#### A current-to-pressure transducer is used to convert a 4-20 mA electronic signal into a 3-15 PSI pneumatic signal.

This particular transducer is configured for reverse action instead of direct, meaning that its pressure output at 4 mA should be 15 PSI and its pressure output at 20 mA should be 3 PSI.

Calculate the necessary current signal value to produce an output pressure of 12.7 PSI.

## 3-15 psi to 4-20mA Conversion

We are solving this problem using **standard 4-20mA conversion Formula**. **Click here for formula**

Reverse-acting instruments are still linear, and therefore still follow the slope-intercept line formula y = mx + b, albeit with a negative slope:

Calculating and substituting the slope (m) value for this equation, using the full rise-over-run of the linear function.

Note how the “rise” is actually a “fall” from 20 milliamps down to 4 milliamps, yielding a negative value for m:

Therefore, a current signal of 7.07 mA is necessary to drive the output of this reverse-acting I/P transducer to a pressure of 12.7 PSI.

## 9 comments

Super

How to calculate the same for direct acting i/p transducer?

Highly beneficial knowledge

Dear Sir,

Please explain in detail about P & ID diagrams.

Thanks,

Girish T.

the given value of 4.5 mA is 0 psi and the 19.5 mA is 100 psi . how about if 40 psi how many mA ?

Maybe we can use algebra here 19/100=x/40… X=7.6 maybe????correct me

Super sir

Hello Sir,

I am facing a problem as you provided formula,if it’s any mistake from my side please correct me.

My question is 15 PSI should be 20MA

Hence =(-16÷12)= -1.3333

=(-1.3333×15PSI)= -19.9999

=(-19.9999)+24= 4.0 MA

Why I get 4MA?

If any mistake please correct me

Thanks

Rohith

Hi,

Please check the question again, the calculation provided for Reverse action, 15psi = 4mA and 3psi = 20mA.

You can use this formula for linear action > Click here