Re: [CAD_CAM_EDM_DRO] Please help Permanent Magnet Field Servo Motor???????????

The existing SCR Servo controller is from GETTYS and
the type is 11-1010-5H, Due to it's slow response I
want to change it with the Servo Dynamics 2550BR drive
(25 Amp Cont, and 50 Amps Peak)
I don't have the data of SCR controller, so I don't
know which pot do what, does anyone have come across
these Drives?

Regards

Ubaidullah Babar

--- Jon Elson <elson@...> wrote:

> Babar wrote:
>
> >Two wires are the AC input of Drive 250 VAC, The
> other
> >two wires are shorted at the motor , the other end
> of
> >the motor is connected to the Ground.
> >The response of this drive is very slow and it is
> >causing troble in the form of large following
> error,
> >any suggestion to improve the Drive's response?
> >
> Well, an SCR drive is limited by the line frequency.
> A 3-phase
> SCR drive running on 50-Hz power can't get more than
> 300 pulses
> to the motor per second. That should still be
> adequate for a heavy
> machine, probably giving a closed-loop response out
> to 75 Hz or so.
> What is the current limit set for on the SCR drive?
>
> But, if it is driven by an aged CNC control, that
> may be what is
> limiting performance. I used an Allen-Bradley 7320
> control, and
> its 100 Hz servo update cycle required the system
> response to
> be awfully sluggish. Updating it with a PC-based
> CNC control
> improved the following error as well as the dynamic
> response
> considerably.
>
> > what
> >if I connect the two wires that are short at the
> motor
> >to the two ends of motor instead of connecting the
> >motor's one end to the ground?
> >
> >
> >
> That isn't going to improve performance. You need
> to find
> out what the extra wires are connected to in the
> motor.
>
> >Why the line reactors are needed with servo
> dynamics
> >drive? I understand that these are simple inductors
> >(am I right?)What is the selection criteria for
> these
> >reactors?
> >
> >
> Check the drive manufacturer's data sheets for the
> minimum
> motor inductance. If the motor's inductance is less
> than that, you
> need to add inductance to bring it above the
> minimum. Just an
> example : If the drive requires a minimum of 10
> milliHenries,
> and the motor is 7 milliHenry, then add a 3 mH
> inductor in
> series with one motor lead, or one 1.5 mH in series
> with EACH
> motor lead. Either way, you get a total inductance
> of about 10
> mH, as the manufacturer requires. They are ordinary
> inductors,
> but they must have a current rating equal to your
> peak motor
> current, and either have thin steel laminations or
> ferrite cores
> to reduce heating from the PWM frequency.
>
> Jon
>
>
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