Use 4-20 mA

[Mario Sosa]

Hello i need help with a FES compressor, this one have a micromaster control i want to control the compressor motor with the option of 4-20 mA for a frecuency drive but if i measure with a amp-meter i don get the 4-20 mA, i get a wrong measure what can i do,
Thanks for your help

[Brian_UK]

I don't fully understand your question but do any of the documents from here help you?

http://support.automation.siemens.com/WW/llisapi.dll?func=cslib.csinfo&lang=en&objID=10804926&subtype=133300

[Mario Sosa]

ok i dont have trouble with the drive i have trouble with the control of the compressor.
The compresor control its a FES MICROMASTER CONTROL the drive its a Mitsubishi Electric one. In the main board of the FES control there is an analog output 4-20 mA but there is not 4-20 there is 230 mA. and i dont know why, i hope you can help me. or of you know where can i get a user manual for that compressor that will be fine.

[Brian_UK]

I can not see anything in the manual to suggest other then 0 - 20mA on the KL terminals.

Is your test meter suitable for the task?

Is the unit faulty?

[Mario Sosa]

if you have the manual of the compressor, ?can you tell me where can i get it¿

[Magoo]

To test the 4-20ma output you need to set your test up as a shunt, so the meter is in loop with output. Or everything goes through your meter and set scale to DC milliamps. If the processor only accepts ... what ever input you will need a signal convertor to change drive output to something the processor can interprute. Check out RS calalogue for variable options.
magoo

[NoNickName]

Do you have trouble with the analogue input or analogue output from the drive?

[Mario Sosa]

Do you have trouble with the analogue input or analogue output from the drive?
no mi trouble is with the main board of the FES micromaster main board

[Brian_UK]

if you have the manual of the compressor, ?can you tell me where can i get it¿
No, I am only reading the Micromaster instructions as per the link I gave earlier.

[Peter_1]

....In the main board of the FES control there is an analog output 4-20 mA but there is not 4-20 there is 230 mA. ...
Or the controller is broken or your measuring device is defective. It must lay between 4 or 20 mA.

[NoNickName]

no mi trouble is with the main board of the FES micromaster main board

That doesn't answer my question.

[orob]

Your 4-20 mA output is putting out 230 mA? Did you test this over a load resistor, the motor, or just across a meter? The motor you are driving is a frequency signal input? Your controller board is outputting a 4-20 mA frequency drive?

[jcook1982]

4-20mA has to be assigned a range. If not than you never know how many mA equal your unit of measure.

[trieuphu]

Mario,
jcook is right. You need to know what is the span for min/ max to correct measure 4-20ma and it is a closed loop, you must insert a load to find out the current. I think the DRIVE need a current input to control not output.
It's better if you tell me what are you going to do with 4-20ma.

[trieuphu]

Mario,

Here is an example. You want to control temperature of a room between 70F-80F and you must have a current sensing device that convert from temperature to current (70F = 4ma, 80F=20ma). You need a power supply to work with or you may use 4-20ma analog output from the DRIVE but the feeback must return to the drive input to change frequency of the drive and driven the compessor to speed up or slow down accordingly to the setpoint. Otherwise, automation is not a close loop and nothing will work.

[CAPTAINBIRDSEYE]

check the data sheet some drives are settable to operate either 0-10vdc or 4-20mA you may check dc volts your probably outputting dc voltage mate