Ballasts

From Lumenlab

1 Facts
2 FAQs
3 Links
4 Source

Facts

! DANGER- When working with household current please take all necessary precautions. If you are unsure of what you are doing, get some help from someone who does. Capacitors can be lethal; they can store dangerous voltage even after the power is off and must be discharged prior to working with them. They should be discharged with a large resistor. You can use a toaster to function as your resistor if you must. (This is a disclaimer and is being extra cautious, however it has been brought to my attention that coil ballasts have a resistor on board that serves to discharge the capacitor on shutdown. If in doubt it is always best to be on the safe side when dealing with capacitors.)

In order to produce light, metal halide lamps ionize gas within an arc tube. Once an arc has been struck, resistance to the current flow in these lamps is virtually nonexistent. As a result, without a ballast to control the current, the lamp would be destroyed.

Ballasts and lamps are given an ANSI (American National Standards Institute) rating. The ANSI rating # will give you the lamp type and wattage and no lamp or ballast of a different type or wattage will have the same rating #.

There are currently four ratings of ballasts that are of interests to us:

1. M59 -This ballast is used for the old tech probe start 400W metal halide bulb. In particular, it will run the MH400U and the EYE bulb that has been successfully used in many Lumenlab projectors to date. It will run ANY bulb with the M59 rating.

Probe start ballasts have a low current limiting factor because the ballast must be able to supply both a starting and a running voltage. Because of this, lamp efficiency/life is not as good as a pulse start system.

This is the cheapest option and still is used by builders on a very tight budget but is the least desirable because of improvements made with the pulse start system and the electronic ballast.

2. M135/155 -This ballast is made to run the new technology pulse start lamps (eg. Venture-400W/H75/ED28/PS and Ushio-MH400/U/MOG/40/PS). It will run ANY bulb with an M135 rating. Whether or not your M135 ballast also has the 155 designation is of no consequence unless at some point a M155 lamp is specified for the projector. Currently I don't believe that there are any lamps made that solely carry the M155 rating.

Pulse start technology improves the overall performance of metal halide. Lumen output per watt consumed increases by 25% to 50%, depending on lamp wattage and burning cycle, and lumen maintenance is improved as much as 15-25%. In addition, lamp life is extended, color rendition is improved, and warm-up time and restrike time (time from lamp extinguishing until it is cool enough to be started) is cut in half.

Pulse-start metal halide ballasts specifically meet the needs of pulse-start lamps and are not simply probe-start ballasts with added ignitors. Replacing the internal lamp starting probe with an ignitor allows a separation of ballast starting and operating functions. The ignitor starts the lamp and the ballasts' core and coil operates the lamp, allowing for optimization of both lamp and ballast performance.

The traditional CWA metal halide ballast, with its 600v peak open circuit voltage needed to start probe-start metal halide lamps, creates a relatively high lamp current crest factor that compromises lamp performance. Focusing the ballast design solely on lamp operation lowers the lamp current crest factor - resulting in improved lamp life, lumen maintenance and color stability. Isolating lamp starting and operating functions also result in more efficient and cooler ballast operation, as the core and coil no longer needs to supply the 600v starting voltage. This lower open circuit voltage creates lower ballast operating temperatures, resulting in longer ballast life.

Optimized pulse-start ballast/lamp systems boost maintained lumen output by 25% to 50%. Improving the quality and quantity of white light throughout lamp life provides energy savings, since lower wattage pulse-start lamps produce the same light output as higher wattage probe-start lamps. By achieving lumen maintenance of up to 80%, pulse-start lamps reduce light loss over the life by up to one-third compared to probe-start metal halide. Other improvements of pulse-start ballast/lamp systems over traditional probe-start systems are in color rendition, lamp-to-lamp color consistency, and reduced color shift.

This option is between the probe start ballast and the electronic ballast in cost.

3. The Electronic Ballast- This is the Cadillac of ballasts. It has many features that makes it the ultimate ballast for use in projectors.

