I watched a pretty old Big Clive video on the internals of an ignitor. It appeared to generally be of the "semiparallel" category, but very different from American semiparallel ignitors. It had many electronic components (DIAC+TRIAC+other things instead of just a SIDAC). It looks expensive to make. Why do they have to be so complicated? Why not just choose the three-component American style cheap-but-effective semiparallel ignitor?

Superimposed ignitors seem to be more popular there than semiparallel, but I do wonder why this design was chosen.

May be a tradition. Triac may be more robust. Surprisingly, a pile of off-the-shelf parts still can be significantly cheaper than one specialized one. I can speculate that ignition SIDACs probably were firstly developed by an American manufacturer, so these were initially better available in US.

From ignitors i have :

ELT semiparallel ignitor - based on some generic thyristor, fairly simple

Steinitz ST1C - based on BT138 thyristor + few resistors and capacitors

Eltam ES50 - based on Littelfuse K220 SIDAC, with the exact circuit from the datasheet. Probably identical to American ones. https://www.lcsc.com/datasheet/C151184.pdf

And then we have Eltam's ESPI1000, with a PIC microcontroller inside. (The power stage is about same as in the ELT)

So it varies. The complicated ones implement cut off timers and logic for few purposes :

 - Failed ignition attempts still do make some discharge in the lamp. Without them the lamp cools faster, so this might speed up hot restrike time

 - Generating high voltage continuously (and especially without a functional lamp that would clamp the pulse) stresses the insulation on the ballast for no purpose. (Tho most decently made ballasts survive it for years anyway)

 - People dont like cycling lamps, so some prefer a lamp to stay out completely if it failed. (On the other hand, any unmaintained lot with multiple cycling lamps, will still be more lit at any given time with the simple ignitors)

Generally there are two types of semiparallel ignitors, they differ in the ballast winding configuration they require:
One uses the R-C-SIDAC configuration (or equivalent function using more complex circuit allowing additional features like timed EOL shut down or so). These need tap on the ballast winding of about 5% from the lamp end. So far have seen this only in literature, not real commercial type, but I did not researched them that much. My assumption was, adding the separated pulse transformer and making a superimposed ignitor out of this is the more common way.

Then there are circuits based on the semiresonant concept , which are used mainly because of their ability to drive larger capacitance, so longer cable towards the lamp. These use ballast with tap at the 20% from the line input. An example is Philips SN57, but there are multiple implementations, usually varying in the "controller" part.

Wow, this is really complicated. No wonder superimposeds are so common over there, there are multiple non-interchangeable types of semiparallel among even more obscure types! Way easier to just chuck in a superimposed and call it a day.

@Ash
Yes, that ES50 schematic seems to be identical to American ones.

@Medved
Interesting that European SIDAC ignitors use a tap at 5%, IDK the exact percent that American ballasts use but I think it is less than 5%, less than 5V for 240 VOC. Strange that those aren't very popular over there.

That semiresonant-based ignitor I believe is the type I saw in the video. Who knew there were so many different ways to do the same thing?

ES50 uses a tap at 20% from the lamp end. The same ballast with P and L reversed can be used with most other semiparallel ignitors

(European ballast terminal name convention : P and L - ends of the winding, L being the one closer to the tap. D - tap itself)

Also. what does hot restart with American ignitors look like ?

ES50 outputs single flashes about 2..4 times/sec. They are fairly high energy - they are bright, and lamps with loose ignition aids in them (like the Osram wire parallel to the arctube) make audible "ping" sounds

The ELT, ESPI1000, etc put out what seems like a smaller pulse in every half cycle, so 50Hz

Wow, this is really complicated. No wonder superimposeds are so common over there, there are multiple non-interchangeable types of semiparallel among even more obscure types! Way easier to just chuck in a superimposed and call it a day.

@Medved
Interesting that European SIDAC ignitors use a tap at 5%, IDK the exact percent that American ballasts use but I think it is less than 5%, less than 5V for 240 VOC. Strange that those aren't very popular over there.

That semiresonant-based ignitor I believe is the type I saw in the video. Who knew there were so many different ways to do the same thing?

The tap position is dictated by the required pulse voltage. R-C-SIDAC pulsers charge the capacitor at 200V when the sidac triggers, this 200V is then discharged into the short section acting as the primary, the whole winding as a secondary, so multiplying the 200V by 20 you get the usual 4kV pulse required for MH ignition.

So when you use the SIDAC pulser with the 20% tap, you get just 1kV pulses (maybe 1.5kV with some ringing on leakage inductances; but that is not that reliable), that may be barely enough for some HPS but not for MH.

The SN57 style works in a digfferent way: It swings the voltage back and forth via the triac, cycle by cycle building voltages way higher than the mains, stabilizing at about 800V (practical maximum for standard triacs), so factor of 5 step up is sufficient to get the required 4kV ignition pulses.

The ES50 is designed to work with those ballasts, and the ballasts have on them the wiring diagram for ES50

It is rated to 4.5kV output

It is rated for HPS only, but in practice statrs all MH from cold just fine. It does have hard time hot-restriking MH though

It is rated for remote installation, with up to 11m cable between it and the lamp

Inside are the SIDAC with ~220V Vbo, capacitor 2.2uF

Isn't there also some transformer? Because 210V*5=1050V, maybe if I would be VERY optimistic about resonant overshoot (assume zero losses related to the leakage inductance and internal capacitances) it could hypothetically become 2kV, but more realistic maximum will be no more than 1.5kV. Definitely not anything close to 4.5kV.
Maybe some structure similaf to Marx generator (just build using sidacs instead of spark gaps; charging the capacitors in parallel to the 200V of the sidac trigger level, then the sidacs trigger and connect them in series, so in total reach the 800V pulse), like a 4 stage bank, could lead to something close to 4kV. But then there would have to be 4 capacitors and 4 sidacs...

No, but if i will be too bored i may try to scope this....