Re: Pulse Start MH Ballast

On 9 Mar 2006 07:56:47 -0800, "Zink"
<(E-Mail Removed)> wrote:

>Can regular (probe start) 400w lamps be used on a 400w Pulse Start
>ballast?
>
>IF SO... does the Pulse Start ballast (M135 SuperCWA) have any
>advantages over a regular ballast (M59 CWA), such as lamp life,
>efficiency and lumen maintenance? Or, does the ballast it make any
>difference with a regular (probe start) lamp?
>
>Ron Seadler

Philips has a warning in their print catalogs that standard
or protected metal halide lamps should not be used in pulse
start fixtures or with pulse start ballasts. They state
doing so will increase the risk of outer bulb rupture.

It is not clear to me why there is an added risk, since both
probe-start and pulse-start 400-watt metal halide lamps are
rated for an operating current of 3.2 amps. There may be a
difference in the starting current, but that will take more
time to investigate.

--
Vic Roberts
http://www.RobertsResearchInc.com
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Before I "specialized" in fluorescent lamps, 41/2 years ago, I was a
Commercial Engineer for OSRAM SYLVANIA and had responsibility for
specifier contacts with field technical information for all lamp types.

Two things about the porbe start lamp design. #1 Their main mechanism
of failure is to fail to start. Hit them with the starting circuit of a
pulse start ballast and they may never fail to start which means they
will continue to operate (at high internal pressures and temperatures
inside the capsule)as they grow gradually weaker and weaker in physical
strength, operating beyond expected life. This can lead to an increased
probability of violent failure of the capsule as the lamp is operating
under conditions it never would have reached if properly ballasted. #2
Lead wire positioning and insulation inside the base of the lamp for a
probe start lamp is based on the open circuit voltage of the M57 (for a
400W) ballast. Granted, there are safety factors built in, but a pulse
start ballast's ignitor circuit provides signifiacntly higher voltage to
get the (differently designed)pulse start lamp to start. There used to
be a hihgher probablility of arcing inside the base if a probe start
lamp were operated on a pulse start circuit. (Note: this may have
changed in the past 5 years, I don't know)

The advantages of higher lumen maintenance for the pulse start lamp was
because the lamp was designed with higher internal capsule fill pressure
when the lamp is not energized. This reduces the "sputtering" losses
from the electrode during startup, but it dramatically increases the
starting voltage required to initiate an arc. Pulse start lamps willnot
strat reliably, if at all, on probe start ballasts. The only effect of
the Super CWA (M135) ballast is to provide the higher starting pulse
required to get the thing started. Once it does strike, as has been
noted, the Short Circuit Currrents and operating current ranges ar the same.

Jeff Waymouth


Victor Roberts wrote:
> On 9 Mar 2006 07:56:47 -0800, "Zink"
> <(E-Mail Removed)> wrote:
>
>
>>Can regular (probe start) 400w lamps be used on a 400w Pulse Start
>>ballast?
>>
>>IF SO... does the Pulse Start ballast (M135 SuperCWA) have any
>>advantages over a regular ballast (M59 CWA), such as lamp life,
>>efficiency and lumen maintenance? Or, does the ballast it make any
>>difference with a regular (probe start) lamp?
>>
>>Ron Seadler
>
>
> Philips has a warning in their print catalogs that standard
> or protected metal halide lamps should not be used in pulse
> start fixtures or with pulse start ballasts. They state
> doing so will increase the risk of outer bulb rupture.
>
> It is not clear to me why there is an added risk, since both
> probe-start and pulse-start 400-watt metal halide lamps are
> rated for an operating current of 3.2 amps. There may be a
> difference in the starting current, but that will take more
> time to investigate.
>

On 9 Mar 2006 20:58:03 -0800, "Zink"
<(E-Mail Removed)> wrote:

>Victor Roberts wrote:
>
>> It is not clear to me why there is an added risk, since both
>> probe-start and pulse-start 400-watt metal halide lamps are
>> rated for an operating current of 3.2 amps. There may be a
>> difference in the starting current, but that will take more
>> time to investigate.
>
>To me, the advantages of Pulse Start seems to be derived from the
>ballast design, and not the bulb.

>To me, the advantages of Pulse Start seems to be derived from the
>ballast design, and not the bulb.

Why do you think the ballast design creates the advantage?
Pulse start lamps have at least two advantages, both in the
lamp. The absence of the starting probe allows the ends to
be made smaller, which makes the arc tubes more isothermal.
This allows for higher cold spot temperatures which produces
higher efficacy, while not overheating the center of the arc
tube. Also, the start is cleaner which leads to less
electrode sputtering and therefore better lumen maintenance.
And, as Jeff has pointed out, the fill pressure is higher,
which also leads to better lumen maintenance.

>It may be that the existence of the
>starter probe induces some sort of functional instability, probably
>during ignition/re-ignition. I seem to remember an article mentioning
>that during the Starting Pulse, the probe was responsible for some
>misdirected arcs, or something similar. It was as if the probes
>presence interfered with the smooth continuity of ignition - with
>apparently detrimental effects.

Mostly the probe requires a large end seal which is then
colder than is desired.

>I would think the lamp would work for a while, but does it remain
>efficient, and then maybe die early from "probe induced" problems? It
>wanted to consider if it was worth it, for myself and others who may
>have really inexpensive and available MH lamps locally available. I
>haven't found Pulse Start lamps around here yet.

I see that you cut that part of my original message that
stated that Philips says probe-start MH lamps operated on
pulse-start ballast have a greater risk of exploding. That
is far worse than short lamp life. It is safety issue that
should be taken seriously.

--
Vic Roberts
http://www.RobertsResearchInc.com
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On 10 Mar 2006 10:14:34 -0800, "Zink"
<(E-Mail Removed)> wrote:

>
>When I initially read about the advantages of Pulse Start technology,
>it was from brochures put out by ballasts manufactureres, mainly
>Advance. I was indunated with explanations about the ballast features,
>but not the important changes which occured on the lamp side of the
>innovation.
>
>After my original post, I kept Googling various terms until I got good
>information on the pulse lamps. The Lighting Research Center had a
>NLPIP article which revealed the details I missed. It looks like the
>ceramic MH lamps are also exclusively Pulse Start.

CMH lamps, like HPS lamps do not have room for a starting
probe in the ceramic end cap - so they are all pulse start -
just like HPS lamps.

--
Vic Roberts
http://www.RobertsResearchInc.com
To reply via e-mail:
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