DCS800 Speed Feedback

DCS800 driving 3HP motor. Although it has a tachometer, I can only get the motor to operate using EMF mode. Tachometer mode keeps faulting with '553', Tacho Polarity. Changed polarity without success, same fault.

Using the EMF mode, the displayed motor speed approx. 4 times the actual speed, (ex. actual 250 rpm, displayed 996 rpm). I've experimented with several related parameters without much change.

What am I missing? I'm sure it's something simple.

Thanks,

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jwolf Rank: 1621

Asked 2 months ago

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Hi,
Without some more details it is difficult to give you any reasonable advise.

Look in firmware manual, parameters 50 discuss about speed measurement.

From my experience I can advise first to reach accurate speed measuring using EMF.
That usually works with a good precision.
Try to start with factory default parameters and set the correct motor data - especially right motor data 99.04 (and other 99.x)

For the tacho input check S1 jumper on S DCS-CON-4 board - read in the hardware manual about the setting.
Fault F553 shows tacho's voltage is oposite than the EMF calculated speed direction

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by jwolf Rank: 1621 on 10/2/2018 1:02:53 PM | Like (0) | Report

Tried several changes without success. Tach from DC motor is 0-79 Vac. F553 is likely due to AC signal, so polarity will be incorrect with any wiring. Is EMF looking for DC ? If so, do I need to rectify to DC? I cannot see where this is done in the drive.

Thanks,

by kstoilov AKS expert

Rank: 8 on 10/2/2018 3:43:24 PM | Like (0) | Report

Hi,
I'm surprised you have AC tacho? How do you connect it?
For sure DCS800 will not accept AC tacho feedback, if you are trying to -X3 terminal. That is DC input.

EMF feedback - that is internal calculation of the speed from the inverter, you don't need external tacho or so on. Set parameter 50.03=0 and scale it with 50.01

by jwolf Rank: 1621 on 10/4/2018 1:05:21 PM | Like (0) | Report

Verified the tacho is an A/C unit (A/C generator). So I cannot use it. Tried sending signal through diode without success. After attempt with diode, the contactor wouldn't release. Had to remove power. Now it alarms with A137, speed not zero. 1.01 & 1.03 show 1 rpm. If I change 50.03 to 1 rpm, the alarm doesn't appear, but motor doesn't rotate. I see that A137 will be valid if drive is de-energized.

Is there a writable control word to correct this? Or memory cache?

Thanks again.

by jwolf Rank: 1621 on 10/4/2018 1:11:20 PM | Like (0) | Report

BTW, I tried Autotuning again, but it failed. Perhaps it best to reset to factory and begin again.

by kstoilov AKS expert

Rank: 8 on 10/5/2018 1:57:30 AM | Like (0) | Report

Hi,
As I explained above, try first with EMF feedback, don't connect tacho. For that set 50.03=0, that is feedback select, and not rpm ! Do you have a firmware manual where scaling is described?
Scaling is in 50.01, but other parameters have to be taken in consiferation - look the description in the manual.
The sasiest way, in case you are not sure, is - restore to factory default, set motor data and try to run. It should work with 50.03=0

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kstoilov

Rank: 8

Answered 2 months ago

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DCS800 Speed Feedback

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