• Gossen Metrawatt
  • Camille Bauer

LA106: How is overvoltage protection technically implemented in the Konstanter?

A comparator, which is independent of the voltage monitor (sense amplifier) and the voltage regulator, monitors voltage applied to the output terminals and compares it with the selected trigger value, which is in turn generated by a separate D-A converter with its own reference voltage. If output voltage exceeds the trigger value, an OUTPUT ON OFF procedure is started by the processor (with temporary activation of the sink function in order to quickly discharge the output capacitor), and the cycle for the power transformer is disabled from a hardware standpoint, so that no further energy transfer is possible.

Triggered overvoltage protection is reset and the output is reactivated by means of OUTPUT OFF ON. Response time for overvoltage protection is adjustable, but it amounts to no more than 200 µs.

If overvoltage protection has been correctly selected, it protects connected power consumers against high voltage resulting from:

 

  • Inadvertent, excessively high voltage settings
    • In the case of manual operation
    • In the case of computer control
    • In the case of control by means of an external analog signal
       
  • Inadvertent polarity reversal of the sensing leads
     
  • Incorrect switching sequences for the output and sensing leads by means of relays with active output (correct sequence: first switch on output leads followed by sensing leads, first switch off sensing leads followed by output leads).
     
  • Device malfunction or defect
    Overvoltage protection does not protect the device from defects resulting from the application of unipolar voltages to the output terminals, which exceed the specified value for voltage feedback strength.

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