An electronic ballast uses solid state components to transform voltage. It also changes the frequency of the power from 60 Hz to 20,000 Hz, or higher, depending on the ballast. Because the electronic ballast doesn't use coils and electromagnetic fields, it can function more efficiently and cooler than magnetic. The frequency change also greatly reduces any flicker in the lamp due to burn in or improper power and makes the ballast quiet. Coil ballasts suffer from a 60 cycle hum that can be annoying if the sound is amplified by the enclosure (the hum is similar to the hum of flourescent lights). Also, electronic ballasts are capable of even higher lumen output and longer lamp life than a pulse start coil ballast, and they weigh much less than either coil ballast (coil is ~15lbs). They are as simple as it gets to wire and you don't have to deal with the potentially lethal voltage of a capacitor. It can run pretty much any lamp of the same wattage currently used in Lumenlab projectors.

Some eballasts are unnecessarily bulky and can be quite expensive (eg. the Blueline). Lumenlab has gone to great lengths to supply us with a very compact and light (2.5lbs and measures 2.25" x 3.5" x 7") ballasts that can be purchased in the Lumenlab store. The price for this ballast cannot be beat. They go very quickly so get them fast when they are in stock.

4. S51 - This ballast was originally made for a 400W HPS (high pressure sodium) lamp. It is of interest to us because of manufacturers making metal halide conversion bulbs that will run on these. For some reason these bulbs (the Ushio UHI-S400DD in particular) have better color temp and CRI. This can be squeezed in the the 15" projector and it is ideally suited for use with a 17" and larger panel. Also the fact that it is a tubular shaped bulb makes it suited to new experimental reflector designs. For use with a coil ballast, an ignitor must be used. It can also be run with an electronic ballast.

FAQs

Q: Why does my capacitor look different than some I have seen?

A: There are dry film caps and oil filled caps, either type will work as long as they have the proper rating. Dry film caps look like a plastic cylinder while oil filled ones look like an aluminum can, some are oval.

Q: How can I tell which way to hook up my capacitor?

A: Most caps are not polarized and can be wired either way. If there are no markings on the terminals or color coding on the wires, then it won't matter.

Q: How do I wire my ballast?

A: Most ballasts have a wiring diagram printed on them. If you don't understand it, get some help from someone who does.

Q: Can I use a probe start bulb on a pulse start coil ballast?

A: Yes, but you will likely void the manufacturers warranty on the ballast and the bulb. It may be difficult to start and you will lose the benefits of a pulse start system.

Q: Can I use a pulse start lamp with a probe start coil ballast?

A: No, you may get it to start but it will not light the lamp reliably.

Q: Why won't my lamp start?

A: Your lamp may not start because: there is no power to the ballast; it's the end of the normal lamp life; wiring may be defective or wrong; voltage may be too low; ballast is incompatible, defective or at end-of-life; lamp operating position may be wrong; not enough time for hot restrike has been allowed; high voltage restrike has occurred; or defective or mismatched ignitor is being used.

Q: Why does my lamp flicker?

A: New lamps may "cycle" during initial startup. If the lamp does not stabilize after three starts, reasons may be: wrong ballast; incorrect lamp operating voltage/open circuit ballast voltage; or overloaded circuits.

Q: Why doesn't my lamp make contact with the socket?

A: The lamp is not the correct one for the socket type. The mogul (standard) ANSI - E39 accepts all mogul-based metal halide lamps except position-oriented HOR lamps. The mogul (positioned) ANSI - EP39 accepts universal and horizontally positioned lamps. The E39 is white and the EP39 is yellow.

Q: Can I just add an ignitor to a standard CWA ballast to make it a pulse start?

A: No.

Q: Can I mix different manufacturers ignitors with different manufacturers ballasts.

A: No, all manufacturers recommend using their ignitors with their ballasts.

Q: Can I mix capacitors?

A: Yes, as long as it has the same specs. (capacitor type, µf and voltage ratings)

Q: What is a quad tap ballast?

A: A quad tap ballast has four different input voltages, just connect the proper voltage for your household current and leave the others unused but capped off.

Q: Which of the above mentioned types of ballasts will the Lumenlab electronic ballast replace?

A: Both of the metal halide ballasts. There may be a special eballast made available to replace the HPS coil ballast. I would recommend checking with the Lumenlab store at the time of purchase to be sure that it is compatible with your lamp.