Author Topic: Ballasting a Mercury Vapor bulb  (Read 495 times)
Keyless
Newbie
*
Offline

Posts: 32
View Gallery

Ballasting a Mercury Vapor bulb « on: November 10, 2016, 07:28:45 PM » Author: Keyless
Ok, say I wanted to ballast a 175 watt or 400 watt Mercury vapor bulb via an incandescent or linear halogen lamp; how would I go about selecting what size tungsten bulb to use?


At minim I am thinking a 240 volt supply for an H33 or H39 US bulb (as this is the typical open circuit voltage for 175 watt mercury ANSI ballasts)and a bulb that causes about a 60% voltage drop once the mercury lamp is fully warmed up.
« Last Edit: November 10, 2016, 07:31:59 PM by Keyless » Logged
BlueHalide
Sr. Member
****
Offline

Posts: 293
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #1 on: November 10, 2016, 09:46:49 PM » Author: BlueHalide
Ive successfully ran a Sylvania 400w MV lamp with a 500w and 300w (800w total) linear halogens in series on 240v (standard split phase...no neutral).The lamp burned stable for the couple hours I left it on and the halogens still produced a good amount of light themselves. Whats odd is that I could only produce this with 400w sylvania lamps, I tried a 400w GE on the same setup, and it extinguished within a half hour.

So, it really depends on the manufacturing tolerances between brands, and even batch to batch of the same brand. Youre going to be experimenting a lot as the ratio of filament to mercury wattage varies incredibly ive found due to these slight differences between brands. I also was able to run a chinese westinghouse 100w MV on 250w of incandescent without failure. I used a 150w and 100w standard incandescents for that.
Logged
Keyless
Newbie
*
Offline

Posts: 32
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #2 on: November 10, 2016, 10:04:15 PM » Author: Keyless
Thanks. So it looks like I need a little under about.75 x the amount of incandescent wattage to rated mercury wattage. As for your extinguishing, Im guessing 2 things:

1. The bulb was either over driven or under driven causing excessive voltage drop across the arc tube. Metal Halide and MV can also be made to cycle (like HPS) under the right conditions.


2. The lack of inductance in the circuit might be playing a role. The arc current is none linear due to the needed strike voltage being well above zero after each reversal in a sign wave, thus an inductive source will have a "peaked" or "spiked" output voltage driving an arc tube where as a resistor will not give this effect. Lower pressure fills are less effected by a none inductive ballast (not needing as high a voltage to sustain or strike) than a high pressure fill, hence the brand difference. See this:


https://www.youtube.com/watch?v=ZhSuFJ171u0


Although nothing is certain as I do not know much about HID lamps, the above is just a pure educated guess. It might be bogus. As for your lamp, how was hot restricking?
« Last Edit: November 10, 2016, 10:09:59 PM by Keyless » Logged
Keyless
Newbie
*
Offline

Posts: 32
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #3 on: November 10, 2016, 10:11:39 PM » Author: Keyless
Also, do those halogens need to be rated 230 volts or 120 will do?
Logged
BlueHalide
Sr. Member
****
Offline

Posts: 293
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #4 on: November 10, 2016, 10:51:26 PM » Author: BlueHalide
The halogens were rated 120v, so that very well could have made a difference, they were clearly quite significantly overdriven until the mercury lamp warmed up a bit. As far as I know 240v halogen lamps dont exist under 5Kw here in the US, at least ive never seen one under that wattage.

Also worth noting that the rated power of most of the generic chinese MV lamps (175w and 100w in particular) varies greatly. Most chinese 175w lamps are actually 125w lamps being overdriven (so they can use the same arctube for both euro and US market lamps)
Logged
Keyless
Newbie
*
Offline

Posts: 32
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #5 on: November 10, 2016, 11:07:55 PM » Author: Keyless
Over driven halogens, so I might need to find some 230 volt bulbs. When the bulb is warmed up, is the voltage divide between each 50/50? Speaking of China I am basically I am trying to replicate this, which I think is one of the coolest things Ive seen:


http://sell.lulusoso.com/upload/20120314/Self_Ballast_Metal_halide_lamp.jpg
Logged
BlueHalide
Sr. Member
****
Offline

Posts: 293
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #6 on: November 11, 2016, 09:18:56 PM » Author: BlueHalide
I have a Denkyu brand clear 275w SBMV lamp that looks similar to that one but in an ED28 envelope. Its rated for 120v and therefore has the preheating filament in the arctube, whats interesting is the halogen lamp overpowers the arctube in this particular one and doesnt really dim down after initial switch on, the lamp runs stable but the mercury arctube is pathetically dim and doesnt change the lamp's warm halogen color much. Kill-a watt measures 322w
Logged
Medved
Hero Member
*****
Offline

Gender: Male
Posts: 3510
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #7 on: November 11, 2016, 11:22:21 PM » Author: Medved
I have a Denkyu brand clear 275w SBMV lamp that looks similar to that one but in an ED28 envelope. Its rated for 120v and therefore has the preheating filament in the arctube, whats interesting is the halogen lamp overpowers the arctube in this particular one and doesnt really dim down after initial switch on, the lamp runs stable but the mercury arctube is pathetically dim and doesnt change the lamp's warm halogen color much. Kill-a watt measures 322w


That sounds like there is a vacuum loss in the outer (there is insufficient thermal insulation of the MV burner, preventing it from warming up - therefore remains at very low voltage drop).
Logged

No more selfballasted c***

Medved
Hero Member
*****
Offline

Gender: Male
Posts: 3510
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #8 on: November 11, 2016, 11:41:15 PM » Author: Medved
Also, do those halogens need to be rated 230 volts or 120 will do?

