
BF5 User Manual v
2.
3
Introduction
9
Construction
Seven cosine-corrected photodiodes are arranged under a patterned,
hemispherical dome, along with a levelling bubble, a desiccant-status
indicator, and a red light emitting diode (LED). The LED flashes when the
photodiodes are powered up for a reading.
There are two panel mounted sockets for communications:
An 8 pin, M12 male analogue socket for connection to SunScan or to
a data logger.
This can also connect to a logger warm-up power supply for the BF5
sensor and to a separate power supply for the heater.
A 5-pin M12 male connector serial port for connection to a PC or to
the SunScan radio link option.
The serial port is provided for checking real time readings, for changing
the output units, and for logging data directly to the PC.
A camera tripod type connector (1/4” BSW thread) is fitted to the base.
Heater
The BF5 is fitted with a thermostatically controlled heater for protection
against frost and condensation. Its use is recommended for logging
applications. It requires a separate external 12V DC power supply.
Use of the heater stabilises the internal temperature of the BF5 in cold
conditions, keeping the dome free of frost and resulting in greater
measurement accuracy.
The heater consists of two 15W resistors fixed to the shadow-mask.
When power is applied to the heater it works as follows:-
If the external temperature is above 5
C, the heater provides 2W,
reducing to zero above 35
C.
This is sufficient to remove condensation and dew.
Whenever the temperature drops below 5
C the heater is increased,
to full power below 0
C - to remove snow or ice.
At zero wind speed a BF5 at minus 20
C will become snow and ice free in
30 minutes once power is applied to the heater.
At 2m.s
-1
wind speed the dome will remain snow and ice free down to
minus 10
C.
Warning
:The bare heaters can get hot enough to burn your skin when on.
Do not operate the heaters with the dome removed.
Warning:
Ensure the heater ground is isolated from all other BF5 ground
connections. If possible use a data logger with differential sensor inputs.
See also page 21