Catastrophic lamp failures

ship

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Illinois
Wow! That's an interesting failure I have never seen before as described.

Lamp ceramic looks a bit old and discolored perhaps by way age or from rapid gas escape. Either could do similar. Not familiar with any single ended capsule halogen capsules inside a PAR 64 lamp. This is a really odd concept for me... why? Lamp engineers spent many years in the 60's in developing a single ended halogen lamp. Later the 120v halogen PAR 64 lamp concept as upsised from PAR 56. This PAR 64 lamp operates best with a dual ended capsule lamp capsule from the early 70's, in spinning the bottle.

Capsule is not innocent - do I see failed "Getter" in smoke ring above it, even if not itself blackened? What's a Getter doing in a PAR 64 lamp? What's with a single ended PAR 64 lamp capsule in a lot of work to make it single ended, - perhaps a "Base Up to Horizon" type problem created failure problem?

This is an alien failed lamp you should save as best possible for Mark from Osram. Put on hold a year or two for .... time and funding to be free'd up so this lamp example can be sent back to the engineers. Not like this question is a rush - more a curiosity.

I have a note about a Thorn GFF lamp existing. One would think Ansi code lamps would be on-line. FFP is troubling but if the basic standards of FFP, it would qualify. Single ended... why?
GFF Thorn (disc.) PAR 64, Quartz 67x68° ?1 Kw PAR64
 

DELO72

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The lamps are filled with nitrogen (inert gas that helps prevent oxidization (can't oxidize if there's no O2!) of the moly foil in the pinch seals of the inner capsule), So if it was under pressure, heated up, and the seal of the lens to the reflector wasn't perfect, they could easily shatter and separate under pressure. With large PAR lamps more than any other Halogen lamp type, it really IS rocket science to get them to seal properly without stress in the quartz. And I know this because a colleague of mine was an aerospace Engineer prior to working in quality (years ago) at the Sylvania Large PAR factory in Kentucky. In his words, "It does take a rocket scientist- I ought to know. I am one."
 

DELO72

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New Hampshire
Not familiar with any single ended capsule halogen capsules inside a PAR 64 lamp. This is a really odd concept for me... why? Lamp engineers spent many years in the 60's in developing a single ended halogen lamp. Later the 120v halogen PAR 64 lamp concept as upsised from PAR 56. This PAR 64 lamp operates best with a dual ended capsule lamp capsule from the early 70's, in spinning the bottle.
It's basically acting like a Double-ended lamp. They took a CC8 SE lamp and turned it on its side-- Voila! a double-ended CC6 lamp! :) It's cheating... but it's clever.
 

ship

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I have no idea of what the above message is saying - curious to learn.

"I don't suppose you've heard the sound of an NTC operating MOSFET going kablewey?"

Was just helping my child with homework tonight, similar subject of I don't understand this, and the point of the education was, if you don't understand ask help. No shame in that. I'm asking.
 

RonHebbard

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Waterdown, ON, CA
I have no idea of what the above message is saying - curious to learn.

"I don't suppose you've heard the sound of an NTC operating MOSFET going kablewey?"

Was just helping my child with homework tonight, similar subject of I don't understand this, and the point of the education was, if you don't understand ask help. No shame in that. I'm asking.
I suspect kable wey = Ka Boom in Shipese.
Toodleo!
Ron Hebbard
 

TheaterEd

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I have no idea of what the above message is saying - curious to learn.

"I don't suppose you've heard the sound of an NTC operating MOSFET going kablewey?"

Was just helping my child with homework tonight, similar subject of I don't understand this, and the point of the education was, if you don't understand ask help. No shame in that. I'm asking.
Kablooie?

5720ea1e4ee598f322b783dcb2feda67.jpg
 

EdSavoie

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Oct 19, 2016
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Windsor, ON, Canada
NTC = Negative Temperature Coefficient
This means it will heat up as current passes through it, but it will draw more current as it heats up. most MOSFETs (a high efficiency transistor used for switching type power supplies) operate as NTC.

This means that if the cooling system fails / the components feeding the MOSFET alllow too much current to pass, it can very quickly hit a critical point where it draws more power when it gets hot, and it keeps getting hotter so it draws more power.

Once it hits the runaway point, it will very quickly spiral out of control, blowing with anything between a quaint little "pop" or a rather frightening "BANG" depending on the transistor, current and luck.

The closest analogue to this behavior I can think of is how an arc lamp can die violently if you don't have something to limit the current. unlike an incandescent lamp which essentially starts as a dead short and then draws less power as it heats up and it's resistance increases.
 

TimMc

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Feb 15, 2017
NTC = Negative Temperature Coefficient
This means it will heat up as current passes through it, but it will draw more current as it heats up. most MOSFETs (a high efficiency transistor used for switching type power supplies) operate as NTC.

This means that if the cooling system fails / the components feeding the MOSFET alllow too much current to pass, it can very quickly hit a critical point where it draws more power when it gets hot, and it keeps getting hotter so it draws more power.

Once it hits the runaway point, it will very quickly spiral out of control, blowing with anything between a quaint little "pop" or a rather frightening "BANG" depending on the transistor, current and luck.

The closest analogue to this behavior I can think of is how an arc lamp can die violently if you don't have something to limit the current. unlike an incandescent lamp which essentially starts as a dead short and then draws less power as it heats up and it's resistance increases.
Thermal runaway.... why didn't ya just say so? ;)
 

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