User Manual

Sensors Pt100
Resistance range approx. 70 .. 167 Ohms (according to - 75.0 ... 175.0 °C),
measuring current approx.. 2.0 mA
pt1000
Resistance range ca. 700 .. 1670 Ohms (according to - 75.0 ... 175.0 °C),
measuring current approx. 0.2 mA
Special
Resistance range and measuring current according to customized configuration
Wiring of a 3-wire sensor
The measuring principle is standard 3-wire technique, that is the wire resistance and its changes within
reasonable limits does not affect the measuring. Wiring see above
Wiring of a 2-wire sensor
For 2-wire sensors the GND has to be linked with the negative input terminal. The wire resistance will not be
compensated, this leads to the following errors:
- permanent shift as a function of the wire resistance resulting a higher temperature reading
- variable error as a function of the temperature change of the cable environment with its temperature
coefficient
Wiring of a 4-wire sensor
For 4-wire sensors one lead may not be connected in order to maintain the resistance constant in the forth
and back wire. The prinicple corresponds to a 3-wire system. It should be cut off to avoid picking up noise.
The shielding is for all versions optional, its necessity depends on the conditions of the equipment:
Lead length of the sensor > 1m Shielding recommended in general
pt1000 Shielding recommended in general
Noise occurs, reading disturbed Shielding is necessary
The maximum length of the sensor leads is limited by the resistance of max. 10 Ohms at 25°C for one leg.
Dissimilar leads cause measuring errors (e.g. different wire diameters or materials).
Sensor leads with larger cross section than 0.5 mm2 or 0.75 mm2 lower the error influences.
CoolTronic GmbH Operation Manual Peltier Controller TC2812 Page 3 / 16
Revision: 1.15, Date: 30. Januar 2008 20080130_TC2812_MAN_E