MME-1000 LVDT Signal Conditioner Tutorial

TE Connectivity Macro Sensors EAZY-CAL MME-1000 = LVDT Signal Conditioner Tutorial

Hello, and welcome to the macro sensors Eazy-Cal calibration instructional video.

The Eazy-Cal is the easiest single-channel LVDT signal conditioner to use. By employing a virtually effortless front panel fingertip calibration routine, field calibrations are accomplished in mere seconds.

This video will encompass suggested calibration equipment, mechanical mounting of the Eazy-Cal, electrical input and output connections, LVDT wiring, core positioning, and the calibration routine itself.

For this demonstration, we will be using a regulated DC power supply set, the plus 24 volts DC, a digital voltmeter, and a microcode to digital micrometer with three daps. The head of the digital micrometer is attached to the end of a custom test fixture in which the LVDT will be positioned during calibration.

All of the input and output voltage connections are made on the bottom side terminals while the LVDT is connected to the topside terminals. Looking at the bottom side, the supply voltage has been connected to terminals D1 and D2 with plus 24 volts DC going to terminal D1 and ground or zero going to terminal D2.

The digital voltmeter which will read the voltage output of the Eazy-Cal has been connected to terminal C1, which is the positive DC voltage output and to terminal C2, which is ground or zero. The LVDT is connected to the top set of terminals on the Eazy-Cal. The two primary wires are connected to terminals B1 and B2 with yellow connected to B1 and brown connected to B2.

The secondary wires connect to terminals A1, A2, and A3 with red connected to A1, black connected to A3, and both blue and green, which are the center tap wires, connected to A2. If you're using an LVDT, which has a shielded cable, the shield may be connected to terminal B3, but it is not necessary. A full wiring diagram can be found on the label located on the side of the Eazy-Cal along with complete calibration instructions for easy reference.

In addition, each Eazy-Cal is supplied with the user’s manual which contains additional information on calibration, LED lamp functions, electrical specifications, dimensions, mounting instructions, and other helpful notes and tips.

The Eazy-Cal is designed to easily attach to a standard 35-millimeter din rail. To attach, just hang the Eazy-Cal onto the top lip of the din rail and push it towards the rail until you hear a click. Then, you can pull the metal clip down and release it when in position. To remove the Eazy-Cal, pull down on the metal clip and simply lift away.

For this demonstration, we will be using macro sensors PR 750-500 AC LVDT. This LVDT has a plus or minus 0.5-inch range or a 0 to 1.0-inch total stroke, with the Eazy-Cal having a 0 to +10 volt DC output. This will make it very easy to correlate the displacement of the LVDT with the DC voltage output of the Eazy-Cal after calibration has been completed.

I will now insert the LVDT into the test fixture and visually center the core within the coil. Now with all the connections made and the LVDT positioned into the test fixture, we will apply the plus 24 volt DC supply voltage to the Eazy-Cal. The operation/calibration or opt cal LED indicator lamp will illuminate indicating power.

We must now allow three minutes for the Eazy-Cal to fully warm up. With the Eazy-Cal now fully warmed up, we are ready to initiate the calibration procedure. This is accomplished by simultaneously depressing and holding the zero and full-scale buttons for three seconds or until the red opt cal LED indicator lamp starts to blink, signifying that the calibration mode has been entered.

It is important to note that once the calibration procedure has been initiated, an internal timer starts a countdown and will allow 90 seconds for the completion of the calibration routine. If it is not completed within the allotted time, the Eazy-Cal will automatically revert to normal operation mode and its previous calibration settings.

You also have the option to manually abort the calibration sequence at any time by simultaneously depressing and holding the zero and full-scale buttons for three seconds. This will also cause the Eazy-Cal to revert to normal operation mode and its previous calibration settings.

Now that we have entered calibration mode, you will notice that the plus and minus LED lamps above and below the null LED indicator lamp will flash on and off as the LVDT coil is passed up and down the core. These lamps provide a visual position indication of the coil relative to the core. When perfectly centered, the null LED indicator lamp will be steadily illuminated, meaning that the LVDT is at the center of its total stroke or at null. We then position the coil in the test fixture as closely as possible to null and lock the coil in place.

Next, we adjust the digital micrometer head until the null LED indicator lamp is steadily illuminated. Being at null, we now reset the digital micrometer readout to zero.

Next, we'll displace the LVDT core by negative 0.5 inches using the digital micrometer head and readout. This will take us to the negative end or zero inch position of the LVDT stroke range. In relation to the Eazy-Cal, this will be the zero volt DC output position.

Next, we enter the zero calibration point into the Eazy-Cal by momentarily pressing the zero push button. The three positional indicator lights on the front panel will then briefly sequence providing positive feedback that the zero points have been stored. The positive position of an LED lamp will then illuminate. We now reset the digital micrometer readout to zero.

Next, we displace the LVDT by plus 1.0 inches. When the final position has been reached, we entered the full-scale calibration point into the Eazy-Cal by momentarily pressing the full-scale push button. The positive position indicator lamp will turn off and the opt cal LED lamp will become solidly lit, indicating the calibration has been successfully completed and the normal operation mode is engaged. We now observe that the output voltage of the Eazy-Cal has displayed on the DVM is +10.02 volts DC with +10.00 volts DC being nominal for the +1.0 in stroke position. We now displace the LVDT back to the plus 0.5-inch position and we observe the output to be plus 4.99 volts DC with plus 5.00 volts DC being nominal.

Finally, we displace the LVDT back to the 0-inch position and we observe the output to be 0.00 volts DC. Calibration has now been successfully completed and the Eazy-Cal is ready for normal operation. If at any time during the calibration sequence a positional error has occurred or a button was pressed out of sequence, the null LED indicator lamp would have begun to blink red. These errors are fatal and the calibration sequence must be aborted and reinitiated. The exact reasons for these type errors are explained in the user's manual which came with your Eazy-Cal and can also be found on our website.

Thanks for viewing the macro sensors Eazy-Cal video calibration tutorial. Remember to visit our website at www.macrosensors.com for all of your linear and rotary position sensing needs.