Loop-powered transmitter for Pt-100 - HT1002

The HT1002 loop powered temperature transmitter for platinum probes has a basic accuracy of 0.1 %. The instrument is designed for 3-wire technology but can also be used in a 2-wire circuit. The temperature measured by the probe is linearized and converted into a signal current of 4...20 mA. The temperature range, for the 4...20 mA current signal, can be custom defined with in -200 to +600 0C.

Fine adjustment of ZERO and GAIN can be done with two 19-turn potentiometers. If any one of the three probe connections is broken, the instrument's output current will go to either its high current limit (34 mA) or low current limit (3.6 mA). The instrument can be installed in DIN sensor head model "B". The HT1002 provides an easy and elegant solution to expensive wiring costs.

Applications: Heating and air conditioning, biology, ecology, chemistry, industrial temperature controls, water resources, machinery, etc.



Technical data 

Probe element

Pt-100 platinum probe with 100 W @ 0 0C (DIN 43 760), in 2- or 3-wire connection

Probe terminals

3-wire - see label on terminal plate; 2-wire - probe at terminals 1+2, bridge between 2+3

Signal output

4...20 mA for any range between -200 and +600 0C

Supply voltage

11...33 VDC

Max. power dissipation

1.2 W


+/- 0.1 % @ 23 0C ambient temperature within the range of -50...+500 0C


Better than 0.1 %

Signal current output

Zero drift - typical 60 ppM / 0C; gain drift - typical 56 ppM / 0C

Long-term stability

0.15 % after 3 months

Working temperature range

-20...60 0C

Max. humidity

95 %, non-condensing

Max. lead length sensor wires

2,000 m two wires


1100 W max. @ 33 VDC, 560 W typical @ 24 VDC



Zero / Gain adjustment

Zero and Gain fine adjustment can be done by two potentiometers. This adjustment can only be used for line adjustments and not to change the measuring range.


According to DIN 43760, +/- 0.1 %