Re: [CAD_CAM_EDM_DRO] Re: Fuses

In a message dated 2/6/2006 9:44:46 P.M. Eastern Standard Time,
elson@... writes:

Why do you feel fuses are needed?

Jon



Actually, Jon is correct. It is a BAD idea to put fuses between the
drive)s) and the motor. The drive(s) themselves should be protected by either
breakers or fuses but, the drive(s) usually have an over current protection built
in. Now, you might put a thermal overload between the drive(s) and the
motors and connect the overloads so that they disable the
drive(s) if they are tripped. This is the method used (when anything is
used between the motor and drive) by OEMs. If you don't have a method to
disable / stop the drive(s) when the connection between the drive(s) and motor is
severed, then you have a very good chance of burning out the drive(s)

My recommendation would be a thermal overload set just under the maximum
nameplate ampere rating on the motor and connect one of the auxiliary contacts
of the overload in series with the coil of a magnetic starter which would
supply the power for the drive(s). Depending on the type of thermal overload, the
auxiliary contact could be normally open or normally closed. You would
want the contact to be closed when the overload is in normal operating condition
and open when the overload is tripped.

I hope this helps some.

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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