5. Channel setup
Operation Manual Version 1.6
34
5.2.3. ICP
The ICP mode should be selected by use of ICP sensors. (Different sensor manufacturers introduced ICP sensors
under various aliases, including Isotron®, DeltaTron®, LIVM®, CCLD®, ACOtron®, Constant Current, CCM, and
now, IEPE. ICP
© is trademark from PCB piezotronics
, DeltaTron
© is trademark from B&K
). The principal of ICP is, a sensor will be
supplied by constant current (standard 4mA) and voltage change is the measurement signal. The correct coupling
for those sensors is „Differential Ended 3Hz High Pass Filter“ and is selected by default.
Coupling
ODU-Pin
Description
Differential Ended 3Hz High Pass Filter
Pin 3
Pin 2
Input +
Input -
Differential Ended DC
*
Pin 3
Pin 2
Input +
Input -
* In seldom cases „Differential Ended DC“ makes sense, if a
quasi static sensor signal needs to be observed. In such a
case the sensor signal has an offset and you should not
select a to small measurement range.
The current supply is done over pin 3 and 2. That means two
lines for signal and power supply together is enough. No
other pins are required.
The value of current can be individual selected for every
channel. F.e. a higher current value can be required, if the
cable between sensor and LTT500 is very long. The context
menu enables a selection between 0.5mA and 10mA.
5.2.4. Strain-Gauge Current
DMS Current is a Strain-Gauge (short DMS:
DehnungsMessStreifen, German) input in full bridge with
constant current supply for the sensor elements. The
detailed explanation follows in Strain-Gauge fullbridge
chapter. The only difference is the supply with constant
current.
