SCB20
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9.4.1 Protection
The power amplifiers are protected against short circuits (limiting the output current) and over
temperature. Additionally, the current sources are shut down if one of the measured currents
exceeds the operating values or if the consistency check fails (e. g. if it is not possible to
reach the aimed current value).
These two measures protect the SCB20 against short circuits and/or mismatched
connections.
9.4.2 Measurements Provided for Diagnostic
In the following section, there is a list of possible diagnostic functions that can be invoked by
SSRB commands. According to the results of the measurements the software running on the
ELCB may notify the user about abnormal events.
Status/Errors
The SCB20 can perform the following checks:
• Power voltages OK.
• Short circuits/disconnected lines at the current source output.
• Current source status (operational or shut down).
• Heat sink over temperature.
Output Measurements
Both, the current and the voltage of each current source output can be retrieved over the
SSRB. Additionally, the voltage after the integrator stage (U Int) can be measured for each
channel. This feature provides additional information about the connected load and could
potentially be used for identification.
Temperature Measurement
There is a PT100 resistor built in the shim tube providing temperature measurement. It is
therefore possible to read the shim tube temperature over the SSRB bus for diagnostic
purpose. If the shim tube temperature exceeds a given limit then the current sources are shut
down.
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General