D4 Datasheet - UMS

D4
Tree growth sensor Dial-Dendro © UMS-electronic
Permanent and automated measuring of circumferential growth
Easy data acquisition with any standard measuring system
Compatible with datalogger, field-bus, handheld or PC data acquisition boards
Easy mounting, low maintenance and extreme roughness
Measuring range easily expandable through adjusting of the cable
Minimisation of the friction on the bark and dependence on temperature
Prevention of callousing and healing over
Fastening screw
Trunk wood
Cable-fixing
Bark
DIAL-DENDRO
R
Cable-guidance
Electrical sensor
(Conductive plastic potentiometer)
Cable
Tree
Teflon-net
Sealed plug
Trunk wood
Data transmission
R
DIAL-DENDRO - UMS-electronic
The DIAL-DENDRO ® UMS-electronic is a compound of
the DIAL-DENDRO ® made by FOB, Salzburg with a
compact-sized electrical sensor to offer a permanent and
automated acquisition of data.
A variation in the trees circumference is conducted to
the DIAL-DENDRO ® by a cable tied around the trunk
and is mechanically transformed into a rotation. Through
a coupling flange free of play the rotation leads to an
angular movement and, therefore, to an electrical signal
in a conductive plastic potentiometer.
The dendrometer base is fixed to the trunk with two
screws anchored in the trees wooden pith. A space of
2cm between mounting plate and bark is left to prevent
callousing and healing over which would cause errors of
measurement. A net made of Teflon is placed between
cable and bark to reduce the friction of the cable and to
protect it from icing, resin and callousing.
The device is suitable for measuring the circumferential
growth of trees with diameters of 15 cm and more, and
with an accuracy of 10 µm.

Electrical Sensor
Different than sensors measuring capacity or inductivity with
AC-voltage, conductive plastic potentiometers need no
extra electronic. The potentiometer is measured as an DCbalancer
(never as a variable resistance) and offers a DC
voltage signal which is compatible with any datalogger, fieldbus,
handheld instrument or PC-board. A constant power
Fixing the Dendrometer
Pilot-drills are attached first, then the ground plate is fixed
with screws leaving a space of 2cm between ground plate
and bark. This will prevent errors of measurement caused
by callousing, healing over or responding of the ground plate
to the growing tree. As soon as the bark has grown close to
the ground plate, the device is just pulled out further.
Materials
Measuring cable and Teflon-net have a low dependence on
temperature. The cable is made of INVAR-steel, which
outstanding specifications are a dependence of temperature
supply must be provided. The potentiometer output signal
has linear characteristic. For example, with 10 V DC power
supply, a circumferential variation of 1 mm will cause a shift
of 116 mV in the output signal voltage. This is independent
from the starting point and it's output signal, because only
relative circumferential variations are measured.
The Teflon-net will reduce the friction of the cable on the
bark. The cable-guidance is bended for a close fit depending
on the diameter of the tree. For expanding the measuring
range, the cable can be fixed in it's position before the disk is
turned back to the starting position. A detailed instruction is
supplied.
of only 1 µm/mK and a high corrosion resistance. All
elements are stainless. Potentiometer and plug are
waterproof (IP65).
Technical Specifications Art. No. D4
Sensor
Measuring range
Power supply U B
Linear characteristic
Output signal
Dependence on Temperature (device)
Dependence on Temperature (cable)
Linearity
Accuracy
Repeatability
Max. current
+/-0.3%
optional
< 0.01%
4.5 mA
Conductive plastic potentiometer
0 .. min. 75 mm circumferential growth
5 ... 10 V DC , stabilised
11.6 mV/mm * U B /V
0 V ... approx. U B