ISA Interchange

Welcome to the official blog of the International Society of Automation (ISA).

This blog covers numerous topics on industrial automation such as operations & management, continuous & batch processing, connectivity, manufacturing & machine control, and Industry 4.0.

The material and information contained on this website is for general information purposes only. ISA blog posts may be authored by ISA staff and guest authors from the automation community. Views and opinions expressed by a guest author are solely their own, and do not necessarily represent those of ISA. Posts made by guest authors have been subject to peer review.

All Posts

Linear Relationships for 4-20 mA transmitters

Linear Relationships for 4-20 Transmitters

A standard electronic pressure transmitter has a range of 50 to 250 psig (345 to 1724 kPa gage), and the pressure is 150 psig (1034 kPa gage), what is the output in mA?

a.   4.0 mA

b.   12.0 mA

c.   13.6 mA

d.   50.0 mA

 

The formula I use for the above question is as follows:

((Input – Input Minimum) / (Input Max –Input Min) * 16)) + 4 = mA

 

Therefore 150-50 =100

And           250-50=200

100 divided by 200 = .5

.5 * 16 = 8

And 8 + 4 = 12 mA

 

If the milliamps were given, this formula would solve for the input.

(((mA Output – 4 mA) / (mA MAX – mA MIN)) * (Input Max – Input Min)) + Input Min = Input

Therefore 12-4 = 8

And 20-4 = 16

8 divide by 16 = .5

250-50 = 200

.5 * 200 = 100

100 + 50 = 150 psig

 

The above formulas are for linear transmitters and URV= Input Max and LRV=Input MIN.

The answer is B.

Mark Weisner
Mark Weisner
Mark Weisner is a technical specialist at ISA.

Related Posts

My ISA Journey

My ISA journey thus far has been one ripe with growth and knowledge. I’m lucky to say it has been one of ...
Prabhu Soundarrajan Feb 22, 2024 12:12:00 PM

Intelligent Automation: Overcoming Challenges for Seamless Implementation

In the ever-evolving landscape of technological advancements, intelligent automation stands out as a beac...
Amol Kakade Feb 20, 2024 8:00:00 AM

Securing the Future: IoT Product Testing and Information Security in Smart Manufacturing

The Information of Things (IoT) industry is booming. Data collected by Statista shows that the sector gre...
Katie Brenneman Feb 15, 2024 10:19:28 AM