Pfaudler TW Series - 6.3 Transmitter TTH300

The TW probe is designed in four-wire
technology (2 parallel supply bands
each). Therefore, TW probes can be con-
nected in a four-wire circuit. With this
measuring method, a constant measur-
ing current flows through 2 wires, where-
as the temperature-dependent voltage
drop at the measuring resistor is mea-
sured via the remaining 2 wires. In a four-
wire circuit, the influence of the supply
conductor resistance on the measured
result is totally neutralized.
Probe carriers equipped with TW probes
can optionally be combined with the
following measuring probes made by
Pfaudler:
n Typ P Measuring probe for glass
monitoring
n Typ FT Measuring probe for capaci-
tive detection of filling limits
or interfaces between liquids
n Typ FS Measuring probe continuous,
capacitive detection of filling
levels
n Typ T Measuring probe for tem-
perature measurement using
a thermocouple
For more details about possible com-
binations, please contact the Pfaudler
Instrumentation department.
6.3 Transmitter TTH300
A transmitter of the type TTH300 made
by ABB is used as a standard for evaluat-
ing the signal measured by the TW probe.
The transmitter is a freely programmable
unit that converts the measured signals
of resistance thermometers and thermo-
couples into a standard potential-free
4-20 mA signal. The transmitter is inte-
grated into the terminal box already in
the factory where it is also connected to
the sensor lines.
As already mentioned in Sect. 6.1, the
resistance thermometer for the TW probe
cannot be produced to have a resistance
of exactly 100 Ω at 0 °C. For this reason,
the exact resistance in Ω of the resist-
ance thermometer is measured upon
completion of the TW probe. During the
internal acceptance test in the factory,
the transmitter is parameterized with the
characteristic of this Ω value. The char-
acteristic has a total of 32 intermediate
points. The values of the characteristic
are indicated in the test report that is
attached to each probe supplied.
The transmitter is programmed using the
“Smart Vision” firmware. The TTH300
is also equipped with a HART interface
which allows for programming of the
transmitter on location.
For more details concerning the trans-
mitter, please refer to the documentation
that is attached to each probe supplied.
As a rule, it is possible to use other types
or makes instead of the TTH300. How-
ever, the following conditions must be
observed in this case:
n The transmitter must be freely pro-
grammable and must be programmed
with the probe-specific characteristic.
Third-party transmitters cannot be
programmed by Pfaudler because
we do not have the hardware and
software necessary for that purpose.
However, Pfaudler will support you
with the programming of third-party
transmitters.
n Pfaudler cannot provide any binding
information concerning the accuracy
of the measuring system as a whole in
this case.
If the ambient temperature in the sur-
roundings of the terminal box is exces-
sively high on location (refer to Sect. 6.4),
the transmitter must be installed next to
the probe carrier in an area in which the
ambient temperature is lower. The 4-wire
signal lead may be used to connect the
terminal box on the probe carrier to the
transmitter.
m The TW probe must in all
cases be operated in conjunction
with a programmable transmitter,
otherwise, the temperature measure-
ment will not be correct.
Table 3 Tightening torques of glass-lined flange connections
Reactor type AE AE/BE/CE E BE/CE
Nominal reactor size 63
to
400
630
to
1000
1600
to
6300
1200
to
20000
8000
to
40000
baffle with stuffing box 1 2 2 2 2
baffle/thermowell with
flange
2 2 2 – 2
Quatro Pipe – 2 2 2 2
© Pfaudler GmbH · OI 302-8 e
12
Temperature probes type T/TW
© Pfaudler GmbH 12
Temperature probes type T/TW