I'm using the following VFD for a 3-phase AC motor: ACS550 user manual

I want to monitor the power consumed by the motor and the actual rpm.

On page 28 and 78 it meantions:

• Analog output AO1: Frequency

• Analog output AO2: Current

It seems I can use these outputs to monitor the current and the freq.

But what is AO2 here in mA? Is this the indicator for stator current in mA?? If so how can I convert it to the real current??

And similarly is Analog output AO1 the actual rpm?? And how can I convert it to the real rpm?

  • \$\begingroup\$ (Without reading the manual) AO1 is the RPM of the drive. Induction motors slip a little so the actual RPM may be slightly less. To get a actual RPM you'll need an encoder or proximity switch pulse, feed that into your PLC and calculate actual RPM. \$\endgroup\$ – Transistor Feb 15 '16 at 12:34
  • \$\begingroup\$ do you mean this device measures stator voltage frequancy as rpm? \$\endgroup\$ – user16307 Feb 15 '16 at 12:41
  • \$\begingroup\$ I wouldn't think it measures it. It sets it. The VSD is controlling a rotating field. The induction motor "slip" is what generates the torque. I don't think you can detect the actual frequency from the VSD unless you use an encoder. \$\endgroup\$ – Transistor Feb 15 '16 at 13:03

Well, it is all in the manual if you just read it.

Parameter Code 1507 - Sets the value for AO2 (which by default is Parameter 104 = Current).

Parameters 1508-1512 are the rest of the settings. Scaled Min / Max / Filter /Etc.

Parameter 104 says

0104 CURRENT 0.0…2.0 · I2hd 0.1 A (where I2hd is drive current).

I will leave the rest up to you.

  • \$\begingroup\$ Thanks but just one more thing : Is AO2 the total stator current scaled or the speed? \$\endgroup\$ – user16307 Feb 15 '16 at 15:34
  • \$\begingroup\$ It can be anything, depending on Parameter #1507. By default Parameter #1507 is set to 104. This is telling the VFD that AO2 (Parameter 1507) should output Parameter (104, which is Current). Parameter 1507 can be changed to output other things too. \$\endgroup\$ – Tyler Feb 15 '16 at 15:53
  • \$\begingroup\$ oh thanks so is that the total stator current? did i get u right? sorry just want to be sure what im doing \$\endgroup\$ – user16307 Feb 15 '16 at 15:57
  • \$\begingroup\$ If you read in the manual what Parameter 104, it will give you more information then I can here. But here goes; Parameter "0104 CURRENT 0.0…2.0 / I2hd 0.1 A" (where I2hd is drive current). So, depending on other Parameters (1508-1512) you get the % of drive current. So, if 104 is reading 1.50 then the drive is outputting 150% of drive current. If you find this answer helpful, please don't forget to up vote, and if it solves you question mark it as accepted. \$\endgroup\$ – Tyler Feb 15 '16 at 16:01
  • \$\begingroup\$ is drive current I2hd nominal current of the motor? \$\endgroup\$ – user16307 Feb 15 '16 at 16:45

Like any other VFD it needs some parameter settings about scaling the analog input/output. Find further in operating manual.

  • \$\begingroup\$ I cant find any more info in this pdf \$\endgroup\$ – user16307 Feb 15 '16 at 12:17
  • \$\begingroup\$ @user16307 Sorry, I won't read the manual for you. \$\endgroup\$ – Marko Buršič Feb 15 '16 at 12:23
  • \$\begingroup\$ even if i find it it is not clear if A02 represents the total stator current.. im confused \$\endgroup\$ – user16307 Feb 15 '16 at 12:29
  • \$\begingroup\$ Page 92 has information about max current limits.. the fact it's 20ma says to me that max speed = 20ma, standard industrial instrumentation interface - current loop, Also you may need to find 'another manual or instructions' for the fine detail at the library .. see second to last page I think. \$\endgroup\$ – Spoon Feb 15 '16 at 12:35
  • \$\begingroup\$ I was planning to monitor the power using AO2. So it is not stator current scaled down to mA? Is it speed? \$\endgroup\$ – user16307 Feb 15 '16 at 12:38

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