Printed in the Federal Republic of Germany
TR-Electronic GmbH 2012, All Rights Reserved
05/30/2018
TR - ECE - BA - GB - 0095 - 19
Page 27 of 56
4.5.2 Optional HTL-Level, 13…27 VDC
Optionally, the incremental interface is also available with HTL levels. For technical
reasons, the user has to take the following general conditions into account with this
version: ambient temperature, cable length, cable capacitance, supply voltage, and
output frequency.
In this case, the maximum output frequencies that can be reached via the incremental
interface are a function of the cable capacitance, the supply voltage and the ambient
temperature. Therefore, the use of this interface is reasonable only if the interface
characteristics meet the technical requirements.
From the view of the measuring system, the transmission cable represents a
capacitive load which must be reloaded with each impulse. The load quantity required
varies strongly depending on the cable capacitance. It is this reloading of the cable
capacitances that is responsible for the high power dissipation and heat, which result
in the measuring system.
Assuming a cable length (75 pF/m) of 100 m, with half the limit frequency being
associated with the rated voltage of 24 VDC, the current consumption of the
measuring system is twice as high.
Due to the developing heat, the measuring system may only be operated with approx.
80 % of the working temperature specified.
The following diagram shows the different dependencies with respect to three different
supply voltages.
Fixed variables are
•
Cable capacitance: 75 pF/m
•
Ambient temperature: 40 °C and 70 °C
Figure 5: Cable lengths / Limiting frequencies
Other cable parameters, frequencies and ambient temperatures as well as bearing
heat and temperature increase via the shaft and flange, can yield a considerably
poorer result in practice.
Therefore, the fault-free function of the incremental interface with the application-
dependent parameters has to be checked prior to productive operation.
