Re: [CAD_CAM_EDM_DRO] CNC mill DC motor field wiring

Hi, watch out if you get the field too low in voltage the armature can draw
huge quanities of current and do speed run-a-way. Its one way to get more
rpm but one has to watch armature current carefully. Playing with the field
voltage is a good way to get hurt and destroy equipment. be careful! cul
brian f.

----- Original Message -----
From: <skykotechnologies@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, December 13, 2002 11:24 AM
Subject: [CAD_CAM_EDM_DRO] CNC mill DC motor field wiring


> I finally got around to installing a 5HP 4 quadrant regenerative
> drive (from KB) on my shizuoka B3V mill. I didn't really know the
> specs on the motor, except that it is a 5HP DC motor, so I figured it
> was probably 180V armature, 200V field. The old broken spindle
> driver was labled 3.7KW DC motor speed control model 1-4064 by Sanyo
> Denki Co.
>
> Anyway, it works just fine, except I don't know if it is rotating as
> fast as it was designed. The field resistance is about 116 ohms, so
> I figured it had to be 200V. Would it hurt things to run it at
> 100V? I guess it is going to give reduced torque and double? the
> speed, which might be too much for the bearings.
>
> Any idea what the designed max rpm on this mill is? The old fanuc
> control panel had an analog spindle speed meter that has about
> 3500rpm and 740rpm as the max meter movement. That makes sense as
> the mill has a geared head with a 5 or 6 to 1 ratio (haven't actually
> bothered to measure the ratio yet). I would estimate the motor is
> spinning much slower than 3500...perhaps 1800 or so.
>
> I just got a 240VAC 9.5 amp autotransformer at an auction, so I
> guess I could easily build a variable field voltage generator with
> the addition of a small bridge rectifier....
>
> Thanks for any ideas or suggestions,
>
> Richard
>
>
>
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