Powering a 24V DC motor

Plc_User · May 19, 2008

I have a 24V DC motor from Dunker, a type comparable with the 'GR 80x40' but older, with has a nomnial current of about 6A (but starting current can be almost tenfold as seen on the info sheet).
The motor used to be powered by an old electronic print, which I don't want to use anymore. A discrete level of 24V in one or the other direction is enough for me (speed variation is not necessary). One solution would be a separate 24V DC power supply for the motor (6,5 A) and a solid state (for frequent switching).
But I was thinking isn't there a simple DC-drive powered by 230V and that has an output of 24V that can power this Dunker Dc-motor.
Please share me your opinion or experience, thanks.

http://www.dunkermotoren.de/default.asp?id=9&mid=15&lang=1

OkiePC · May 19, 2008

I have been in that position before and had no luck finding a DC drive with less than a 90vdc armature voltage with 115VAC input...

Mine was for a linear actuator/drive system with a failed drive and no spare.

I ended up temporarily using a generic one with 90vdc output with the max speed and current set as close as possible to get max rated motor RPM, but the signal driving the motor was PWM 90vdc with an average voltage much closer to 24volts.

It worked okay for a few weeks until the replacement OEM drive came in. I don't recall mfg, but we had a lot of trouble with their drives, and they kept updating them, making the old ones obsolete.

I know you could find a DC drive with DC input, as there were many of them around even then. If you did that plus a battery (or two) and a charger to go with it, it might work for your application.

Wish I had more to offer.

Paul

ndzied1 · May 19, 2008

What you need is a 24V DC power supply that does not "fold back" it's current when the motor draws it's startup current but slopes down it's voltage. Then you just need relays to switch the polarity of the DC signal to the motor for reversal.

One such power supply is the Qunit line from Phoenix Contact.
http://eshop.phoenixcontact.com/phoenix/treeViewClick.do?UID=591736971&parentUID=205579&reloadFrame=true

Here is a short description:

Power supply units with U/I characteristic and power boost are electronically protected
against overload and short circuit. At nominal voltage the maximum output current of these
devices is up to two times the nominal current, depending on the type and amblent.
temperature.
Overloading individual power supply units is thus permitted up to 100%. In the event of
heavier loads the working point uses the U/I curve shown in Figure 3-28. In the event of a
short circuit the output current of up to two times the nominal current is still available while
the output voltage is reduced.
The power reserve ensures that highly capacitive loads and loads with DC/DC converters
in the input circuit are supplied at any time without problems.
In the event of a load short circuit, the high short circuit current ensures reliable fuse
blowing in the secondary circuit in order to keep the selectivity.
These properties make power supply units with U/I characteristic and power boost
optimally suitable for use in universal industrial applications.

We have successfully used the Quint power supplies with Dunkermotoren Motors on magnetic conveyor applications unloading parts from a stamping press at one of our customers.

Also note that the Qunit 5A power supply can actually supply 7.5A continuously so long as the amblent stays below 40 deg C.

The new models called Qunit SFB might be lower cost than the original Quint series and supply 6X reated current for 12 msec

<Note/disclaimer: I work for a distributor that sells Phoenix Contact and Dunkermotoren products>

Electrically_Bound · May 20, 2008

It is tough to find what you are looking for among the more common names in drive manufactures, but you might want to look at some of the ads in Nuts and Volts. Small, compact DC motor drives are available from a lot of manufacturers as these are important items in the hobbyist robotics market. These drives do require a dc input, but a simply power supply could be installed to get your desired ac input down to 24VDC.

tragically1969 · May 20, 2008

Is there anything here that meets your spec:

http://www.sprint-electric.com/prodsumm.html

shooter · May 21, 2008

use a normal power supply for 24 volts and your amps needed and just switch on the supply.
if needed better control use a lab supply with a potmeter or analog input for the voltage.

ndzied1 · May 21, 2008

shooter said:
use a normal power supply for 24 volts and your amps needed and just switch on the supply.
if needed better control use a lab supply with a potmeter or analog input for the voltage.

Shooter, The motor inrush current can fault out a lower quality power supply. You simply cannot use just any power supply. It has to have the ability to keep from "folding back" when it reaches it's current limit. Many power supplies do this by actually dropping out for a short period instead of riding out the storm. They can never get the motor started.

Power supplies Like the Phoenix Quint I mentioned before and some higher quality Siemens / PULS and Sola supplies keep pumping current (while reducing voltage to protect themselves) to get through the startup of the motor startup period.

Powering a 24V DC motor

Plc_User

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OkiePC

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ndzied1

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Electrically_Bound

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tragically1969

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shooter

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ndzied1

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