UC2854/3855 based PFC Production Testing Questions

Working on a project to improving the data gathering and the test process for a 1kw UC3855 PFC and a 2kW UC2854 based PFC. The units are

100-260input 50-60Hz and boost to 400VDC. Approximately a combined 10pcs per day are tested. The intent of the data gathered in to monitor the yield.

The test stand is not automated with a tech controlling a variable DC supply and a VARIAC. The test is sectioned into DC input tests and AC input tests. The stand has scope with current & voltage probe, input/output power meter.

I am having a hard time trying to determine what would be useful data to the indicate PFCs are "in control". I do not want to go crazy and gather data for the sake of having data.

What are good parameters to collect to indicate PFC are functioning ? PFC?

Ideally the data could be presented on control charts and basic SPC concepts could be applied.

Thanks for any responses

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With a fixed output load, just monitor input power, nothing else. If it changes by more than +/-3%, you have problem. Cheers, Harry

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Harry Dellamano

Oops, if the power input changes >+/-3% from unit to unit, then you have a problem. Test one known good (Gold) unit and compare the rest to it. Always use same test setup. Harry

Reply to
Harry Dellamano

You might also want to consider start-up confirmation at the line and load extremes. Randomized order of testing advized for this.

Manual testing on a production line should be considered as cruel and unusual punishment, unless it is accompanied by beaverish background activity to automate asap.


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Thanks for the responses.

We test the low line:light load, low line:heavy load, High line: light load, high line:heavy load. The load is just a bank of ohmite wirewounds resistors with manual switches to put more resistors in our out of the circuit. Really rough setup.

Using one big resistor and a high current FET at different duty cycles might work. Got any suggested readings that might help me set this up

WHat line load combination would be the most telling to indicate that PFC is working well? Seem like low line: heavy load as this is the highest current position.

Thanks G

legg wrote:

units are






functioning ?


If it

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I'm not sure that the production line is the place to determine this. They are concerned only with defect detection, there.

Randomized order of start-up conditions is only an iffy way of checking for batch integrity. A single problem suggests that the entire batch be reviewed.

Tests simulating cold start are the most difficult to configure, with no residual charges remaining in the circuitry, due to time limitations - hence randomization. Only effective if not recently pre-energized.

Input power measurements are also only indicators - highly temperature and test condition dependant. They are more reliable after burn-in, when electrolytics have reformed, or other weaknesses have become evident.


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