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Air Purifier Electrical Fault.

I was given a faulty VAX air purifier to repair today. The fan would not turn. The motor would not work. The control buttons did operate and a confirmatory bleep could be heard when they were pressed. Also dim L.E.D.s lit up confirming that the control panel seemed to be o.k. The motor fan did rotate quite freely by hand. No damage to P.C.B. P.C.B. fuse o.k. The appliance is rated at 75 Watts. The 1.5 micro Farad motor starting capacitor was reading very low capacitance. In the pico Farad region. After replacement of the bad capacitor the motor still did not start.

What did I have to do to get the motor working, and why?

https://www.vax.co.uk/ap01-air-purifier

Z.

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0 mapj1 over 5 years ago

Indeed. An 'X' capacitor is rated to spend all day connected L-N, but is allowed to fail dead short - as the assumption is tht this trips the ADS and is safe.

A Y capacitor has a higher standard, and is intended to be between Live and the case of earthed equipment, and is very care fully designed to fail open circuit when it finally dies.

Ratings are RMS, but there is a huge margin - a 250V X2 will have been tested to survive short duration 2500V surges - the equivalent Y about twice that.
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0 mapj1 over 5 years ago

Indeed. An 'X' capacitor is rated to spend all day connected L-N, but is allowed to fail dead short - as the assumption is tht this trips the ADS and is safe.

A Y capacitor has a higher standard, and is intended to be between Live and the case of earthed equipment, and is very care fully designed to fail open circuit when it finally dies.

Ratings are RMS, but there is a huge margin - a 250V X2 will have been tested to survive short duration 2500V surges - the equivalent Y about twice that.
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Air Purifier Electrical Fault.

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