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I am doing pre-compliance EMC testing on an electric generator. The standard I am reading explains how to test devices that get power from mains, but it doesn't explain the testing procedure for a power supply/generator. My idea is to put a constant load on the generator and use a current probe hooked up to a spectrum analyzer to see if there are any noteworthy peaks in frequency.

Specific questions:

  1. Would using a constant load/current probe be sufficient for testing all frequencies?
  2. Is there a need for a LISN when testing a generator for conducted emissions?
  3. Are there any online sources for procedural EMC testing of generators/power supplies? (I have googled many iterations to no avail.)
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Would using a constant load/current probe be sufficient for testing all frequencies?

Is there a need for a LISN when testing a generator for conducted emissions?

Probably not, but only if your load is constant and doesn't create noise. Since an LISN is a filter used to block mains noise from your measurement, a current probe would probably suffice. But I'd imagine they'll use an LISN at the ETL, replicating their test setup would be best.

Are there any online sources for procedural EMC testing of generators/power supplies? (I have googled many iterations to no avail.)

As far as I can tell, there aren't any direct requirements for generators as far as IEC requirements go. There will be saftey requirements. On most generators that I have seen an ETL sticker cannot be found on the outside or in the operators manual. Work with your product testing lab to see what you need or find a consultant.

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  • \$\begingroup\$ This surprises me. I would think that generators would be held to some sort of standard as far as allowable emission levels on the output lines. Am I misunderstanding the intent of conducted emissions testing? \$\endgroup\$
    – cemanuel
    Jul 31, 2018 at 18:52
  • \$\begingroup\$ Electrical conducted emissions testing is to prevent noise from affecting other devices (like an SMPS affecting a TV through mains AC). Since generators are probably pretty noisy, and the voltage not as regulated as the grid (it's tied to the motor and they routinely run out of gas), and a large number of devices are not plugged into them, its my guess that they are not held up to the same standard. \$\endgroup\$
    – Voltage Spike ♦
    Jul 31, 2018 at 18:55
  • \$\begingroup\$ Normally the IEC reqirements and testing are posted in the manual, I couldn't find any with tested IEC requirements, or even a mention of an ETL test. \$\endgroup\$
    – Voltage Spike ♦
    Jul 31, 2018 at 18:57

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