Operating Principles - shelyak SENTINEL PF0007 Guide Utilisateur

2.3 - Operating principles

Your Sentinel:
messures cloud coverage
●
measures sky brightness
●
measures strength and direction of the wind
●
measures external temperature
●
measures ambiant humidity
●
detects rain or snow
●
stores data in its internal memory
●
can trigger your observatory closure
●
generates graphs and transfer them by FTP to your web site
●
Main purpose of your Sentinel is to indicate you if you can open your observatory or if you have to
close it because weather conditions aren't optimal anymore. Internal relay can operate 1A/250V
power and be directly connected to a Dome Tracker which interface with your observatory motor
drivers.
But your Sentinel can also perform a weather monitoring of your observing site and give you useful
statistics. It works with or without PC: you can leave your Sentinel alone and collect internally
stored data from time to time.
Your Sentinel messure cloud coverage by measuring sky temperature around 5-14µm with an angle
around 80°-120°. A clear sky is typically 20°C cooler than external temperature while a cloudy sky
would be around the same temperature.
Some clouds are sometimes not detected (cirrus), but they usually do not give rain. On the other
side, some clouds can be very high and be detected only with the rain.
Those limites do not prevent an efficient use of your Sentinel but you have to take it into account in
your observing strategy. Always use alternative sources of weather data to decide.
Cloud detector won't work behind a glass or a plastic
so keep its view clear. Also, your Sentinel has an
internal heating system to eliminate water on the
rain/snow detector;
perturbate ambiant temperature sensor; make sure
to take this into account when setting up your
closure limits.
Rain/snow detection
resistance between two metal plates. If measures
are done on a frequency defined by the user,
detection is almost immediate in case of rain or
snow.
Sentinel – User Guide (Français / English) – DC0011C
this heating can
is done by measuring
slightly
Make sure your emergency
Alway check that no object
or person is in the way.
ATTENTION !!!
closure system
is risk proof.
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