Page 277 - TesaKatalogen

E le c t r o n i c L e n gth M easu r i n g E q uipme n t

For the acquisition of measured values, TESA offers a complete family of probes and mea-
suring instruments for the most demanding applications. The probes, supplied in standard
execution, do not need any form of adaptation. They function on the inductive half-bridge
principle.
The market offers other equipment using probes that partly operate on the principle of a
differential transformer and these are known as LVDT (Linear Variable Differential
Transformer) probes.
TESA also offers a range of probes compatible with other electronic equipment, using an
adaptor and a connector depending on the origin of the equipment. A description of TESA
standard half-bridge and LVDT probes is provided below.

Standard half-bridge probes for TESA equipment

Operating Principle +U Lf
All TESA electronic probes (value sensors) work based on the inductive +S
principle with mechanical contact of the workpiece. -S 0
They are fitted with a coil system inducing an alternating output voltage
that depends on the the position of the ferro magnetic core. When sym- LL
metrically positioned – i.e. at electrical zero – no voltage is impressed. -U
A move of the core, which may be attached to the measuring bolt while
the measurand is being taken, causes the inductance to change. This Inductive measuring
change generates a signal that is amplified and rectified before being S: Travel
displayed and further output. Depending on the instrument type, the U: Output current
analogue signal will be shown on a voltmetre or a numerical display after 0: Electrical zero
a digital transformation. L: Linearity range
Unambiguous assessment of the measurand (at bolt position) to the Lf: Linearity error
signal (displayed value) is the main characteristic of analogue value
acquisition. One of its distinct advantages lies in the value primarily dis-
played, which will be reproduced in the event of a power cut (switch-off
or power failure).

TESA Standard Half-Bridge Probes for TESA Electronic Equipment Ua Ua1,Fa1 U=KxX
These probes have two serial coils with middle output mounted side by Rs Uo
side, which are energized by a sinusoidal alternation signal at 13 kHz. G1
Both are linked together to a Wheatstone bridge over an additional half- -Ua Rch1
bridge. X

Wiring plan of half-bridge probes

TESA LVDT Probes Ua2,Fa2
These probes are based on a Linear Variable Differential Transformer Ua
(LVDT). They have three coils, i.e. one primary coil being energized by a
sinusoidal alternation at 5 kHz, and two secondary coils connected in Rs Uo U=KxX
opposite phase, which generate the output current proportional to the X
measuring travel. G2
Available upon request. Rch2

Wiring plan of LVDT probes

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