Download TP01 Manual version 1509

Hukseflux Thermal Sensors
9 Electrical connection of TP01
In order to operate, TP01 should be connected to a
measurement and control system as described in the previous
chapter. A typical connection is shown in figure 9.1. For the
purpose of making a correct measurement of the heater power,
Q, there is a 4-wire connection to the heater. Two wires carry
the current, the others are used for the measurement. Through
these wires there is a negligible current, so that there is no
voltage drop across the wires, and the true voltage across the
heater wire is measured.
The voltage should be of the order of magnitude of 1 to 2 Volt.
Warning:
putting more than 2 volt across the heater may result in
permanent damage to the sensor. In case of supply from a
12VDC source, typically a 150 to 200 Ohm resistor must be put
in series with the TP01 heater. This is the user’s responsibility.
Figure 9.1 Typical connection of TP01. The relay serves to switch
the heater on and off. The thermopile output is connected to a
differential voltage measurement. The voltage across the heater
is also measured by a differential voltage channel.
It might be that a measurement system already has a current
channel. In this case it is not necessary to use a 4-wire
connection. It is however necessary to change the calculation of
the heater power.
TP01 Manual version 1509
page 24/45