I need to measure the harmonic distortion on a solar inverter (power output). I need to buy all the equipment from scratch and was wondering if my DSO needs to be CAT 2 rated if I use a CAT2 10x probe.

The mains output will be Grid tied and be at 230V 50Hz.

The DSO should only see 35V.

Alternatively, could I "just" use a AC transformer to reduce the voltage down to a lower more manageable level? As I understand, the harmonics should be higher frequency, so should have better flux linkage in a transformer, so should be measurable on the transformer secondary (given a ohmic load eg 10MOhm DSO)?


Short Answer: if Probe alone is designed for this and it meets these specs and will work.

This specification informs the user this module is rated for 300V CAT II and 600V CAT I. In other words, this module can withstand up to 2,500V impulse voltage. This specification additionally informs the user this module must not be connected to MAINs CAT II circuits when operated above 300V. Lastly, the user should not use this module with Category III or IV circuits.

Locate IEC 61010-1 2nd Edition UL 61010B-1 (UL 31111-1) for more details.

It assumed the tech is aware that the probe tip/ring is clean and dry and surge flash can occur if transients beyond this rating might be possible in lightning prone areas.

  • \$\begingroup\$ Sorry you lost me, do both the DSO and the probe need to be CAT2?? \$\endgroup\$ – Aron Sep 27 '18 at 23:12
  • \$\begingroup\$ just the probe..... \$\endgroup\$ – Sunnyskyguy EE75 Sep 27 '18 at 23:34
  • 1
    \$\begingroup\$ who marked it -1 ought to be professional enough to explain why or suggest improvements. Otherwise zero valued added contributor \$\endgroup\$ – Sunnyskyguy EE75 Sep 28 '18 at 13:29

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