# Curtis 1238 AC controller setup



## SyCo (Feb 15, 2008)

Some additional information... since I don't have all the answers, I've tried different settings after having some more specs for my motor (no. of pole).

The motor is revving a lot easier with new settings:
Encoder steps: 64
Pole: 6 (previously set to 4 before I've some help from *major*)

I'm also in contact with someone at Curtis Instruments and it seems that with my specific handheld programmer I can "learn" my motor charateristics... I'll let you know the results 

Anyone know if I use the wrong settings if it can damage something ? (please note that all tests are conducted with car jacked and in neutral)


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## SyCo (Feb 15, 2008)

*UPDATE*

I've received the procedure from Curtis and ran the characterization test. I was lucky to have the "OEM" handheld programmer because it was mandatory to perform the test.

Now my motor is a lot more responsive. The "slip gain" has now been set to 0.78 using the automated procedure and it looks it is a good setting because if I play with it by myself the response change quickly.


Now another question ...
Using my handheld programmer I can monitor the amp at the controller. The manual states: "_Current (RMS) of the controller, taking all three phases into account._" I also use a Fluke 1000 DC amp-meter on my positive cable from the batteries.

Can someone explain to me why the reading is different ? The controller says ~200A and the Fluke says ~50A ?!

Which one should I trust to read my amps ??


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## major (Apr 4, 2008)

SyCo;148747Using my handheld programmer I can monitor the amp at the controller. The manual states: "[I said:


> Current (RMS) of the controller, taking all three phases into account.[/i]" I also use a Fluke 1000 DC amp-meter on my positive cable from the batteries.
> 
> Can someone explain to me why the reading is different ? The controller says ~200A and the Fluke says ~50A ?!


Hy Sy,

The programmer is telling you the AC current (RMS), or phase current. The Fluke is clamped on the battery lead so reads DC current. The difference between motor current (AC) and battery current (DC).

I assume you are doing this at no load on the motor, maybe wheels up or in neutral. Induction motors are terrible for power factor at no load. So a big part of the AC current is reactive.

For an induction motor, the no load current is basically the magnetizing current. 200 amps (AC) does not sound out of line for a motor at that voltage. 50 amps (DC) sounds high if you're working from a 48 volt battery.

Regards,

major


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## SyCo (Feb 15, 2008)

major said:


> Hy Sy,
> ... 50 amps (DC) sounds high if you're working from a 48 volt battery.
> 
> Regards,
> ...


Yes, wheels up in neutral... ok now I understand between AC vs DC. I will double check tonigh my amp AC and DC and the corresponding RPMs.

I think my reading maybe off because it was by memory


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## yarross (Jan 7, 2009)

major said:


> For an induction motor, the no load current is basically the magnetizing current. 200 amps (AC) does not sound out of line for a motor at that voltage. 50 amps (DC) sounds high if you're working from a 48 volt battery.


Hmmm. 50A @ 48V makes 2.4kW. Looks excessively high for no-load conditions.
SyCo, is this a RMS value?


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## SyCo (Feb 15, 2008)

yarross said:


> Hmmm. 50A @ 48V makes 2.4kW. Looks excessively high for no-load conditions.
> SyCo, is this a RMS value?


Well I'm using a Fluke meter clipped around my positive cable @ 48V and the value appears on the display. Don't know if it's RMS or not. About the load I did some tests sometimes in gear sometimes not. I think I remember less than 10A DC in neutral.


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## billbobagns (Nov 28, 2009)

A note about current, three phase, AC, DC. Major is completely correct to point the difference between AC three phase, or Phase current and "DC" current. In a drive like this, I don't happen to know the relationship, but clearly their is a significant difference. Also, the induction of the motor can cause considerably high phase current with a very low power factor. This could cause a great difference between the two.

Also, most clip-around DC amp meters are (I believe) "Hall-effect" sensors, require you to "zero" before use, and are somewhat unreliable at times.


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