YSI IQ SensorNet 2020 XT Terminal - Manual (Page 36)

Installation System 2020 XT USB
3 - 6 ba76019e01 12/2012
3.4.3 Effect of the cable length
The length of the cables in the IQ S ENSOR N ET affects
 the operating voltage available for a component
 the quality of data transmission.
Note
All information applies to SNCIQ cable material only. As regards the
copper wire diameter and dielectric, this cable is especially designed
for the combined energy and data transmission via great distances and
ensures the lightning protection characteristics stated in chapter 8
T
ECHNICAL DATA .
Voltage drop due to
cable lengths
Very long cables in the IQ S ENSOR N ET cause voltage drops with
growing distance from the power supply module. If the voltage is under
the limit values, further IQ power supply modules must be used to
compensate.
Guideline If the power supply modules are positioned in the vicinity of the main
consumers and the total cable length is no more than 400 m, no
additional cable losses have normally to be taken into account. Main
consumers are components with a power consumption of 5 W or more.
Note
When determining the number of power supply modules required, the
most unfavorable design has to be taken into account for mobile
components (Terminals). I. e., take into account
 the maximum number of mobile components and
 their greatest possible installation distance from the power supply
module.
Determining the length
of the cable section
A diagram is used to determine whether an additional MIQ power
supply module is necessary for the planned installation. To do so, the
length of the cable section must be determined.
A cable section is the longest continuous length of cable from an
MIQ power supply module to a consumer. Sensor connection
cables up to 15 m are not taken into account in this.