I just received a ballast that was supposedly said to be a HX ballast because it did not feature a capacitor in the wiring diagram but it does say the word “cap” on the live lamp wire. It does say that it is an isolating transformer on it. I tested the ballast to see if it works and I found out that it does fire up lamps without a capacitor in series with the lamp. Does this mean that this ballast is a CWA and NOT a HX and that it will get damaged if I use certain HPS retrofit lamps in it like the sylvania unalux and westinghouse econolux lamps?

I’d say it is CWI because the label and wiring diagramme suggest it. There is a wire labeled cap but no mention of it on the label. Does it have some kind of protusion that could house a capacitor ? Also, the label says high power factor, so it must use some kind of cap somewhere in the circuit.

It may rely upon a cap across the supply wires.

I’d say it is CWI because the label and wiring diagramme suggest it. There is a wire labeled cap but no mention of it on the label. Does it have some kind of protusion that could house a capacitor ? Also, the label says high power factor, so it must use some kind of cap somewhere in the circuit.

It did have a capacitor connector that I removed since it had exposed wire.

It did have a capacitor connector that I removed since it had exposed wire.

I also see that this ballast does not specify the microfarad value for the capacitor.

Should I also be worried about underdriving 400w H33 MV lamps and HPS retrofit lamps for 400w MV lamps? Should I also worry about this ballast getting damaged if I use Sylvania Unalux or Westinghouse Econolux retrofit lamps?

The fact it is a HPF and yet it does not specify any capacitor is really very strange, because it is just not possible without one.
So it seems they have omitted the capacitor from the wiring diagram (because hard wired? And what else they omitted?). But then it could be essentially anywhere, so it could be any topology (CWA/I, as well as HX with power factor compensation on the primary).

Maybe if you have any chance to measure the phase of the input current (if it is leading or lagging to the voltage), you may distinguish CWx from HX when measuring it without any load connected:
If the phase is capacitive, it is HX.
If it is inductive, it is CWx.

The fact it is a HPF and yet it does not specify any capacitor is really very strange, because it is just not possible without one.
So it seems they have omitted the capacitor from the wiring diagram (because hard wired? And what else they omitted?). But then it could be essentially anywhere, so it could be any topology (CWA/I, as well as HX with power factor compensation on the primary).

Maybe if you have any chance to measure the phase of the input current (if it is leading or lagging to the voltage), you may distinguish CWx from HX when measuring it without any load connected:
If the phase is capacitive, it is HX.
If it is inductive, it is CWx.

I also notice this ballast does not have the words “constant wattage” or the letters “CW” written on it.

I also notice this ballast does not have the words “constant wattage” or the letters “CW” written on it.

That does not mean it cannot be a CWA/CWI.

The fact it is a HPF and yet it does not specify any capacitor is really very strange, because it is just not possible without one.
So it seems they have omitted the capacitor from the wiring diagram (because hard wired? And what else they omitted?). But then it could be essentially anywhere, so it could be any topology (CWA/I, as well as HX with power factor compensation on the primary).

Maybe if you have any chance to measure the phase of the input current (if it is leading or lagging to the voltage), you may distinguish CWx from HX when measuring it without any load connected:
If the phase is capacitive, it is HX.
If it is inductive, it is CWx.

How can I determine if the phase is capacitive or inductive?

How can I determine if the phase is capacitive or inductive?

With a power meter able to explicitely display reactive power. Some allow that,but many, indeed, dont.

You may determine it ar low voltage (e.g. 12 or 24V from a transformer), thenyou may connect some series resistor to the supply and use an oscilloscope to determine the phase. The lead vs lag behavior will stay the same, even at such low voltage, but it will be safe to mess with the grounded oscilloscope.

Otherwise if youhave an isolation transformer and an oscilloscope, youmay check the phase on the load (it has to be connected tothe lamp). If the load phase leads, it is a CWA, if it lags, it is HX.

How can I determine if the phase is capacitive or inductive?

You can determine the type of load by looking at the oscilloscope waveform. A normal power meter with a power factor indication may work, and you can do the experiments at full voltage and without extra transformer.

The capacitive load lags the current and tend to have a power factor of 0, the inductive load leads the current but I don't know its power factor.





The previous pictures are from this video.

@Binarix128: You've found very nice pictures for that...

@Binarix128: You've found very nice pictures for that...

Thanks! But I'm still not sure what is the power factor of a pure inductive load, and if we add a capacitor the factor becomes 1.

Thanks! But I'm still not sure what is the power factor of a pure inductive load, and if we add a capacitor the factor becomes 1.

PF = 1/Q ...
So with a loss less inductor it would be zero: Because zero losses means zero real power, with some reactive power.

And if we add a perfectly matching loss less capacitor to a loss less inductor, the PF = 0 / 0, so undefined... It will just appear as a pure open circuit. The magic of resonance...