current sensor for 3-phase AC motor??? help???

[Kel'Thuzads]

Hi! everybody.
I want to measure current of 3-phase AC motor.
my method :
- use TI
- current output from TI is rectified by diode bridge.
- after is connected to PGA, --> 0-10V
- then is connected to analog module of PLC

I haven't been tried, for do not make sure. is there another which method another?
please help me !
Thanksssss.

 

[turbina]

with linear hall-effect sensor? it's ok for you

 

[ace1903]

Other way is to swap places of diode bridge and pga. Voltage drop on diodes is betwen 0,4 and 1V and this can introduce non linear transfer caracteristic. Also diode bridge can be obmited if one pin of secundar winding is biased to Vcc/2 and rectifying is done by software.

 

[Kel'Thuzads]

thank you! I will try it. I hope to will succeed .

 

[kender]

I think, you don't have to use a difference opamp. I would ground the bottom of the bridge and use an inverting or non-inverting opamp. Another $0.02