gas discharge tube indentification

[Jay1028]

I have some GDTs that I can't find any info on. Here are the
markings:

3P90L4 - 3 leaded ceramic
CM3-90 - 3 leaded ceramic
CPC9119M - 3 leaded ceramic

I would like to use them for surge protection on the cable where it
enters the house. I plan on mounting them in a small metal box with
f-connectors at each end. The cable is grounded to a ground rod, I
don't know how long and was installed by the cable company with 3ft
of 12ga wire to ground.

If these can't be identified, how can I test them for breakdown
voltage?

Thanks
Jay

 

[Franc Zabkar]

I have some GDTs that I can't find any info on. Here are the
markings:

3P90L4 - 3 leaded ceramic
CM3-90 - 3 leaded ceramic
CPC9119M - 3 leaded ceramic

I'm guessing they are 90V types. The "91" may mean 9 x 10^1.

Anyway I found the following table in this document:
http://www.leutron.de/uploads/media/870010_H35manual.pdf

Table of Tolerances of popular
Gas Discharge Arresters

Uag/N +25%/-20% min Uag max
-----------------------------
230V 184V 288V
90V 72V 113V

Uag/N +/-20% min Uag max
-----------------------------
90V 72V 108V
230V 184V 276V

I would like to use them for surge protection on the cable where it
enters the house. I plan on mounting them in a small metal box with
f-connectors at each end. The cable is grounded to a ground rod, I
don't know how long and was installed by the cable company with 3ft
of 12ga wire to ground.

If these can't be identified, how can I test them for breakdown
voltage?

Thanks
Jay

I don't know the specs for cable applications, but FWIW the above
document has this to say about telephony:

"The most popular gas discharge arrester is used in telephony and has
a nominal static sparkover voltage Uag/N of 230V with tolerance range
of +25%/-20%. The Uag measured should lie in the range from 184V to
288V."

- Franc Zabkar

 

[JeffM]

I have some GDTs that I can't find any info on[...]
If these can't be identified,
how can I test them for breakdown voltage?

The standard way to see the characteristics of a device
is to put it on a curve tracer.
http://www.google.com/images?q=Tektronix-577