Body
Hi Mick,
A non-polarized electrolytic capacitor has an oxide layer (dielectric) on both plates while the polarized ones only have the oxide layer on the positive plate (on both sides). https://wiki2.org/en/Electrolytic_capacitor https://wiki2.org/en/Electrolytic_capacitor. The electrolyte actually forms the opposite plate on top of the oxide layer. The non-polarized electrolytes thus have two foils two oxide layers (or four as the foils are oxidized all over) and the electrolyte forming a third 'plate' (or conductor) between the two oxidized foils.
In oil capacitors the oil soaked paper is the dielectric layer.
Regards
Ole
---In [email protected], <mkjekyll@...> wrote :
Great information from everyone, yes the bleed resistor is usually in the pic but until Ole mentioned they are only to start the ark I though they were continuous duty. Never looked at the lighting circuit Ole was so thorough to include.
Warren said he procured a bunch of oil run caps rated at 1000v if memory serves, have not seen any of these around yet.
Ole, what is the difference in the inside build between a non polar electrolytic and an oil run or oil PFC cap?
I think the electrolytic fluid is different than the regular oil insulation fluid but not sure.
On 5/5/2018 1:57 PM, onielsen@... mailto:onielsen@... [EVGRAY] wrote:
Hi Mick,
The ballast of a HID (High Intensity Discharge) lamp would have to be an inductor. https://wiki2.org/en/High-intensity_discharge_lamp. https://wiki2.org/en/High-intensity_discharge_lamp
The capacitor could be for a start discharge to get the arc ignited. This would be just a short pulse and thus wouldn't require a continuous high current through the capacitor.
Here is a page with a schematic for an electronic ballast for HID lamps: https://www.repairfaq.org/sam/jshidbal.htm https://www.repairfaq.org/sam/jshidbal.htm This circuit outputs DC current even though the Wikipedia article tells that DC isn't good for this kind of lamps. The C7 capacitor is the output capacitor that has the total voltage across it. This capacitor won't have big current through it as the current is limited by the series capacitance of the voltage multiplier and the output series resistor R3. A motor run capacitor will have the full run current of the help winding through it and thus must be able to handle that current through extended periods of time. Choose the capacitor for not heating above what the manufacturer recommends. The good capacitors are normally expensive as compared to the bad ones. Check the datasheets to see if fit for the purpose.
The schematic from the above link.
Regards
Ole
---In [email protected] mailto:[email protected], <mkjekyll@...> mailto:mkjekyll@... wrote :
Hector,
If you can respond what is the difference between a HID lighting ballast
cap and a run capacitor?
The lighting caps are much less expensive, both are oil filled and both
can handle a good amount of wattage.
Is the internal build of say a run cap different offering higher Q or
are they somewhat interchangeable?