Brochure/Catalogue

Load / Load Resistor
• The load is a load resistor on the output side of a
measuring transducer or isolating amplier. The load is
usually less than 500 Ω at the current outputs. Voltage
outputs are normally under a load greater than 1 KΩ.
Peak value
Root mean
square value
Galvanic Isolation / Safe Separation
• Galvanic isolation is understood to mean an electrical
isolation between the input and output circuit and the
circuit‘s supply voltage. It can be set up either optically
using an opto coupler or with a transformer. The isolation
serves to safeguard the measuring circuit against damage
and to eliminate ground loops, which could cause the
measured signal to be corrupted.
• Safe separation is specied under the German
DIN VDE 0106 Section 101 standard. This fundamental
safety standard is intended to safeguard persons against
hazardous body currents and describes the basic
requirements for safe separation in electrical operating
equipment. Thus, for instance, the voltage supply of
50 V AC/ 75 V DC as under 50178 may not be exceeded.
If this voltage is exceeded a reinforced or double insulated
and thus an increase in the clearance and creepage
distances is stipulated.
Cut-off Frequency
• Cut-off frequencies indicate the dynamic transfer
characteristic of an isolation amplier.
• The given frequency is the (-3dB-) limit, at which a distinct
change occurs to the signal.
• An increased cut-off frequency leads to a transmission of
higher-frequency alternating components, which corrupts
the required signal.
Hysteresis
• Hysteresis indicates the percentage difference between
the input and output points of a switching contact.
It should not be lower than a given minimum value,
as otherwise a specied chase can no longer be
implemented.
Broken-wire Detection
• When measuring transformers with broken wire detection
the input signal is monitored permanently. In the event of
a fault (broken wire) the output signal exceeds its rated
range. The downstream control circuit can then analyse
the fault case.
Response Time
• Response time refers to the change in output signal for an
input signal jump (10 … 90 %). It is directly related to the
cut-off frequency (inversely proportional).
Accuracy / Temperature Coefcient
•
Accuracy describes the capability of a measuring device to
deliver a measured value as accurately as possible. It relates
to the end value and is given for ambient temperature
(23°C). Example:
An RTD is given with an accuracy of 1 %. The measuring
range is set to 0 – 200 °C. The expected effective error of:
200*1 % = +/– 2K applies across the entire measurement
range.
• Temperature coefciency describes the deviations in
accuracy of the measuring devices dependent on the
ambient temperature. It is given as a % or in parts per
million / Kelvin (ppm /K).
Example:
An RTD with an accuracy of 1 % and a measuring range
of 0 – 200 °C has a temperature coefciency of
250 ppm / K. If the device is operated at +40 °C, it will
then contribute the following to an expected absolute
error: (([40°C – 23°C] *250ppm/K) +1%) *200K) =
+/– 2,85K across the entire measurement range.
Technical data
W
Technical appendix/Glossary
W.92729490000