

No pauluk.
Actually well spotted.
This is one of my old Dutch trade books and the dutch IJ are the letters I and J combined. nearly pronounced as the English Y.

The EnglishY is pronounced as the "egreck" and is the 25 th letter of the Dutch alphabet.

Perhaps the "double dutch" quote comes from some of our combined letters like UI EU IJ who knows

Many thanks for the pics! I hope to be back at the job on Mnoday - I'll keep you posted.

Brov