ballast cap vs run cap

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?

Here's what I came up with Mick my friend...

 The main difference is that lighting caps are required to contain a bleed resistor in parallel across the cap s terminals to drain the high voltage contained in the capacitor to safe levels (usually within a minute or so) after the equipment is switched off. Motor run caps don't require bleed resistors due to them being constantly connected to the motor windings which act like a resistor to drain the capacitor after use.

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, [email protected] [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 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.
> SCHEMATIC GIF 8863 BYTES
> The schematic from the above link.
>
> Regards
> Ole
>
>
>
> ---In [email protected], <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?
>

Some have them you have to test them to find out I got several with
internal resistors .
On May 5, 2018 12:26 PM, "[email protected] [EVGRAY]" <
[email protected]> wrote:

>
>
> Here's what I came up with Mick my friend...
>
> The main difference is that lighting caps are required to contain a bleed
> resistor in parallel across the cap s terminals to drain the high voltage
> contained in the capacitor to safe levels (usually within a minute or so)
> after the equipment is switched off. Motor run caps don't require bleed
> resistors due to them being constantly connected to the motor windings
> which act like a resistor to drain the capacitor after use.
> 
>

Some run caps have resistors to, the ballast cap is probably same as a run cap., it's in a tank circuit continuously.Motor start are for pulse non-cont. use only.One can charge a run cap to about 7 times voltage rating is DC strobe pulse mode.
What say you hector?
dg
 

    On Saturday, May 5, 2018 1:29 PM, "James Glinski [email protected] [EVGRAY]" <[email protected]> wrote:
 

     Some have them you have to test them to find out I got several with internal resistors .On May 5, 2018 12:26 PM, "[email protected] [EVGRAY]" <[email protected]> wrote:

     Here's what I came up with Mick my friend...

  The main difference is that lighting caps are required to contain a bleed resistor in parallel across the cap s terminals to drain the high voltage contained in the capacitor to safe levels (usually within a minute or so) after the equipment is switched off. Motor run caps don't require bleed resistors due to them being constantly connected to the motor windings which act like a resistor to drain the capacitor after use.    
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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], <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?

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?

Good point Darrell.  Down here in Australia we use 240 volts for single phase and 415 volts for 3 phase.  We use 240 volt capacitors for single phase motor starts and 415 or 400 volt run capacitors.
George
 

    On Sunday, 6 May 2018, 3:26:32 am AEST, [email protected] [EVGRAY] <[email protected]> wrote:  
 
     
Here's what I came up with Mick my friend...

 

 The main difference is that lighting caps are required to contain a bleed resistor in parallel across the cap s terminals to drain the high voltage contained in the capacitor to safe levels (usually within a minute or so) after the equipment is switched off. Motor run caps don't require bleed resistors due to them being constantly connected to the motor windings which act like a resistor to drain the capacitor after use.