Please help - X2 mill reversing DC motor mystery

I decided to add simple reversing switch. I have seen similar mods on the net,
so I thought that it is going to be an hour job. At most. Apparently I was wrong.

Motor:
Type: 95D-1
350W DC Motor 230V
Class E Reverse

I have added switch DPDT - FWD/REV. When switch is in FWD position ir works
without any problem as before. When it is in REV position - it does not work.
There is no any indication on the motor that power is applied - no sound, no
movement. When trying to move spindle by hand it just turns freely without
any resistance.

How did I tested it so far:

1. Connected multimeter in parallel to the motor. Strange thing here - in the FWD
mode, when power is connected (but switch on the pot is in the OFF position) -
it immediately indicates +90V. Also, when you grab the spindle you can feel that
it gives more resistance in turning the motor in one direction. When turn the pot
to the right, passed the switch - voltage gradually changes from 90V to -90V and
RPM increases as expected.

When power is applied when the switch is in the REV mode - multimeter shows
+30V. When turning pot to the right voltage gradually changes from +30V to +204V
and motor does not work at all

2. I have disconnected motor from the controller, and connected to 12V DC
power supply. There was no any reaction from motor in both FWD and REV
modes.

3. I have connected motor to 4A bridge rectifier - again, no any reaction in both
FWD and REV switch positions.

4. When connected back to the controller - it works just fine, but in FWD direction
only.

Why it does not work as expected ? Are there any other tests possible to find
out what causes this problem ?

Any helpful answers will be much appeciated.

Why would expect movement from a DC motor requiring 90-130v on a 12v power supply?

Can you take a photo of the wiring on the DPDT switch and how it goes to the motor? Is the motor connected to center contacts of the DPDT? The way I have seen other motors reverse is by wiring an X on the 4 outer contacts, with power coming in from 1 sides contacts (of those 4). The X reverses the polarity.

Hello;

Are the brushes on the motor exactly at 180 degrees? If they are offset it might be a uni-directional motor, sometimes employed on the treadmills, etc.

kreutz

Quote:

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Originally Posted by Fastest1

Why would expect movement from a DC motor requiring 90-130v on a 12v power supply?

---

Any decent 90V DC will WILL spin on 12V. In fact, it should spin on much less than 12V. For any brush DC motor, voltage controls RPM, current controls torque. Reduced voltage simply means reduced RPM, down to the point where there is not sufficient torque to over-come the internal friction of the motor.

His switch IS wired incorrectly, but since he hasn't provided any information on how he wired it, not much anyone here can do to help.....

Regards,
Ray L.

The reversing switch wired on the KB versions of drive might help, see last page.
http://www.kbelectronics.com/manuals/kbmd_240d.pdf
A relay would be wired exactly as the switch and have a centre off position, this ensures you do not go directly from FWD to REV in one motion, notice the switch also connects the drive disable I1 & I2 so that the drive is reset and the accel takes place rather than going from full rpm in one direction to the other.
I would also expect a 240v motor to move on 12vdc, off load.
Al.

Please see attached photo of the switch wiring.

Attachment 261134

@ Fastest1 - I have tested treadmill DC motor with 12V and 200V (after rectifier) - it was spinning just fine.

@ kreutz - yes it seems to be regular 180 deg arrangement.

@ SCzEngrgGroup - I am curious to learn how did you come to conclusion that switch is wired incorrectly

@ Al_The_Man - thank you for the link. It seems that I have wired the switch just the same way, less the brake resistor.

What makes me really lost is the fact that motor runs just fine from the controller,
but refuse to spin in any direction when powered _directly_ either from 12V or from
200 volt DC. Did anyone experienced anything similar ?

Second, why in the world I can see on the voltmeter that controller supplies 90V at
the lowest speed when motor start spinning, and then when turning pot clockwise
increasing RPM voltage goes from 90V to 0V (at about 50% speed), and then goes
to -90V at the maximum speed ?

First, go back to basics. Hard-wire the motor to the controller, and confirm that it operates properly, including speed control. Then, reverse only the two motor connections, and confirm that it operates properly in the reverse direction, including speed control. Once done, you have confirmed both motor and controller are working properly, and the switch should be doing precisely what you did by reversing the motor connections in the above test. If it doesn't, then the problem HAS to be the switch itself, or the switch wiring.

As for the voltage readings, unless you're using an analog voltmeter, you're not likely to get meaningful readings across the motor. The controller is driving the motor with a PWM signal, which is, from the meters point of view, neither AC nor DC, but has characteristics of both that will confuse the electronics in the meter. Once you've run the above tests, and confirmed the motor and controller are both working properly, voltage readings are really not necessary, or helpful, anyway. Resistance readings can confirm that the wiring, and switch, work as expected.

Regards,
Ray L.

I noticed on another forum a member with the same motor declared it ran OK in both directions, he also mentioned a uni-direction on the motor plate?
Out of interest, if you have a meter, measure the resistance on the motor leads on both directions, use the Ohm scale, not the Diode test scale.
Al.

Judging from your picture of the switch. It appears to me your motor and controller connections are reversed. The motor should be tied to the center taps of the switch in the examples I have seen. It could work exactly the same on your switch as it is.

I second AL_The_Man test. Did you check/clean the motor brushes?