Product Manager, Tim Kelley, demonstrates how to calibrate a 4-20 MA.
Hi, I'm Tim Kelly from Gem Sensors. I'm the Product Sales Manager for our Continuous and Connectivity product lines. What I'm here today to talk to you about is calibrating our 4 to 20 milliamp signal conditioner.
The conditioner I have in front of you here is commonly found with our float type transmitters and our SureSite product line. To do the calibration what you'll need is a 24 volt power supply DC voltage, a multimeter, a screwdriver or tweaker, and a potentiometer in the range of 1,000 ohm to 2500 ohm. To wire this up properly you'll take your 24 volt positive DC into pin 5. Pin 4 will go to your multimeter. Your common leg of the multimeter back to your negative leg of the DC power supply and the potentiometer into pins 1, 2, & 3. The red into 1, black into 2, and the third will have the wiper arm or the white wire.
Once you have your potentiometer connected we want to establish the direction of raising and lowering its output. Turning the potentiometer clockwise, you'll notice on the multimeter that the output goes towards 20 milliamps. Counterclockwise the output drops towards 4 milliamps. Let's raise it all the way clockwise. Once we've done that we now can adjust on the span potentiometer and tweak that down towards the 20 milliamps.
Once that's done we take the potentiometer fully counterclockwise and do the null potentiometer. Now these do affect each other so what we want to do is this 2 or 3 times total. If we bring the potentiometer fully clockwise you'll notice that the output is actually changed and we tweak that back towards the 20 milliamp point. As I said doing that 2 or 3 times will pull that into your 4 and 20 points. Once you're done your unit is fully calibrated. If you do not have a potentiometer handy you can replace that by using a simple jumper wire. Placing it from terminals 2 and 3 to set your 4 milliamp point and 1 and 3 to set your 20 milliamp point. Once you've completed the calibration process the signal conditioner is ready to be used on transmitters of any length.
Should you have any questions on this calibration procedure or any technical questions on any Gems product line feel free to give us a call at 1-800-378-1600. Thank You.