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How does current reduction work on P7000 Tools?

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I am using P7000 Tools to setup a 3rd party stepper +  NI motion controllers. I have everything working correctly, except that the motor gets hot when idle (but not killed). I know that this can be aleviated by enabling "Current Reduction" in P7000 Tools, under the "Advanced" tab. However, I'm interested to know whats actually happening and what the time and % fields control. I currently have my system to enable (on), ms (100), and % (90).

 

1.) I undestand that Current Reduction reduces the holding current when the motor is idle. Does this mean that my motor will support less static weight when enabled?

2.) Does the percentage field mean "reduce to" or "reduce by"? So with current reduction set to "90%", am I a reducing TO 90%, or BY 90%?

3.) What does the time field control?

4.) How does Current Reduction affect acceleration? If I'm not holding at 90%, does the motor go immediatly from 90% to 100% for acceleration?

 

thanks,

jason

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Accepted by topic author tir38
08-27-2015 04:09 PM

tir38

 

1.Yes.

2/3, see below, from the manual:

 

Current Reduction

Current reduction reduces drive and motor heating by invoking standby current reduction. When

enabled, current reduction cuts motor current to 75 percent of its commanded value 100 ms after receipt

of the last step pulse. You can adjust the reduction proportion and delay to other values using the P7000

Tools configuration software.

When current reduction is enabled, the motor holding torque is reduced. Do not enable it for applications

that require full holding torque when the motor is stationary.

Table 9 lists the current reduction DIP switch settings.

Note

Current reduction is enabled when switch S2–10 is OFF.

 

4. I am not certain, but typically on other stepper drives this does not affect acceleration.

 

Link to manual:

 

http://www.ni.com/pdf/manuals/372324c.pdf

 

-AK2DM

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