2 VFD - 1 Transmitter Signal.

[SPBDASAN]

Hi,
I want to control the 2 VFD through 1 transmitter 4~20mA signal. how to control and do I need to add any signal isolator, please advice me on this. Thanks in advance.

[Brian_UK]

What make and model VFD do you have, we cannot see it from here.

What does the instruction book say?

[SPBDASAN]

Vacon VFD
model no.:NXS00875A5H0

[Peter_1]

You can normally do it perfectly with one current loop, putting the 4-20 mA signal in serial (current is the same in a serial circuit) through both VFD's but you better split it to avoid possible interference.

[SeanB]

If the transmitter is powered and drives the receivers then you can put them in series, provided that they do not ground the receiver signal. If you have a separate 24V power supply and an isolated transmitter then this is also acceptable. If the VFD units provide the power then you will have to disable one of them from powering the loop and use it as a isolated receiver. If you cannot then you will need to get a loop isolator to duplicate the signal for the one. As well check that you do not run into voltage drop issues running the 3 units in series, some units ( transmitter and receiver) have a high enough voltage drop across them that you can only use a single transmitter and a single receiver across a 24V supply.

[SPBDASAN]

Hi all,
Thanks for your prompt reply. I planed to use signal Isolator to avoid the interference.

[goshen]

Hi
you may connect 2 units in series to one transmitter with no problem,i have done it before ,with vacon drives.
for example on cooling towers,
good luck