Most of the PAPI took a longer time to defrost at -5°C and -10°C than at -20°C. This can be explained by the type of ice. At -5°C and -10°C, the ice is clear, at -20 °C, the ice is white.
The best average performance was achieved by Crouse-Hinds PAPI.
The best defrosting time was achieved by Siemens PAPI with wired cover glass at -20°C in 5 minutes.
The most energy efficient PAPI is the Crouse-Hinds.
Minimum Current Tests:
What was simulated during this test is a snow storm or ice storm depending on test temperature, on a PAPI already energized. We obtained three types of results: The ice is not melting at all, the lens defrosts partially or the lens defrosts instantly.
We did two summary tables (completely and partly defrosted) because even if the lense is partly defrosted, the signal can be considered complete based on our criteria. It is to be noted that even if we consider the signal to be complete during the tests at 12' from the receiving panel, it does not necessarily means that the signal will be complete in the "real world" (at 1 mile).
Only Crouse-Hinds PAPI can meet the completely clear lens requirement at every temperature that we tested.
Siemens and Cegelec PAPI can meet the completely defrosted lenses at temperature above -10°C. At temperature below -10°C, there is always ice remaining on the edges of the lenses.
For partly defrosted lenses, the minimum current vary from 5.5 Amps to 6.6 Amps at -30°C.