omnigrad T TR24
2
Hauser
Function and system design
Measuring principle
In the RTD (Resistance Temperature Detector) thermometers, the sensing element consists of an electrical
resistance with value of 100 Ohm at 0°C (called Pt 100, in compliance with standard DIN EN 60751) which
increases at higher temperatures according to a coefficient characteristic of the resistor material (platinum).
In industrial thermometers that comply with the DIN EN 60751 standard, the value of this coefficient is
α
= 3.85*10
-3
°C
-1
, calculated between 0 and 100°C.
Equipment architecture
The Omnigrad T TR 25 temperature sensor is made up of a measurement probe and a housing (head), which
may contain a transmitter or the terminals on the ceramic block for electrical connection.
The sensor is manufactured according to standards DIN 43729 (housing) and 43735 (probe) and can therefore
guarantee a good adaptability to the most common industrial processes. The measurement probe consists of a
(replaceable) insert in mineral oxide with a diameter of 3 or 6 mm. The TR 25 can be fitted onto the plant (tube
or vessel) by means of a threaded root fitted below the head, which can be chosen from the most common
models (see section "Structure of the components"). The electrical structure of the thermometer always com-
plies with DIN EN 60751 standard rules. The sensing element is available in two versions with a thin film (TF)
or wire wound (WW), the latter with a large measuring and accuracy range.
The housing can be of different types and materials (plastic, painted aluminium alloy, stainless steel). The way
in which it fits to probe and the cable gland ensure a minimum grade of IP65 (Ingress Protection).
Fig. 1:
TR 25
with the various types of heads, process connections and end parts of the probe
Material
• Wetted parts in SS 316L/1.0004
Weight
From 0.5 to 2 kg for standard options.
Electronics
The required type of output signal can be obtained by choosing the correct head-mounted transmitter.
Hauser supplies "state-of-the-art" transmitters (the iTEMP
®
series) built in 2-wire technology and
with 4…20 mA output signal, HART
®
or PROFIBUS-PA
®
. All of the transmitters can be easily programmed
using a personal computer through the ReadWin
®
2000 and FieldCare public domain softwares (for transmit-
ters 4…20 mA and HART
®
) or the CommuWin II software (for PROFIBUS-PA
®
transmitters). The HART
®
transmitters can also be programmed with the hand-held operating module DXR 275 (Universal HART
®
Com-
municator). A PCP (4…20 mA, TMT 180) model with enhanced accuracy is available. In the case of PROFI-
BUS-PA
®
transmitters, E+H recommends the use of PROFIBUS
®
dedicated connectors. The Weidmüller type
(Pg 13.5 - M12) is provided as a standard option. For detailed information about transmitters, please refer to
the relevant documentation (refer to the TI codes at the end of the document).
If a head-mounted transmitter is not employed, the sensor probe can be connected through the
terminal block to a remote converter (i.e. DIN rail transmitter).
