Kipp&Zonen 2AP Sun Tracker - Manual (Page 56)

INSTALLATION AND SETUP
55
4.6.5.3 Tilt
Adjustment
The previous two sections describe how to fine-tune the 2AP, by correcting for errors in the initial
position of the 2AP, for overall assembly error, and how to align the Sun Sensor with the installed
radiometers. However, this is a momentary adjustment. Due to minor 2AP levelling inaccuracies the
path the 2AP follows will deviate from the path of the sun. This error will vary with the time of day.
The procedure in this section will compensate for a minor error in levelling only. Performing a Tilt
Correction requires several days of sun sensor observation data to be collected. When acquiring
observation data for the Tilt Adjustment the 2AP must be running in Active Tracking mode.
Note: To gather data for the Tilt Correction, Correcting Time mode must be disabled.
After the 2AP has gathered enough Sun Sensor observations reconnect the PC to the 2AP to
retrieve the data for processing. To correct for a minor error in levelling, the Tilt Adjustment applies
an offset to the Azimuth, Zenith, Longitude and Latitude values.
For the Tilt Adjustment procedure press the “Sighting Adjustment” button in the Main Menu and go
to page 3.
• To collect tilt analysis data, the Suntracker should be running in Active Tracking mode. If
the current mode shown in the box below is not "Active Tracking", select this mode from
the list on the right.
• Please consider ALL of the following points when you collect data for the tilt correction
analysis:
- Divide daytime into 10 equal time periods.
- Each time period should be at least 1 hour long.
- For each period, there must be observations during four separate days.
- Each observation requires 10 minutes of continuous sunlight.
- The time must be set accurately for the data collection period (within 10 seconds).
• You may finish this procedure now and go to the Suntracker monitor window. Go to the
Main Menu and press the “Run Suntracker” button. Allow the 2AP to collect tilt analysis
data for four sunny days, then return to the “Tilt Correction” procedure in Win2AP.
• If the 2AP has collected enough data to satisfy the above mentioned requirements,
reconnect your PC to the 2AP. Press the "Capture" button to download the data from the
instrument to a file. See figure 4.35.
• Press the "Calculate Tilt Corrections" button to calculate the tilt correction. If there have
been too few observations to accurately calculate the tilt correction, a warning message
will be displayed.
• Press the "Accept Corrections" button to perform the tilt correction. The 2AP will then
automatically adjust its orientation. It is recommended not to use the “Accept Corrections”
button if the warning “Too few observations” is shown.
• It is recommended that the tilt adjustment be repeated until the calculated tilt values are
less than 0.2 degrees. If data collecting is required, repeat step 2 and onwards.
• If tilt correction is no longer required, make a backup copy of the configuration file and move
on to the next section to set the 2AP in Active Time Correction mode. Press the "Save
CFG" button to save the Tilt Correction values to the backup of the ini. file.