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2.17
Temperature Detection via RTD Box
For temperature measurement you can connect a 7XV5662 RTD box with 12 temperature sensor inputs to the
interfaces RS485 (port B) or Ethernet (port A). Alternatively, you can connect up to 5 temperature sensors di-
rectly to the device via the I/O 2 extension module.
It is not possible to combine the connection of temperature sensors via the I/O 2 extension module with the
connection of an RTD box.
Applications
• In particular, the thermal status of motors, generators and transformers can thus be monitored. Rotating ma-
chines are additionally monitored for a violation of the bearing temperature thresholds. The temperatures
are measured by temperature sensors (RTD = Resistance Temperature Detector) in different locations of
the protected object and forwarded to the device via a 7XV5662 RTD box or via the I/O 2 extension module.
2.17.1
Description
Temperature Measurement using RTD Boxes
The RTD box determines the temperature of each measuring point from the resistance value of the temperature
detectors (Pt 100, Ni 100 or Ni 120) connected via two- or three-wire cable and converts it into a digital value.
The digital values are held available at the corresponding port (RS485 or Ethernet as ordered).
Note
Although this is not recommended by the manufacturer, you can connect Ni 100 or Ni 120 temperature sensors
to the RTD box. But you have to bear in mind that the values have to be converted in the protection device. The
values displayed at the RTD box are not correct when using Ni 100 or Ni 120 temperature sensors.
Communication with the Protection Device
The 7XV5662 RTD box can be connected to the protection device either via RS485 (port B) or Ethernet (port
A). The RTD box is an external device that is mounted on a DIN rail. It has 12 temperature inputs.
Therefore, up to 12 temperature measuring points are available in this way. For greater distances to the pro-
tection device the communication via fiber optic cables is recommended. Alternative communication structures
are shown in Appendix A.3.
Note
You can connect one RTD box either via RS485 (port B) or Ethernet (port A). Combining both connection types
is not possible.
Temperature Detection via the I/O 2 Extension Module
Up to 5 temperature sensors (Pt100, Ni 100 or Ni 120) can be connected to the 7SK80 via the I/O 2 extension
module. Use a shielded three-wire cable to make the connection. The temperature at the corresponding mea-
suring points is determined via the internal measuring function. The calculation is analogous to the RTD box.
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A5, Release date 11.2012
2.17 Temperature Detection via RTD Box
Functions
245
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