I have a 4-20 mA Power Transducer to measure output power for 3 Ph. Transformer. It shows 4 mA with TRAFO in  no load condition , but when TRAFO is in load , the trans. shows 0.90 mA.  Plz Explain

May be the polarity of CT connections is reversed and the transducer interpretes it as reverse power.

Dear Meng-Ho , Is it possible for a 4-20 mA transducer to show output as 0.90 mA ? Shouldn't its minimum output be 4 mA ?

Mr. Ngu has identified the most likely culpret..... check that 1st. IF that doesn't solve the problem, check your shield grounding (ground in 1 location only) and recheck the calibration on transducer.

Hi Abhishek
I would check the followings:
1) Is the transducer properly callibrated? I suppose, 4mA should be callibrated to 0A in CT, and 20mA should be callibrated to the transformer's rated current + 25% or something like this.
2) Is there a chance that the transducer output is connected to several readers in parallel? If yes, 0.9mA is a result of current division between multiple devices.
3) Is there a chance of damaged transducer?
Good luck,
Ilia

Polarity and sequence of both current voltage to rechecked

Thanks Mr. Ngu,Ilia,John & Mr Nair.......... I will reverse the CT polarity & get back with the result.......Thanks again....

Is there an out-of-range setting for the transducer? Some transducers have settings for desired output signal when 1) out-of-range and 2) open cirquit 3) short cirquit. If the transducer is programmable with a laptop check the error settings. Often the output choice for errors 1-3 is 0mA or 21mA in case of a 4-20mA output.