Thyracont VSC43MA4, Operating Instructions Manual

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4 Operation
4.1 General
Measurement Principle
The VSC43MA4 vacuum transducer has an internal piezoresistive ceramic
sensor. Under the influence of pressure a thin diaphragm is bent, on it's back a
resistor-bridge is applied. The bending forces the measurement-bridge to come
out of tune, which is a measure for the applied pressure.
Output Signal
The output signal 4.0 – 20 mA of your VSC43MA4 has a linear dependence on
pressure over the whole measurement range 1 - 1400 mbar.
Conversion of voltage signal and pressure is done according to the following
formula:
Warm-Up Time
The signal output of VSC43MA4 is available immediately after the unit is
connected to power supply.
4.2 Adjustment
The transducer is adjusted ex works in upright position with 24V voltage supply.
Through contamination, ageing or extreme climatic conditions the need for
readjustment may arise.
Readjustment on atmosphere or zero pressure is done digitally by means of the
adjust button ("adj"). The transducer will notice automatically which adjustment
point is relevant.
To achieve optimum results of the adjustment we recommend
to consider a warm-up of at least 5 minutes at the appropriate
calibration pressure before any adjustment.
I
out
(mA) = (2/175) x p(mbar) + 4.0
p (mbar) = (I
out
(mA) - 4.0) x (175/2)