MV warm-up times

[Travis Evans]

A couple of weeks ago I added a 100-watt H38 mercury floodlight fixture
to my collection.* It came with a clear “Caster†MV lamp, and I also
bought a Phillips deluxe white H38 when I got the fixture so I could get
a feel for what both types of mercury lamps are like.

While playing around with it I made the interesting observation that
while the clear lamp has a fairly long warm-up time of about 4-5
minutes, the Phillips DW lamp in the same fixture seems to have a much
shorter warm-up period of around 2 minutes--about the same as my M90 MH
lamp and fixture. This makes me curious what accounts for the difference.
Do phosphored mercury lamps have generally shorter warm-up times for
some reason, or is it just the difference in brands and lamp
construction? I also wonder if ballasts of the same ANSI code but
different makes could result in different warm-up periods of a particular
compatible lamp.

I actually kind of wish the Phillips lamp had a long warm-up period like
the clear one. There's something about longer warm-up times that are
more interesting and “exciting†to me for some reason.

_______________
* Apparently Home Depot was really trying to get rid of them. They were
located in a totally different isle from the other yard lights, the
price had been marked down heavily (around 23 USD, originally about
45-50 USD), two of them had been returned [maybe the people who had
initially bought them couldn't stand the color of the included clear
mercury ], there weren't many left, and the boxes were rather dusty.

 

[Don Klipstein]

A couple of weeks ago I added a 100-watt H38 mercury floodlight fixture
to my collection.* It came with a clear “Caster†MV lamp, and I also
bought a Phillips deluxe white H38 when I got the fixture so I could get
a feel for what both types of mercury lamps are like.

While playing around with it I made the interesting observation that
while the clear lamp has a fairly long warm-up time of about 4-5
minutes, the Phillips DW lamp in the same fixture seems to have a much
shorter warm-up period of around 2 minutes--about the same as my M90 MH
lamp and fixture. This makes me curious what accounts for the difference.
Do phosphored mercury lamps have generally shorter warm-up times for
some reason, or is it just the difference in brands and lamp
construction? I also wonder if ballasts of the same ANSI code but
different makes could result in different warm-up periods of a particular
compatible lamp.

I suspect the lamps had different arc tubes. I have seen 175 watt H39
clear mercury lamps with arc tubes different enough to have arc length
about 1 centimeter different.

- Don Klipstein ([email protected])

 

[TKM]

A couple of weeks ago I added a 100-watt H38 mercury floodlight fixture
to my collection.* It came with a clear â?oCasterâ? MV lamp, and I also
bought a Phillips deluxe white H38 when I got the fixture so I could get
a feel for what both types of mercury lamps are like.

While playing around with it I made the interesting observation that
while the clear lamp has a fairly long warm-up time of about 4-5
minutes, the Phillips DW lamp in the same fixture seems to have a much
shorter warm-up period of around 2 minutes--about the same as my M90 MH
lamp and fixture. This makes me curious what accounts for the difference.
Do phosphored mercury lamps have generally shorter warm-up times for
some reason, or is it just the difference in brands and lamp
construction? I also wonder if ballasts of the same ANSI code but
different makes could result in different warm-up periods of a particular
compatible lamp.

I actually kind of wish the Phillips lamp had a long warm-up period like
the clear one. There's something about longer warm-up times that are
more interesting and â?oexcitingâ? to me for some reason.

_______________
* Apparently Home Depot was really trying to get rid of them. They were
located in a totally different isle from the other yard lights, the
price had been marked down heavily (around 23 USD, originally about
45-50 USD), two of them had been returned [maybe the people who had
initially bought them couldn't stand the color of the included clear
mercury ], there weren't many left, and the boxes were rather dusty.

Mercury lamps are fast becoming obsolete in the U.S. because the 2005
Federal Energy Policy Act requires that ballasts for mercury lamps can no
longer be manufactured or sold as of January 1, 2008.

There are other ballasts that will operate the lamps, but they are more
costly. And mercury lamps, of course, are relatively inefficient. It's a
good time to find lamps that will shortly become historical curiosities.

