Controlling Variable Frequency Drive Speed

A

Thread Starter

AhmadH

Hi,

Need your help!

Im trying to control a motor speed using Yaskawa A1000 series drive. We are giving start/stop signal through PLC and controlling speed against analogue input signal of 4-20mA. We need to run motor at 15 rpm. At current setting motor works fine as per analogue signal 0 rpm at 4mA and 1200rpm at 20mA but we need to control at 0~15rpm. I'm unable to find the parameter to control it as.
VFD manual no is TOEP C710616 41E.

Rgds,
AhmadH
 
G

Gerald_Beaudoin

At that speed, you will definitely need external cooling, as the internal cooling will be non existant. Trying to run a motor at 1% of its rated speed and expect good control?....not a good idea. Have been down that road many times because of poor engineering and sizing errors.
 
>At that speed, you will definitely need external cooling,
>as the internal cooling will be non existant. Trying to run
>a motor at 1% of its rated speed and expect good
>control?....not a good idea. Have been down that road many
>times because of poor engineering and sizing errors.

Is this a problem with just this brand of drive (YASKAWA) or a problem of any drive. Is the drive not supposed to be able to send speed all the way down to 0 rpm?
 
G

Gerald_Beaudoin

You will run into these issues with any brand of VFD drive. The problem is not with the drive, it's the mechanical setup! You WILL have to eventually correct that...much easier to do that now...and save yourself all the headaches.
 
>Is this a problem with just this brand of drive (YASKAWA) or
>a problem of any drive. Is the drive not supposed to be able
>to send speed all the way down to 0 rpm?

From the manual:
Parameter H3-03 sets the level of the selected input value that is equal to 10 Vdc input at terminal A1 (gain).
Parameter H3-04 sets the level of the selected input value that is equal to 0 V input at terminal A1 (bias).
Use both parameters to adjust the characteristics of the analog input signal to terminal A1.

Setting Examples
A Gain H3-03 = 200%, bias H3-04 = 0, terminal A1 as frequency reference input (H3-02 = 0):
A 10 Vdc input is equivalent to a 200% frequency reference and 5 Vdc is equivalent to a 100% frequency reference. Since
the drive output is limited by the maximum frequency parameter (E1-04), the frequency reference will be equal to E1-04
above 5 Vdc.

But as Gerald said, you may run into heat dissipation problems at low speeds. Most motors (i.e. TEFC or Totally Enclosed Fan Cooled) have fans on the end that are driven by the motor and blow air over the unit. If the motor is going that slow, the fan is going that slow.
 
Top