Analogue Signal Processing
156
Analogue Signal Processing
The problem
The real world can be measured in many
ways, for example, via temperature,
humidity, air pressure and so forth.
The parameters of these different physical
qualities change continuously. Elements
that monitor statuses and changes in sta-
tuses of a given environment, must reflect
these continual changes.
Within the framework of industrial moni-
toring tasks, the statuses of an environ-
ment are monitored by using sensors.
These sensors should provide signals that
enable connected evaluating and monitor-
ing installations to draw detailed conclu-
sions concerning the status of, for exam-
ple, a production process. The sensor sig-
nals trace the continuous changes in the
monitored range. The signals can be in
analogue or digital form; which means in
normal cases, an electrical voltage or cur-
rent value is produced that corresponds
proportionally to the monitored physical
quantities. Increasing automation with the
intention of achieving or maintaining cer-
tain predetermined statuses makes the
processing of analogue values increasingly
important. This is also true of fields
beyond those where this has been neces-
sary and standard for a long time, for
example, processing technology in the
chemical industry. Standard electrical
signal values are the norm within the
framework of this
processing technology.
Current values from 0...20
mA, 4...20 mA or voltage
values from 0...10 V have
been introduced as
sensor output values for
differing physical
quantities. Weidmüller has
taken account the need
for increasing automation
with the processing of
these analogue signals,
and offers a wide range
of products that are
designed for handling
sensor signals.
This means, units are
made available for
standard signals (0...20
mA, 4...20 mA, 0...10 V)
that generate output
signal values proportional
to the variable input
signals, and at the same
time enable the safe
separation of, for
example, sensor circuits
of an evaluation circuit.
This safe separation is
particularly important to avoid mutual
interference of multiple sensor circuits,
for example, ground loops in interlinked
measurement circuits. The wide range of
products includes all functions for
converting separation and monitoring
signals. The different designs in
connection with the respective functions
cover practically all applications in
industrial measurement technology.
With these new products, Weidmüller
offers the possibility of taking into account
the demands of modern automation
technology with the inclusion of analogue
signals. These products guarantee an
elementary function between signals from
the field and the further processing
systems. The mechanical characteristics
of these products correspond to those of
the well-known Weidmüller products and
are part of a continuous, ongoing
concept. The signal conditioners can be
combined together with other Weidmüller
products.
They have been electrically and
mechanically designed to ensure that only
a minimum of wiring and maintenance
costs are necessary.
The product program
contains the following functions:
Current transformer
Voltage transformer
Thermocouple conditioners for
resistance thermometers
Frequency signal conditioner
Potentiometer conditioner
AC signal conditioner
Bridge measurement conditioner
Limit value monitoring modules
AD/DA converter
These products are categorised according
to functionality as pure signal conversion,
2-way-isolation, 3-way-isolation and as
passive separation.
157
Analogue Signal
Processing
Analogue Signal Processing
2-way-isolation
separates the signals galvanically and decouples the measurement
circuits. In so doing it eliminates potential differences caused by long cable lengths and
common reference points. Furthermore, the galvanic isolation offers protection against
destruction by overvoltage, and against inductive and capacitive interferences.
3-way-isolation
also decouples the supply voltage from the input and output circuits,
and enables the function with only one operating voltage.
The
passive isolator
offers a further elementary advantage; it needs no additional volt-
age supply. The supply to the modules ensues via the input circuit and is the trans-
ferred to the output. This current loop supply is distinguished by very low power con-
sumption.
There are a large number of products available for measuring temperatures. RTD
PT100
signals, in 2-, 3- and 4-wire technology, are converted to standardised 0 – 20
mA, 4 – 20 mA and 0 – 10 V signals.
The modules which can be connected to commercially available
thermocouples
have
cold junction compensation as standard. Furthermore, the modules amplify and linea-
rize the voltage signals from the thermocouple. This guarantees an exact conditioning
of analogue signals by eliminating sources of interference and errors.
Frequency converters
convert frequencies to standard analogue signals. This
enables controllers connected in series to directly process impulse trains when making
speed or rotational speed measurements.
It is inconceivable to think about automation without
analogue-digital-analogue
converters.
