Hi there,

I am curious to try the following and I was wondering if anyone could give me any technical feedback on this.

I have:

1x 80 Watt MV bulb (EURO HPL-N 80 Watt). The lamp operates at 115V, 0.8 A
1x Sylvania QTP 4x32T8/UNV ISN-SC ballast

Is there anyway I can connect the lamp to the ballast (with/without slightly under or overpowering the lamp)?
I know the 80 HPL bulbs are pretty solid so I was just wondering.

Thanks anyone for taking the time to read my question! 

 

First: I guess the ballast you have is an electronic HF type. Here I see the problem with driving a high pressure amp with it: The high pressure arctube design rely on the ar being constricted (by the electromagnetic forces - "Z-pinch") and straight between electrode tips, so stay quite away from the arctube wall. But this "Z-pinch" forces areeffectiveonly at low frequencies. At higher frequencies the arc tend to be thicker, but usually it swirl around. O top of this it tend todevelop an accoustic resonance waveswithin the arctube. All this could lead to a thermal overload of the arctube wall and consequent destruction of the arctube.
Singletrial does not prove anything, as the lamp parameters change slightly over time, so the problem may appear only after some hours.

Now for the curent: The F32T8 are rated at about 0.25A, so three channels parallel would sum up about the correct curent (~0.75A). But all three would have to be parallel (in phase) within the ballast as well.

Four branches would become too high...

Medved - And what if the ballast output is rectified and filtered and fed to the lamp as DC ? Will it work or overload one electrode and cause failure (i mean overload it within the lamp working time, not wearing it over many hours as that can be fixed by switching the lamp polarity at each start swith a latching relay)

Ash: Never operate an AC operated discharge lamp with symmetrical electrodes on DC. This will cause overheating of the electrode that acts as the anode, and lamp failure. Same with fluorescent lamps.
Thats why lamps like Osram HBO and XBO, have a large anode and a small cathode, and must be burned vertically with the anode on the top.

Thanks guys (especially Medved) for your comments.

I am willing to give it a try (I have plenty of 80 Watt HPL-N's) just to see. I just hope the bulb won't explode :0
Sorry, I do not know much about this sort of stuff so I don't mean to sound too stupid 
To confirm, in order to connect the three channels of the ballast in parallel mode, I am going to do the below:



Thanks again!

The arctube may be damaged, but I would guess it will first blow "a bubble" on it's wall...
But always do such experiments with the anticipation of the worst - so here expect the bulb is going to explode, so put it into some fixture, what could handle it (best is rated for an MH lamp)
Better be safe than sorry...

true... thanks. I am starting to have second thoughts about the Ballast's capability to run in parallel mode.
I cannot find a wiring diagram which displays it is possible to run several channels to one lamp.

Well, if you could find a 50W MH ballast and deactivate it§s ignitor, it would be about OK in driving the 80W MV...

Why not 2 fluorescent chokes ?

Why not 2 fluorescent chokes ?

The 120V mains would be too low OCV for a MV...

Yeah I never thought of that. The operating current for an MH 50 Watt bulb is 0.6 A which means the 80 Watt MV lamp would be slightly underpowered.

What is the operating Voltage for a 50 MH lamp?

Oh i missed that we are on 120v there (80w is a lamp size common in 240v countries)

But nevertheless, how about doing just that but with magnetic fluorescent ballasts ? (Rapid Starts, 1 wire from each end)

Hey Ash,

Do you mean just to connect multiple fluorescent ballast in parallel mode type of thing?
Do you recommend any (Rapid start) ballast types I should be using?

I am only guessing here since i have no ballasts of the type i want to try, so i canot test it

Here the 80w merc lamp works right on 2 ordinary 40w chokes in parallel

Since for you the 40w is not a choke but a multiple-wire ballast you'd have to wire 2 ballast outputs in parallel. But they must really be parallel and matched, in their voltage output and in phase with each other

The simplest would be to use ballasts that expect 1 pin of the lamp to be connected to neutral. With ballasts where all lamp wires are separate from live/neutral there is one more concern. to not short any filament heating coil which might be "hard" connected to the line, so requires more measurements and tests to be done to determine the matching between the 2 ballasts

But i think it is possib;le to use any ballast (just with the more complicated testing/matching) and you probably would be able to run 2 mercs on lead/lag with 2 2x40w ballasts ^_^

For the basic 1 lamp i think of something like this :

Maybe some notes:
- These have to be full power ballasts.
- Both have to be ideally of the same make and model
- All used outputs have to be of the same phase - so both lead or both lag. To check this, measure the DC resistance on the output: Lag have few 10's of Ohms, lead have 10's of kOhm or more (there is a capacitor in series, usually equipped with discharge bleeder resistor to make sure the dangerous voltage disappear after switching the power OFF).

When you would have to mix ballasts of different make and/or model, you have to make sure:
- Their OCV is similar
- Their output voltage phase is the same
- Both use the same current phase (lead vs lag).

Note: The test on the 3'rd picture does not recognize one leg as lead and one as lag, it is supposed to check only if the voltage phase is the same and the voltages alone are similar.


And after all that check the real lamp current in the final arrangement, it have to be somewhere between 0.8..1.5A just after startup and settle at ~0.65..0.85A after warmup.

Too low current: lower than from each ballast, mean one ballast is lead and the other one lag. So search for different ballast.
Too high current after warmup: I doubt this would be possible with ballasts in good health, so I would guess one of the ballasts is damaged.
Too high current only just after start: It would wear the lamp faster at startups, but it would mean faster runup. You may keep that.