Re: OT: Sunon SP100A 115V fan (0.26A) in a 240V unit


I wanted to do the same thing to limit the power output of a transformer. The problem is for all the useful power limiting values of capacitance, transformer inductance resonates with it near the power frequency. This is due to the fact that both the inductance and capacitance were chosen to have an impedance margin with the load, and so will have similar reactance at the power frequency. As we know, when an inductor and capacitor have the same reactance, they become a resonator.

Furthermore, assuming you could control the resonance, there is another problem. Nonlinear saturation of the magnetic core leads to a motorboating condition where the tranformer primary jumps to twice the mains voltage with a square wave! it buzzes like mad!
Synchronous motors would probably have similar problems although it would be fun to try out. I don't know about other motor types like brushed AC motors. On Monday, January 15, 2018, 9:06:58 AM CST, David C. Partridge <@perdrix> wrote:

I gave in and ordered the fan ...

-----Original Message-----
From: [] On Behalf Of Adrian
Sent: 15 January 2018 13:46
Subject: Re: [TekScopes] OT: Sunon SP100A 115V fan (0.26A) in a 240V unit

Hi David,

Stupid question ...I'm assuming this is not a tapped transformer input so you just leave the fan across 1/2 the primary?

Other than that I would go for the replacement fan, from the little I've done fans seem to present a strange (and to some extent dynamic) load and a capacitive voltage divider may not be quite straightforward?

...and fans wear out anyway.....


Join to automatically receive all group messages.