The MV does drop around 110V, but that is nearly a rectangular waveform shape.
Because of the shape difference, straight rms voltage sum does not work there in the circuit, so the resistive ballast (the incandescent,...) gets about 150Vrms once the MV reaches the rated 110V.

The halogen needs to be rated at 240V (so an European 230V halogen is OK), the main reason is, the halogen already on the rated voltage tends to locally overheat when warming up. It is because the colder filament has lower resistance, so allows some hotter sections to get higher than rated current and so are able to briefly reach higher than rated temperature.
Mainly with halogens (where the filament temperature is designed higher even on rated voltage) this temperature is enough to cause crystal change in the tungsten and so the filament loosing strength there.
So that means the halogens have to be rated for the maximum voltage present there during the initial phase of the startup, while the normally classic filament ballasts are sufficient to be rated for the final 150V (where it remains the longest time; as the classic filament runs normally cooler, it has greater margin for the uneven temperature distribution, so it could be left temporarily overdriven during MV warmup)

In any case the incandescent should be designed with sufficient dielectric strength for the full 240V and that is the main show stopper for the 120V rated lamps (it mnay work fine, but there is very high chance some overvoltage spike causes an arc in the incandescent, making it effectively a short circuit, destroying both the incandesceent and the MV; the 230V incandescents have more Nitrogen in the fill just for this reason)
Logged

No more selfballasted c***

Keyless
Newbie
*
Offline

Posts: 32
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #9 on: November 12, 2016, 12:01:01 AM » Author: Keyless
Medved, excellent explanation!  Smiley  Incandescent Lamp


One of my choices behind halogen is that during burn out its impossible for an internal short circuit arc like with an standard incandescent bulb. Not sure where the 230 volt ones rank. And while the incan may have fuse leads, their time current curve may not be enough to prevent arc tube rupture or temporary over driving of the MV lamp. Not sure how US self balalsted MVs did away with this issue.

Logged
Medved
Hero Member
*****
Offline

Gender: Male
Posts: 3510
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #10 on: November 12, 2016, 05:20:28 AM » Author: Medved
Medved, excellent explanation!  Smiley  Incandescent Lamp

One of my choices behind halogen is that during burn out its impossible for an internal short circuit arc like with an standard incandescent bulb. Not sure where the 230 volt ones rank. And while the incan may have fuse leads, their time current curve may not be enough to prevent arc tube rupture or temporary over driving of the MV lamp. Not sure how US self balalsted MVs did away with this issue.


The 120V makes the arc way less likely to even occur and if so, it gets way easier extinguished. So the damage is either none at all, pr way less severe (so the lamp just stops lighting and that is all). Usually a single fuse within the lamp base is more than enough to ensure this.

The 230V makes the arcs way more potent, so way more difficult to extinguish.
In the incandescents it means not only the different gas fill (more Nitrogen in it, even when it is hurting the efficacy*lifetime figure).
As a safety measure for the EOL arcing, two fuses, each in one lead are must and even that is in some circumstances not enough to prevent the fat arc from blowing off the bulb (in installations with low impedance, so high short circuit currents).

The halogens are not more robust intinsically, but often the design features some measures against the EOL arc already within the bulb (e.g. multiple filament compartments preventing a single arc to spread between the inputs, tungsten filament section fused into the glass acting like an additional fuse,...)
But because they are smaller, the halogens tend to create the arc as often as the normal Argon/Nitrogen incandescents do. And there are even quite a few even 120V halogen models, which are notorious for liking to explode at the EOL with severe arcing marks. Something I've never heard of with the standard incandescents on 120V.

For the SBMV the incandescent part uses similar features as the standard incandescents: Nitrogen in the gas fill, fuses in the socket.
However with the halogen ballasted ones, I'm not sure, but there their origin is quite significant factor (most of them are made in China...)
Logged

No more selfballasted c***

Keyless
Newbie
*
Offline

Posts: 32
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #11 on: November 13, 2016, 03:12:40 AM » Author: Keyless
Brilliant explanation once again!  Cheesy Any idea on the incandescent to mercury wattage ratio, or how the voltage divides across each from cold start up to full run? 
Logged
Medved
Hero Member
*****
Offline

Gender: Male
Posts: 3510
View Gallery

Re: Ballasting a Mercury Vapor bulb « Reply #12 on: November 20, 2016, 01:55:11 PM » Author: Medved
For a 110V arc and a 230V mains, you need an incandescent with power rating about 3.6x the rated arc wattage. The total input power will be then  about 2.6x the arctube rating, the power dissipated on the incandescent about 1.6x the arctube rating.
So for an 80W MV you need about 300W incandescent (it will yield roughly 84W into the MV). The total power will be about 216W, the ballast will dissipate roughly 130W.

These numbers are a result of a kind of simulation I've done in Excell (calculating, how the voltages and currents evolve over the time within the mains period,... - so a brute force numerical method, crude, but works...)
Logged

No more selfballasted c***

Print 
© 2005-2017 Lighting-Gallery.net | Powered by SMF 1.1.21 | SMF © 2015, Simple Machines