Functions
2.46 Temperature Detection by Thermoboxes
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
316
2.46 Temperature Detection by Thermoboxes
Up to two RTD boxes with a total of 12 measuring points can be used for temperature detection and evaluated
by the protection device. In particular they enable the thermal status of motors, generators and transformers to
be monitored. Rotating machines are additionally monitored for a violation of bearing temperature thresholds.
The temperatures are measured in different locations of the protected object by temperature sensors (RTD =
Resistance Temperature Detector) and are transmitted to the device via one or two 7XV566 RTD boxes.
2.46.1 Functional Description
Interaction with the Overload Protection
The ambient or coolant temperature can be fed via the thermobox to the overload protection function of the
device. For this purpose the required temperature sensor must be connected to sensor input 1 of the 1st RTD
box (corresponds to RTD 1).
RTD Box 7XV56
The 7XV566 RTD box is an external device mounted on a standard DIN rail. It features 6 temperature inputs
and one RS 485 interface for communication with the protection device. The RTD box detects the coolant tem-
perature of each measuring point from the resistance value of the temperature detectors (Pt 100, Ni 100 or Ni
120) connected with a two- or three-wire line and converts it to a digital value. The digital values are made avail-
able at a serial port.
Communication with the Protection Device
The protection device can communicate with up to 2 RTD boxes via its service port (port C or D).
Up to 12 temperature measuring points are in this way available. For greater distances to the protection device,
a fibre optic link is recommended. Possible communication structures are shown in the appendix.
Temperature Evaluation
The transmitted temperature raw data is converted to a temperature in degrees Celsius or Fahrenheit. The con-
version depends on the temperature sensor used.
For each measuring point two thresholds decisions can be performed which are available for further process-
ing. The user can allocate the pickup signals in the configuration matrix as required.
To each temperature detector is assigned an alarm which is issued in case of a short-circuit or an interruption
of the sensor circuit.
The following figure shows the logic diagram for temperature processing.
The manual supplied with the RTD box contains a diagram and dimensioned drawing.
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