To bring together the aforementioned analogue form of describing the envi-
ronment and the customary digital processing, within the framework of process moni-
toring, it is necessary to convert analogue signals into digital signals. Weidmüller offers
modules for the following standard input and output signals: 0...20 mA, 4...20 mA and
0...10 V. 8-bit and 12-bit digital modules are available. All modules have an added input
for making instantaneous measurements.
Current monitoring modules
enable the monitoring of current values up to 60 A in
alternating or direct voltages. Over range or under range values trip the switching out-
put. Modules with analogue outputs enable the continuous monitoring of currents via
connected controls.
Voltage monitoring modules
can be used to monitor direct and alternating voltages.
Voltage fluctuations, resulting from switching operations or network overloads, can be
reliably recognised and reported via the adjustable threshold function.
Modules for
monitoring of revolutions and torque
enable the control of cyclic move-
ments on conveyor belts, ventilators and pumps. The output responds after a set
amount of time, should the expected impulse not be received. The reliable potential-
free relay contact, signalises the interference to the responsible component group.
158
Design Overview
Mini Coupler / Mini Conditioner
DK Mini Coupler / MCZ Mini Conditioner
Extensive range of electronic functions
in terminal format
Pluggable cross-connections with
mini conditioners
Mini couplers with screw-in
cross-connection combs
Mini couplers with screw
connections
Mini conditioners with tension
clamp connections
WAVESERIES
WAVE
ANALOG
/ WAVE
ANALOG
PRO / WAVE
CONTROL
Pluggable PCB for fast service when
the configuration is changed
Pluggable cross-connection in base socket
housing to distribute the power supply,
marking (CC) in the block diagram on
the head plate
Pluggable connections with optional
screw or tension clamp connection
RS profiles
Analog-/Digital-Converters
Mounts onto TS 32 and TS 35 mounting rails
Open, cost-saving design
Variable housing width
Analogue Signal
Processing
159
Selection Table of Functions
Function
DC signal conditioners
Areas of application
Signal conditioning, signal isolation,
suppression of mass loops
Description
DC input/fixed functions
and configurable inputs and
outputs
DC input/limit value
monitoring
Versions
MCZ
WAVE
ANALOG
WAVE
ANALOG
PRO
DK
MCZ
Page
164
174-184
185
172
173
Motor current limitation, pressure
alarm, direct disconnection of
connected modules, safety function
PT100 signal conditioners
Temperature monitoring, noise rejec-
tion, electrical decoupling of visualiza-
tion devices, suppression of mass
loops, heating and cooling monitoring,
overheating protection of motors
RTD input/fixed functions
and configurable inputs and
outputs
MCZ
WAVE
ANALOG
WAVE
ANALOG
PRO
165
186-188
189
Thermocouple conditioners
Temperature monitoring, noise rejec-
tion, electrical decoupling of visualiza-
tion devices, suppression of mass
loops, heating and cooling monitoring,
overheating protection of motors
Thermo input/fixed functions
and configurable inputs and
outputs
WAVE
ANALOG
WAVE
ANALOG
PRO
190
191
Frequency signal conditioners
Flow rate measurements, frequency
converter monitoring, speed measure-
ments, pulse processing
Conditioning of voltage and current
signals in 8-bit/12-bit digital form
Motor current monitoring,
emergency lighting monitoring
Input/fixed functions and
configurable inputs and
outputs
8-bit AD/DA converter
12-bit AD/DA converter
AC input/measuring of
sinusoidal and non sinusoidal
signals up to 60A
One and three-phase
overvoltage
PNP/NPN or NAMUR
input/switching output
DK
MCZ
167-168
166
AD/DA converters
RS
210-213
Current monitoring
DKI
WAVE
CONTROL
SMSI
SMSU
172
196-199
200-203
204-205
Voltage monitoring
Under and overvoltage monitoring,
operating status indication
Downtime monitoring, conveyor-drive
monitoring, monitoring of fans, pumps
or pistons
Switching amplifier
Testing measuring distances, defined
input of analogue values
Motion and rotational
speed monitoring
DKLW
SMS
169
206
Namur switching amplifier
Setpoint device
Namur input/switching output
1 control input/+/-set value/
analogue output
EGV
EMA/SW24
207
208
160
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