« previous next »
Pages: [1]   Go Down

Author Topic: Measuring 4-20 mA current loop  (Read 1051 times)

0 Members and 1 Guest are viewing this topic.

Offline SaullTopic starter

  • Contributor
  • Posts: 16
  • Country: 00
Measuring 4-20 mA current loop
« on: January 18, 2018, 07:18:39 pm »
Hello,

On Danfoss VFD I have one analog output (4-20mA) which outputs VFD frequency. I would like to measure this output with multi meters mA range, do I need any resistor between multi meter and VFD output terminals or I can probe directly ?
Logged
 

Offline Wimberleytech

  • Super Contributor
  • ***
  • Posts: 1133
  • Country: us
Re: Measuring 4-20 mA current loop
« Reply #1 on: January 18, 2018, 07:45:27 pm »
Probe directly
Logged
 

Offline LaserSteve

  • Super Contributor
  • ***
  • Posts: 1281
  • Country: us
Re: Measuring 4-20 mA current loop
« Reply #2 on: January 18, 2018, 08:14:04 pm »
If it has output short detection, probe with 150 or 270 Ohm resistor in series with meter. Otherwise probe directly.

Steve
Logged
"What the devil kind of Engineer are thou, that canst not slay a hedgehog with your naked arse?"
 

Offline IanB

  • Super Contributor
  • ***
  • Posts: 11859
  • Country: us
Re: Measuring 4-20 mA current loop
« Reply #3 on: January 18, 2018, 08:52:08 pm »
Some multimeters have a 4-20 mA mode and will indicate % of scale directly.
Logged
 

Offline bitbanger

  • Regular Contributor
  • *
  • Posts: 161
Re: Measuring 4-20 mA current loop
« Reply #4 on: January 19, 2018, 04:01:59 am »
To add to what Steve said: the VFD should specify a maximum output load for the 4-20mA output (typ around 600ohms), so any series resistor below this spec will be fine.

That said I personally have not encountered a Danfoss with short circuit monitoring on 0-20/4-20 out.
Logged
 
Pages: [1]   Go Up
« previous next »

Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf

 


EEVblog Main Site EEVblog on Youtube EEVblog on Twitter EEVblog on Facebook EEVblog on Odysee