Page 16 - Wagp_InterfaceElectronic_Volume4_2015_US.pdf

0 WAGO Analog Signal Conditioning Modules

14
Signal Conditioners for measurement Temperature Signal Conditioners WAGO analog signal conditioning
technology modules are designed to work with com-
The Recording and processing of num- Temperature sensing in the process mon types of “J” (Iron/Constantan) and
bers of physical values, such as tempera- industry is traditionally performed via “K” (Chromel/Alumel) thermocouples,
ture, pressure, speed, humidity, etc., form “Thermocouple” or “RTD” (Platinum Resi- which comply with IEC standard 60584
the basis for modern process control. stance) elements. A popular RTD is the Pt. 1, with cold junction compen sation.
Special sensors supply these values as Pt100 element. Having a nominal resi- WAGO temperature transducers are
analog signals, which must be transmit- stance of 100 ohm at 0°C, and a typical available with industry standard output
ted as standard analog signals to the operating temperature range of –200°C signals of 0-10 V, 0-20 mA or 4-20 mA.
processing instruments. These analog to + 650°C, its non-linear characteri-
signals may be transmitted over long stics are compensated by the WAGO
or short distances between sensors and signal conditioning module, as the Pt100
controlling mechanisms, for example PLCs element typically meets the IEC 60571 Additionally, they have an integral wire
and computers, or in less sophisticated specification. break/short circuit detection. Visual
systems directly to relays or actuators. The WAGO Pt100 signal conditioning LED fault indication is standard, but the
Various standards are used. Normally module is suitable for 2- or 3-wire RTD, WAGO modules also include an error
recognized signals are with 3-wire RTDs offering greater accura- output signal that may be used to initiate
0-10 V, 0-20 mA and 4-20 mA. cy over longer distances. Thermocouples a safe shutdown before serious damage
consist of two different metals that are occurs in the event of a wire break or
connected at the measuring point and short circuit of the measuring sensor.
The transducer/transmitter may also linea utilize of the “Dissimilar Metal (EMF)
rize non-linear signals internally, before effect”, which can be measured at the
transmission. In order to prevent these open ends of an element. For this purpose, a transistor switches the
relatively low power signals from dis output as soon as the operating voltage
tortion, WAGO AUTOMATION offers a is correct and no error is present in the
complete range of modules for measure- measuring circuit on VB-2V. The transistor
ment and transmission of these signals, blocks the output in the case of an error.
both with and without isolation between WAGO temperature transducers are
the module’s input/output and the sup- available as follows:
ply voltage (if necessary). Apart from
the converters for various standardized • The “wire break” and “short circuit”
signals, WAGO offers a complete selec- error output is available on the
tion of analog/digital and digital/analog Pt100 module.
converters with a resolution of 10 bits. • The “wire break” function is available-
on the J and K Thermocouple modules.
In the event of wire break, the outputs
1 + 24V
switch to the following values:
OUT
2 ERR. Output Value
0V 0V 0(4)-20mA ≥20.5mA
0-10V ≥14V
With Pt100 modules, and in case of
short circuit, the outputs switch
to 0V or 0mA, respectively.
– When using insulated thermocouples, terminal “2”
has to be connected to 0 V.
– In the case of grounded (earthed) thermo couples,
the design is such that terminal 2 is alread connec-
ted to 0 V inside the thermo couple element.
Therefore, it is not necessary to jumper 2 → 0 V.
– For commoning 2 → 0 V, 4-wire base terminals are
The electronics are protectect by an recommended.
enclosure which can be snapped on a
®
DIN 35 rail. The CAGE CLAMP connec-
tion ensures a secure, maintenance-free
connection for conductors sized from
2
2
0.08 mm to 2.5 mm /AWG 28-12.
The mechanical assemble of pluggable
modules for rail-mounted terminal blocks
on DIN 35 rails offers all the advantages
®
of CAGE CLAMP connectivity.
Additionally, the separation of wiring and
function levels offer maximum flexibility
and ease of service.