Measuring Accessories; Md 200 And Md 200A Differential High Voltage Probes - Ametek Teseq NSG 3060 User Manual

14.6 Measuring accessories

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14.6.1 MD 200 and MD 200A differential high voltage probes

The Teseq MD 200 and MD 200A high voltage differential probes are ideally
suited to allow EMC engineers to verify their conducted EMC test generators
periodically. Their performance permits to be used for many other purposes
where higher voltages have to be measured in a potential free manner.
Annual calibration and periodic verification
The annual calibration of test equipment recommended by most of the quality
systems (ISO 9000, ISO 17025, etc.) has to be considered as a validation of all
measurements done since the last calibration.
Many EMC standards call for a verification of the test equipment before and
after every test session. If the verification shows differing results, no valid test
results can be assumed and the test equipment has to be re-calibrated. It is
therefore highly recommended that the EMC test engineer periodically verifies
his test equipment in order to ensure good functionality and accuracy.
Periodic verification can be done before a test session or once a day or week
or month; it is up to the user to decide. Only a few points need to be checked,
which will take only a few minutes if the right test equipment is available.
Potential free (differential) measurements
Since it may be useful to measure pulses superimposed on the mains for peri-
odic verification purposes, it is essential to work with differential measurements.
Using classic non-differential probes and connecting with reversed polarity will
result in the oscilloscope chassis being connected to the mains. In the best
case a circuit breaker will trip, in the worst case, for example if the oscilloscope
is battery powered or supplied via an isolation transformer, the oscilloscope
chassis will be at a voltage equal to mains voltage plus the peak pulse voltage,
which could be lethal for the user. The Teseq high voltage differential probe MD
200 series is ideally suited to measure all kinds of EMI pulses in the microsecond
range, industrial, telecom and automotive surges as well as power line dips,
interrupts and distortions.
NSG 3060 EMC test system