Terry McGowan

 

[Andrew Gabriel]

Travis Evans wrote:
[snip]

Do phosphored mercury lamps have generally shorter warm-up times for
some reason, ...?

Yes, they do. The phosphor redirects some of the radiation back to the burner
and as a result the burner reaches optimal temperature faster.

I doubt that the phosphor alone can account for the faster
warm-up time. It does not trap or reflect enough energy to
make any significant difference. I agree with Don that the
arc tubes in the two lamps must be different.

It would appear to, but I have done some measurements on two identical HPM lamps
and the results seem to validate the redirection hypothesis.

The lamps are the HQL 80W and the HQA 80W. The internal construction is
identical, as they are of exactly the same power. The HQL always warms up
faster.

Could it be that the UV components which exite the phosphor achieve
higher output first? That cause apparently faster run-up time in a
fluorescent lamp. You could detect this by seeing how the spectral
components ramp up relative to each other during run-up.

 

[TKM]

Victor Roberts wrote:
On Mon, 29 Sep 2008 15:10:25 +0300, "I.N. Galidakis"

Travis Evans wrote:
[snip]

Do phosphored mercury lamps have generally shorter warm-up times for
some reason, ...?

Yes, they do. The phosphor redirects some of the radiation back to the
burner and as a result the burner reaches optimal temperature faster.


I doubt that the phosphor alone can account for the faster
warm-up time. It does not trap or reflect enough energy to
make any significant difference. I agree with Don that the
arc tubes in the two lamps must be different.

It would appear to, but I have done some measurements on two identical
HPM
lamps and the results seem to validate the redirection hypothesis.

The lamps are the HQL 80W and the HQA 80W. The internal construction is
identical, as they are of exactly the same power. The HQL always warms
up
faster.

Could it be that the UV components which exite the phosphor achieve
higher output first? That cause apparently faster run-up time in a
fluorescent lamp. You could detect this by seeing how the spectral
components ramp up relative to each other during run-up.

I cannot check that, so I cannot tell. However, there's a dead-on
giveaway,
which provides a sort of a super-clue for the redirection hypothesis:

I have measured the temps of both envelopes and the envelope of the HQL
runs
hotter after warmup. This is the result of having more thermal radiation
produced there. Why is there more thermal at the phosphored glass
envelope?
Because we have energy conversion there. UV -> Vis and apparently as a
byproduct
of the previous, UV -> IR.

On a glass envelope there is still some thermal from absorption, but most
of the
UV upwards of 350-365nm seems to escape.

The processes: UV -> Vis is not terribly efficient in this case, hence one
should get some extra heat there. Not very much, but perhaps enough to
make the
envelope a heat radiator which aids the burner in reaching equilibrium
faster.

Did you measure the lamp current vs. time as the lamps warmed up? Higher
current
earlier in the warm-up process would make the lamp warm up faster.

Terry McGowan

 

[Don Klipstein]

On Mon, 29 Sep 2008 15:10:25 +0300, "I.N. Galidakis"

Travis Evans wrote:
[snip]

Do phosphored mercury lamps have generally shorter warm-up times for
some reason, ...?

Yes, they do. The phosphor redirects some of the radiation back to the
burner and as a result the burner reaches optimal temperature faster.


I doubt that the phosphor alone can account for the faster
warm-up time. It does not trap or reflect enough energy to
make any significant difference. I agree with Don that the
arc tubes in the two lamps must be different.

It would appear to, but I have done some measurements on two identical
HPM
lamps and the results seem to validate the redirection hypothesis.

The lamps are the HQL 80W and the HQA 80W. The internal construction is
identical, as they are of exactly the same power. The HQL always warms
up
faster.

Could it be that the UV components which exite the phosphor achieve
higher output first? That cause apparently faster run-up time in a
fluorescent lamp. You could detect this by seeing how the spectral
components ramp up relative to each other during run-up.

