Some MH lamps (Philips HPI-T, Osram HQI-T/DV/DH, Tungsram HgMIF), operates on MV gear. And some MH lamps (Compact and CMH lamps, Osram HQI-T/D HQI-BT/D, Venture Whitelux, GE Arcstream), operates on HPS gear.
In the US, MH lamps operates on dedicated gear for either probe or pulse-start MH lamps, and much effort is needed to design them for operation on the American HPS gear.

The Philips HPI-T lamps say they can run on either SON or mercury gear.

The ignitor would havr to be just a GTO with something that kicks it off very quickly when current starts to flow. How is that comparable to electronic ballast ?

On the other hand, wouldn't this system add in the gear losses atleast as much as is saved by the improvement to the lamp ?

The problem with the arc reignition ignitor is, it would have to generate the voltage spikes for reignition, do that all the time and do not generate RF radio disturbance. All these requirements at once. Meeting one is easy, two stil manageable, but all three would be too much.

Regarding the losses:
Assume the ballast losses are about 10% of the rated lamp power, ballpark numbers.
It would be not that far off to say the ballast losses are proportional to the current.
So if we are talking about 30% difference in current, it means loss difference just about 3%of the lamp rating, so about the spread in ballast losses among makers. The pulse MH had efficacy in the 70lm/W range, the same wattage MV around 50lm/W, so difference of about 30%, so 10x larger than the difference in ballast losses...

And if the compare was meant between using higher arc voltage but an autotransformer ballast vs lower arc voltage with a series reactor?
The autotransformer is not only more lossy, but way more expensive and mainly larger and heavier. I dont think that would have any chance on an European market used to ballast everything by just a series choke...
And we are talking about double ballast losses, double mass and ballast cost, while cathode fall is just about 15V, so the 30% extra arc voltage would mean just 5% higher efficacy, against 10% (from the lamp rating) extra losses in the ballast. Net loss about 5% in system efficacy.
Dont forget in the 120V area they just have no other choice than using some form of voltage step up transformer function in the ballast.

The ignitor provides only the minimum spike to help reignition, made by momentarily shorting across the lamp. not the full power spike for lamp starting, made by discharging a capacitor into a pulse coil (so basically, the reignition helper can be a separate device)

I dont see what is the reliability problem if you suggest there is one. (assume everything built with good components with good safety margins)

I dont see how would reignition without help and reigniton with little help be drastically different in RF emissions ? There is no big difference in the current waveform through the lamp, the reignition helper only makes a small current draw pulse through the ballast, but that is not much different than magnetics on a dimmer, and nobody complains about that ?



Question was to compare :

Pulse Start lamp with today's standard arc voltage

Pulse Start lamp with the higher (Merc) arc voltage + reigniton helper. The increased losses are due to extra time in the period where current flows through the ballast (when the helper shorts it), the efficacy gain is in the lamp

Also, 70 Lm/W is very low by today's standards, even for a Quartz lamp...

I can notimagine, how would you want to make a device capable to generate both high voltage forcold starts, as well as lower voltage for zero cross reignitions and at the sametime prevent each section from interfering with the other one.

Regarding the RF emissions: If the lamp reignites itself, there is no fast pulse generation involved. The ignitors normally employ fast discharges of capacitors into a transformer to keep the circuit simple. But the conseque ce is, it stresses the components so, their life is rather limited (normally they are active just a second or so each start and then are inactive, so even when their life is principally limited, it is way sufficient to outlive the fixture; withfiring 100x per second all the time the light is ON the life would become just some 1khours or so), plus those pulses are strong RF source; not a problemwhe just a second during start, but totally not acceptable for all operation.

It is possible to overcomethese issues today, but it needs modern components not available decades ago when the specs were born.
And the circuit would be not much simpler than the fully electronic square wave ballast of today...

And regarding the 70lm/W: Of course, that is low from todays perspective, but it was very impressive for a white light source 4 decades ago, whenthese specs were created. Since then they became the standard, with many installed fixture in the field, so even when newer lamp designs would allow higher arc voltages, the benefit was not worth the hassle of setting up new standard. It made more sense to put all the effort into improving the lamp designs in general while still following that electrical standard, that brought way better improvements (efficacies 100lm/W with CRI above 80 and stable color over life,...).
The thing is, more standards for very similar product types would mean way more probable mismatch error problems inthe field, which would be seen as light quality and reliability problem by the ultimate end user...

As 2 separate devices :


The zero crossing restrike ignitor is only making a small pulse by momentarily shorting the ballast output

The lamp starting ignitor is the powerful ignitor with capacitor and pulse coil



Logic would be something like :


With its data input being current sense (for example voltage sense across a section of the ballast)

The problem is, the HV ignitor needs a bypass capacitor parallel to its input, to provide the current return path for the ignition impulse. The low voltage reignitor would the  have to fight against this capacitor, that means high current spikes and a lot of disturbance and component wear whenthe GTO turns ON. This is just a first glance thing I've seen there within one minute, there will be way more "little details"...
So you would need some extra current smoothing components there to fight this, so the circuit becomes pretty complex on the power side.
Now if you compare that to the power circuit of a halfbridge electronic HID ballast, it is not that far away complexity wise.
But the fully electronic ballast offers way more advantages than just a reignition helper, so no wonder the HID technology went that way instead...