HQI Magnetic VS. Pulse Start Ballast

[Flowmaster]

What is the difference between these two ballasts? Or will they both fire HQI bulbs?

[PaulErik]

What wattage? Different wattages have different differences.

Both a magnetic HQI 250-watt ballast (ANSI M80) and a magnetic pulse start 250-watt ballast (ANSI M138/M153) will fire/ignite a HQI type lamp. Both ballasts are equipped with an external lamp ignitor (lamp starter). An ignitor is required for HQI type (ANSI M80 and European spec) 250-watt lamps. The main difference is the operating current. A pulse start (ANSI M138/M153) provides less lamp current than a HQI (ANSI M80) ballast. ANSI M80 specification calls for a lamp current of 3 amps and ANSI M138/M153 calls for a lamp current of 2.1 amps. Using a HQI type lamp (built to ANSI M80 or European electrical standard) on a pulse start (ANSI M138/M153) ballast will cause the lamp to be driven under spec (under powered/ reduced wattage). This is not recommended because the lamp never reaches full brightness/operating temperature. The lamp needs to be operated at full power at each start to allow the lamp to properly stabilize. If not short lamp life and color shift may result.

[PaulErik]

A magnetic HQI (ANSI M81) 150-watt and a magnetic pulse start (ANSI M102) will usually fire/ignite a HQI type (Double-Ended) lamp. The lamp current specification for both are the same but the ignition/starting voltage is different. An ANSI M81 lamp has an igniton voltage between 4000-6000 volts and an ANSI M102 lamp has an igniton voltage around 2500-4000 volts (4000 volts maximum). An ANSI M102 ballast generally has a high enough igniton voltage to start most HQI / Double-Ended (DE) lamps. The reason the igniton voltage for a pulse start ANSI M102 is lower is because most 150-watt pulse start lamps are medium base single-ended. These lamp sockets are not able to withstand a starting voltage any higher than 4000 volts.

[PaulErik]

A magnetic HQI 400-watt ballast (None ANSI standard) and a magnetic pulse start ballast (ANSI M135/M155) will fire/ignite a HQI type lamp. The operating lamp current is different. European electrical standard / HQI calls for a lamp current approximately 4 amps and a pulse start ANSI M135/M155 standard calls for a lamp current of 3.25 amps. Using a HQI type lamp (built to European electrical standard) on a pulse start (ANSI M135/M155) ballast will cause the lamp to be driven under spec (under powered/ reduced wattage). This is not recommended because the lamp never reaches full brightness/operating temperature. The lamp needs to be operated at full power at each start to allow the lamp to properly stabilize. If not short lamp life and color shift may result.

[PaulErik]

For reliable, safe and optimal performance it is recommended to match lamps with the proper type ballast (not just wattage). Each specification/standard has different electrical specifications/requirements. In North America we use ANSI (American National Standards Institute) codes to match lamps and ballasts.

[jthao]

paulerik..... wow you know your stuff!!!! Great info!!

[Flowmaster]

Yes, thanks. I thought you could fire up de bulbs with a pulse start ballast. I am glad to see what the difference is.

[Insainoreefer]

Ok, heres one for ya PaulErik.......

Can you use a 175w ballast to fire a 150w HQI bulb? Maybe a stupid question I know but I really don't know.

[Insainoreefer]

Maybe I must be more clear,.....

Can you use a 175w magnetic ballast to fire a 150w HQI bulb?

Does the 150w throw more par than a 175w or could it just be the reflectors that I'm using.

I realize that I'm asking a pretty broad question, but I'm just asking in general. I know that there are a lot of factors like ballast, reflectors, and bulbs. but generally if you had to use all the same equipment with the exception of HQI vs mogol. which would be brighter?

[PaulErik]

A magnetic 175-watt pulse start (ANSI M137/M152) will operate a 150-watt metal halide lamp but not properly. The 175-watt (ANSI M137/M152) ballast is designed to provide 1.5amps to the lamp and a 150-watt (ANSI M102/M81) ballast is designed to provide 1.8amps to the lamp. Using a 150-watt lamp on a magnetic 175-watt ballast will actually result in reduced operating wattage (under drive the lamp) and this will result in a color shift and reduced lamp performance.

Most electronic 175-watt ballasts work differently. With a magnetic ballast the ballast limits current (amperage) to the lamp and when the lamp reaches an equilibrium the lamp will set the operating voltage. Electronic ballasts usually output a specified amount of wattage within a certain percentage to the lamp. Using a 150-watt lamp will result in an increased operating wattage (overdrive the lamp). Most manufacturers do not recommend doing this. Some electronic 175-watt ballasts are unable to operate 150-watt lamps because it causes the setup to operate out of spec and may cause lamp flicker or cycling (on/off).

Generally a 175-watt lamp will have more light output / PAR than a 150-watt lamp. The reflectors play a major role. 150-watt DE (Double-Ended) lamps allow for a more compact reflector and sometimes a more effective reflector design.

[Insainoreefer]

Great! Thanks for the info!

[Insainoreefer]

Are there any good reflectors for 175w that don't cost an arm and leg? I've looked at Lumenarc and they want a little more than I'd like to spend.

[PaulErik]

Unfortunately good well designed reflectors are usually not cheap. Well designed reflectors that are utilized correctly/optimally can result in good energy savings in the long run by allowing the use of lower wattage lamps.

[Flowmaster]

Does anyone have a link to the DIY Lumenarc style reflectors?

[Chibils]

PaulErik - not to 'jack the thread, but you know your stuff. I was thinking about dropping the cash for used Lumenarcs, but it seems like such a waste of money. I could buy four new bulbs for the cost of two reflectors. Are they REALLY worth it? How much of a difference do they really make?