404 Auto Calibration

Auto Calibration

Requires version 3.00 and higher

This assumes that all Location and both axis Motor set up has been completed, wiring is completed and you are ready to track the sun.

Sometimes solar trackers can lose position due to mechanical slop, hysteresis or external forces. By enabling and configuring Auto Cal, the Tracker IPm now utilizes the lower limit switch to recalibrate the tracker each day. You store the memorized calibrated value of the limit switch in a non-volatile register which is passed to the present position value “Pv” whenever the switch is closed.

Tech Tip:

This will permit the tracker to recalibrate itself every morning or permit an operator to easily recalibrate remotely. Simply drive the tracker to the lower limit switch in Manual and return it to Auto and it is re-calibrated.

Set Up

You do not have to know the exact position of the lower limit switch to set it’s value. Simply estimate and calibrate it using the sun using this procedure.

Azimuth (Disregard for Single Axis or Parabolic Trough)

1. Either through the I/O Tool Kit’s Test I/O (Tab VDO) or Web Control, ENABLE Auto Calibration by turning on AZI01_AUTO_CAL.

2. Enter the approximate (estimated) azimuth in degrees of the minimum limit switch in AZIxx_ZERO. It does not have to be exact.

3. Now move the tracker to contact the limit switch. Put the Tracker IPm into MANUAL by turning off AZI01_AUTO and turning on AZI01_CALIBRATE.

4. Turn on AZI01_DN and wait for the tracker to stop moving when it contacts the limit switch. This is indicated by AZI01_ZMIN changing to On.

5. Turn off both AZI01_DN and AZI01_CALIBRATE

6. Turn on AZI01_AUTO. This should return the Tracker IPm to automatic tracking. This is when you calibrate the limit switch and you can do this any time while the tracker is in Auto.

7. If the tracker is not on sun, enter a value in degrees (including decimals) to AZI01_CORRECTION. The number can be a rough estimate and can be plus or minus depending which direct you want to go. By looking at the results, you can change this number as many times as needed until the tracker is on sun while AZI01_AUTO is in AUTO. Then you are done with azimuth Auto Cal. The next time the tracker contacts the limit switch it will add the correction to the limit switch’s azimuth and render it’s exact position in memory.

8. The calibration is complete. By repeating steps 3 – 6 you can prove the accuracy of the calibration.

Note the soft limit AZI_MIN_DEG and the AZI_MIN_DEG set  in I/O Tool Kit’s Test I/O (Tab VFI)  or Web Control must be a lower value than the calibrated value of the minimum limit switch otherwise the tracker will never reach the limit switch.

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Altitude (same procedure)

1. Either through the I/O Tool Kit’s Test I/O (Tab VDO) or Web Control, ENABLE Auto Calibration by turning on ALT01_AUTO_CAL.

2. Enter the approximate azimuth in degrees of the minimum limit switch in ALTxx_ZERO.

3. Now move the tracker to contact the limit switch. Put the Tracker IPm into MANUAL by turning off ALT01_AUTO and turning on ALT01_CALIBRATE.

4. Turn on ALT01_DN and wait for the tracker to stop. This is indicated by ALT01_ZMIN changing to On.

5. Turn off ALT01_DN and ALT01_CALIBRATE

6. Turn on ALT01_AUTO. This should return the Tracker IPm to automatic tracking. This is when you calibrate the limit switch but you can do this any time.

7. If the tracker is not on sun, enter a value in degrees (including decimals) to ALT01_CORRECTION. The number can be a rough estimate and can be plus or minus depending which direct you want to go. By looking at the results, you can change this number as many time needed until the tracker is on sun while ALT01_AUTO is in AUTO. The next time the tracker contacts the limit switch it will add the correction to the limit switch’s azimuth and render it’s exact position in memory.

8. The calibration is complete. By repeating steps 3 – 6 you can prove the accuracy of the calibration.

Note the soft limit ALT_MIN_DEG and the ALT_MIN_DEG set  I/O Tool Kit’s Test I/O (Tab VFI)  or Web Control must be a lower value than the calibrated value of the minimum limit switch otherwise the tracker will never reach the limit switch.