Farm
Electronics has supplied electronic RH sensors for use in
grain, onion and potato stores for over 20 years.
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Fig 1
Until around
5 years ago the 'Industry Standard' sensor was the Phillips
(Mullard) capacitive type (Fig 1). This sensor
is no longer manufactured which means sensors using
this element which come in for repair may have to be
scrapped and replaced with the new type.
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Fig 2
Farm Electronics
now use the Honeywell Sensor which also uses capacitance
to measure RH. (Fig 2)
The most popular RH sensor is the
type HC-L2 (Fig 3) which gives a 0-10 volt proportional
output of RH value. This sensor is supplied as standard
with all current RH controllers. It can also retro fit
all controllers with the 0-10 volt Phillips type sensor.
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Fig 3
The HC-L2 sensor can also be used
as a replacement for several other common type of sensor
found in use in agriculture today. (Such as Tryac, Robydome,
Stealth or Dolphine). Please contact us for advice.
HC-L2
RH Sensor Detail
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Fig 4
For more demanding applications Farm
Electronics manufacture the HC-H2 RH sensor (Fig 4).
This model uses a higher specification Honeywell sensor
which can withstand a wetter, dirtier environment for
much longer without losing accuracy or response.
HC-H2
RH Sensor Detail
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All electronic
RH sensors require periodic calibration checks to ensure
accurate response. This can only be done in a 'workshop'
environment and should never be attempted 'in situ'.
All Farm Electronics RH sensors use a waterproof plus
connection on the sensor itself.
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Simply unscrew the larger lock collar
on this plug and unplug the sensor cable. The sensor can then
be returned to Farm Electronics for re-calibration or repair.