Ferro-resonant regulators are simple, work reasonably well, but have a few issues:
1. They are noisy! (audible buzz).
2. Older ones often contain a PCB-filled capacitor. You can often tell by the tell-tale smell.
3. Only work at one frequency, so not good regulating the output of a cheap generator.
4. Some versions put out quite a distorted waveform. Pick the ones that have sine-wave output.
5. They don't respond to transients instantaneously and can have odd interactions with their load.
An example of the latter issue was when I ran a high-power solid-state power amp from a 1.5 KVA Sola regulator. Upon powering up, the regulator output went into a weird slow oscillation, about 2 Hz. When I swamped the load with some resistive loading (light bulbs) it stabilized. Class B audio amps and series-regulated power supplies can present a time-lagged negative resistance to the source, which is what I think caused this behavior.
- John Atwood
1. They are noisy! (audible buzz).Yes they can be noisy/er especially as the size increases to past 1kva,
if it's a hi-fi or studio headbanger
run the suckers in another room, attic etc and use extension cords
or get a decent electrician to do an internal wall wiring mod to labelled power point/s.
The power quality will still be ace, you may lose a volt or two on long runs under full load
2. Older ones often contain a PCB-filled capacitor. You can often tell by the tell-tale smell. Swap them out in the exact same microfarad rating for the better brand 660volt ones in metal cans, not plastic cylinder
toys they last a really long time, have not seen a clapped one yet
3. Only work at one frequency, so not good regulating the output of a cheap generator.Yeah, no good on that, although I'd like to try it under full load on a decent stable generator and watch the proceedings on two scopes,
one for the gen output and the other for the ferro-resonant transformer,
and vary the loads on both units to see what the real story is
Maybe some generator sales guru will let me have a go at it one day, if he/she wants an easy sale,
or a speedy refund if the brochure specs don't deliver on the claims
I haven't played with the petrol inverter generators yet, perhaps they are more suitable,
or plainly refuse to start or run such an inductive load ?
4. Some versions put out quite a distorted waveform. Pick the ones that have sine-wave output.The Sola brand is one of the better sine wavers I've seen on a scope, with no load, rated load
...and too much load
5. They don't respond to transients instantaneously and can have odd interactions with their load. I haven't had that happen as severe as that, although I found through trial and error if you warm up the Sola and power amp/s separately, then hook them up,
everyone behaves a lot better.
Using lights to help with the start up is a better way to go, with the option to switch some or all out via a portable switch board.
Anyway, I find one of these monsters with a suitable rated variac can take most line voltage issues out of the equation
and earplugs are cheap