I cannot check that, so I cannot tell. However, there's a dead-on
giveaway,
which provides a sort of a super-clue for the redirection hypothesis:

I have measured the temps of both envelopes and the envelope of the HQL
runs
hotter after warmup. This is the result of having more thermal radiation
produced there. Why is there more thermal at the phosphored glass
envelope?
Because we have energy conversion there. UV -> Vis and apparently as a
byproduct
of the previous, UV -> IR.

On a glass envelope there is still some thermal from absorption, but most
of the
UV upwards of 350-365nm seems to escape.

The processes: UV -> Vis is not terribly efficient in this case, hence one
should get some extra heat there. Not very much, but perhaps enough to
make the
envelope a heat radiator which aids the burner in reaching equilibrium
faster.

Did you measure the lamp current vs. time as the lamps warmed up? Higher
current
earlier in the warm-up process would make the lamp warm up faster.

If the lamps are the same, and warmed up on the same ballast, what I
would check for is lamp voltage as a function of time. If lamp B is
actually warming up faster than lamp A, then the voltage across lamp B
will be increasing more rapidly. (The lamp voltage normally decreases
over the first few to several seconds and then increases.)

- Don Klipstein ([email protected])

 

[TKM]

Andrew Gabriel wrote:
On Mon, 29 Sep 2008 15:10:25 +0300, "I.N. Galidakis"

Travis Evans wrote:
[snip]

Do phosphored mercury lamps have generally shorter warm-up times
for
some reason, ...?

Yes, they do. The phosphor redirects some of the radiation back to
the
burner and as a result the burner reaches optimal temperature
faster.


I doubt that the phosphor alone can account for the faster
warm-up time. It does not trap or reflect enough energy to
make any significant difference. I agree with Don that the
arc tubes in the two lamps must be different.

It would appear to, but I have done some measurements on two identical
HPM
lamps and the results seem to validate the redirection hypothesis.

The lamps are the HQL 80W and the HQA 80W. The internal construction
is
identical, as they are of exactly the same power. The HQL always warms
up
faster.

Could it be that the UV components which exite the phosphor achieve
higher output first? That cause apparently faster run-up time in a
fluorescent lamp. You could detect this by seeing how the spectral
components ramp up relative to each other during run-up.

I cannot check that, so I cannot tell. However, there's a dead-on
giveaway,
which provides a sort of a super-clue for the redirection hypothesis:

I have measured the temps of both envelopes and the envelope of the HQL
runs
hotter after warmup. This is the result of having more thermal radiation
produced there. Why is there more thermal at the phosphored glass
envelope?
Because we have energy conversion there. UV -> Vis and apparently as a
byproduct
of the previous, UV -> IR.

On a glass envelope there is still some thermal from absorption, but
most
of the
UV upwards of 350-365nm seems to escape.

The processes: UV -> Vis is not terribly efficient in this case, hence
one
should get some extra heat there. Not very much, but perhaps enough to
make the
envelope a heat radiator which aids the burner in reaching equilibrium
faster.

Did you measure the lamp current vs. time as the lamps warmed up? Higher
current
earlier in the warm-up process would make the lamp warm up faster.

If the lamps are the same, and warmed up on the same ballast, what I
would check for is lamp voltage as a function of time. If lamp B is
actually warming up faster than lamp A, then the voltage across lamp B
will be increasing more rapidly. (The lamp voltage normally decreases
over the first few to several seconds and then increases.)

- Don Klipstein ([email protected])

Measuring either lamp voltage or current vs. time would indicate some
differences between the two lamps, of course. My point is that two lamps
that look the same physically may not be the same electrically even if
operated on the same ballast. Are those differences due to lamp-to-lamp
variations or something else like the way the lamp coating handles the
infrared emissions. I don't know.

HID lamps do vary by as much as 15% from their nominal design voltages from
what I recall and so lamps operate within
"trapezoids" when lamp wattage is plotted against lamp voltage. See an
example (for HPS lamps) at:
https://secure.ge-lightingsystems.c...data/otherPDF/gea12000m_technical_section.pdf
on Page T-7.

Terry McGowan