ID this device: ELMWOOD 99/30 3100-1 L158

[IronJungle]

I hate to do this because it always ends with a google page slap. That said, I have googled away and still can't find a datasheet. I throw myself on the mercy of the forum and all it's friendly engineering snarkiness.

I unscrewed four of these from a BIG heat sink. The original product was used to calibrate high end DC power supplies (also yielded some nice precision 1/2 ohm and 1 ohm resistors).

Three pics attached. The markings show ELMWOOD 99/30 3100-1 L158. It is a two lead device. I thinking RTD [maybe], but would like a datasheet.
Any help?

 

[premelec]

From your description it might have been an 'active load' and these could just be older power transistors - anyhow you might test them as though they were and see if they are [bipolar...] - otherwise no clue

 

[Buzby]

Hi,

I couldn't find a close match either, but a Honeywell 3100 is a thermostatic switch.

My guess is 99/30 is the date, 3100 the model number, and L158 some kind of temperature spec, 'C, 'F, or a code.

Suggest you put a ohmeter across it and heat it up !.

Good luck,

Buzby

EDIT : The 'switch' idea is possible, because both leads are the same colour, suggesting it didn't matter which way round they were fitted.

EDIT Again : 158'F is 70'C, a good temperature to shut down at if your BIG heatsink is getting hot !.

 

[john2051]

It looks like elmwood electronics specialise in thermal switching etc.
was this connected to a fan?
I think as buzby says theres a good chance it is a thermal switch. I couldnt find the number , but plenty of idenical
packages.
regards john

 

[IronJungle]

The four devices where connected to a pretty complex PCB with lots and lots of SMT 'stuff' on it; I did not take note on the exact connection. There where no fans.

I will put an ohm meter on it and apply some heat. I did do that, but has expecting a change in R with a change in heat. I really did not test with the expectation of heat making the device act as a switch.

I will report back....

 

[IronJungle]

OK, back from the labs and we have a result.

At room temp 0.00 ohms across the leads. Hit the device with a pencil torch and it goes to an open circuit. My guess is that Buzby is correct in his assumption that this crossover happens at 158F.

Beats me what I'll do with these, but into the kit they go.

Thanks all!

 

[hippy]

I hate to do this because it always ends with a google page slap.

As well as Google, there's always the possibility of emailing the manufacturer.

 

[g6ejd]

They look like thyristors to me, hence the large heatsink - open circuit until triggered. I used to use devices that looked like these, I estimate about 100Amp or more devices.

 

[westaust55]

I tend to concur with Buzby.

from some research a few days ago, Elmwood Sensors (maufacturers of thermal sensors amongs other things) became Honeywell Sensors in 2003.

 

[IronJungle]

As is often the case, the forum is helpful. Given a few additional clues from the thread it is confirmed that Buzby is correct (L158 = 158F). Thanks all.