Re: [CAD_CAM_EDM_DRO] servo E-stop circuit

In a message dated 7/15/2004 9:52:29 AM Eastern Standard Time,
snaggletto@... writes:
There are 2 NC (normally closed) 15A 'contacts' in the upper section
of the drawing that switch the braking resistor in during E-stop.
Are these more like relays, or contactors, circuit breakers or what?
I've done some looking at places like automationdirect.com, and they
seem to have them as 'inductive' motor starters (some are for
resistive loads).
In your OEM industrial machines, the OEM usually installs contactors, not
relays, to handle the switching of the braking resistor. This is for the same
reason as someone else mentioned, the actual spacing between the contacts
themselves. Since you are likely switching DC current/voltage, then arcing across
these contacts is more severe than with AC. Also, there can be large surges of
current when the brake resistor is switched on/off.

You might want to check out distributors for Telemecanique (Grainger is one)
or Square D ( same company as Telemecanique, Schnieder). They have reasonably
priced and very reliable components which are used in many of the European
machines.

Randy Abernathy
4626 Old Stilesboro Road
Acworth, GA 30101
Ph / Fax: 770-974-5295
E-mail: cnc002@...

I furnish technical support, repair, and other related services for your
industrial woodworking machinery. My background as Senior Service Engineer for the
SCMI Group for nearly fifteen years with factory training, combines with my
extensive background in electronics, mechanics, pneumatics, electrical and CNC
machinery to offer you needed support for your machinery.


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