Is this a varistor ? - UK Vintage Radio Repair and Restoration Discussion Forum

rovernut · 23rd Feb 2016, 10:10 pm

Hi

Is this component a varistor ?, it has a Seimens logo and 600 marked on the end, physically it is about 6mmin diameter and about 5mm long.

It is off a PSU for a Seimens T1000 teleprinter, that I and trying to get going

Any information would be useful and how can I test it ?

Cheers
Richard

Cobaltblue · 23rd Feb 2016, 10:14 pm

looks like a lightening protector (spark Gap)

It should read open circuit until you exceed its protection voltage.

Cheers

Mike T

Nuvistor · 23rd Feb 2016, 10:56 pm

Looks like a spark gap to me as well.

Frank

Andrew B · 23rd Feb 2016, 11:19 pm

+3, I agree, it's a spark gap.

Stolen from WIKI on various over voltage devices

Quote:

A varistor is an electronic component with an electrical resistance that varies with the applied voltage.[1] Also known as a voltage-dependent resistor (VDR), it has a nonlinear, non-ohmic current–voltage characteristic that is similar to that of a diode. In contrast to a diode however, it has the same characteristic for both directions of traversing current. At low voltage it has a high electrical resistance which decreases as the voltage is raised.

Varistors are used as control or compensation elements in circuits either to provide optimal operating conditions or to protect against excessive transient voltages. When used as protection devices, they shunt the current created by the excessive voltage away from sensitive components when triggered.

Similar devices, though usually not functionally interchangeable with SIDACs, are the Thyristor Surge Protection Devices (TSPD), Trisil, SIDACtor®, or the now-obsolete[when?] Surgector. These are designed to tolerate large surge currents for the suppression of overvoltage transients. In many applications this function is now served by metal oxide varistors (MOVs), particularly for trapping voltage transients on the power mains.

Peter.N. · 24th Feb 2016, 12:46 am

And me.

Heatercathodeshort · 24th Feb 2016, 10:02 am

Sparky gappy similar to the ones sometimes discovered in the back of BT master boxes. J.

rovernut · 24th Feb 2016, 11:14 am

Hi

Thanks for the replies, as soon as spark gap was mentioned, I knew I had seen one before.

The PSU for the T1000 is overly complicated and has many interlocks and this is the second level of voltage protection. On this board there is also an antisurge dropper resistor that get shorted out shortly after the PSU is up and running

See http://www.samhallas.co.uk/repositor...000_manual.pdf

for more info

Cheers
Richard

23rd Feb 2016, 10:10 pm	#1
rovernut Pentode Join Date: Oct 2010 Location: Fareham, Hampshire, UK. Posts: 112	Is this a varistor ? Hi Is this component a varistor ?, it has a Seimens logo and 600 marked on the end, physically it is about 6mmin diameter and about 5mm long. It is off a PSU for a Seimens T1000 teleprinter, that I and trying to get going Any information would be useful and how can I test it ? Cheers Richard Attached Thumbnails

23rd Feb 2016, 10:14 pm	#2
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,879	Re: Is this a varistor ? looks like a lightening protector (spark Gap) It should read open circuit until you exceed its protection voltage. Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk

23rd Feb 2016, 10:56 pm	#3
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,433	Re: Is this a varistor ? Looks like a spark gap to me as well. Frank

24th Feb 2016, 12:46 am	#5
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: Is this a varistor ? And me.

24th Feb 2016, 10:02 am	#6
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Is this a varistor ? Sparky gappy similar to the ones sometimes discovered in the back of BT master boxes. J.

24th Feb 2016, 11:14 am	#7
rovernut Pentode Join Date: Oct 2010 Location: Fareham, Hampshire, UK. Posts: 112	Re: Is this a varistor ? Hi Thanks for the replies, as soon as spark gap was mentioned, I knew I had seen one before. The PSU for the T1000 is overly complicated and has many interlocks and this is the second level of voltage protection. On this board there is also an antisurge dropper resistor that get shorted out shortly after the PSU is up and running See http://www.samhallas.co.uk/repositor...000_manual.pdf for more info Cheers Richard