Not being able read marking of a part (update: Varistor)

Willen · Feb 13, 2013

The 'A' component used instead of two parallel zenere diode. What is this and which is the value of it?

The 'B' component used here to earth the ground plane. It has CY code and looks like a capacitor. What is the difference between C and CY? What is this?

Timescope · Feb 13, 2013

"A" is a metal oxide varistor, a device that protects a circuit from excessive voltage and voltage spikes from the mains supply. This one clamps at 150v ac or about 220v dc and is usually located after the fuse between Live and Neutral, (Hot and Cold in America), in a power supply.

"B" is a 4.7nF capacitor rated at 2kV.

Timescope

dougy83 · Feb 13, 2013

Willen said:
The 'A' component used instead of two parallel zenere diode. What is this and which is the value of it?

MOV: https://en.wikipedia.org/wiki/Varistor

Willen said:
The 'B' component used here to earth the ground plane. It has CY code and looks like a capacitor. What is the difference between C and CY? What is this?

4.7nF 2kV capacitor connects from ground to some point on the isolated side of the transformer. It is used for EMI suppression

Willen · Feb 14, 2013

Timescope said:
"A" is a metal oxide varistor, a device that protects a circuit from excessive voltage and voltage spikes from the mains supply. This one clamps at 150v ac or about 220v dc and is usually located after the fuse between Live and Neutral, (Hot and Cold in America), in a power supply.

Did you mean the varistor will make short circuit at 150V AC? (to burn out the fuse instead of valuable device)

Timescope · Feb 15, 2013

Willen said:
Did you mean the varistor will make short circuit at 150V AC? (to burn out the fuse instead of valuable device)

Exactly. Here are some brave varistors that sacrificed themselves to save the rest of the supply when high mains voltage was present.

Timescope

audioguru · Feb 15, 2013

An electrical surge arrestor was sold with a window that showed the MOV. It was labelled, "When it turns black then send it back".

Willen · Feb 16, 2013

audioguru said:
An electrical surge arrestor was sold with a window that showed the MOV. It was labelled, "When it turns black then send it back".

With window??? Window of house?? Confused! To protect from lightning surge?

bryan · Feb 16, 2013

Meaning there was a clear window over the MOV. When it was blown by a surge or lightning it would turn black, signaling the owner it needed to go in for repair as it is no longer protecting.

audioguru · Feb 16, 2013

All the wiring is underground in my neighbourhood so lightning doesn't come here.
There are a couple of condo apartment buildings with 30 floors about 1km away that get hit with lightning during every storm.

But they never got hit by a meteorite or asteroid (yet). Yesterday Russia got blasted!

Willen · Feb 16, 2013

audioguru said:
All the wiring is underground in my neighbourhood so lightning doesn't come here.
There are a couple of condo apartment buildings with 30 floors about 1km away that get hit with lightning during every storm.

But they never got hit by a meteorite or asteroid (yet).

How funny! Hahaha
I have never seen such lighting discharg on taller buildings or hills or on towers! There are no taller building around me! Few people are burning themself by lightning strike on every storm (every rainy season) during April June around my area. I think I need a varistor to protect myself too.

Yesterday Russia got blasted!

What? Which? How?

audioguru · Feb 16, 2013

Willen said:
What? Which? How?

I watch the news on TV every day.
Yesterday a meteorite exploded over Russia and injured 1200 people and destroyed many buildings from the pieces and the sonic BOOM noise. https://www.cbc.ca/news/world/story/2013/02/15/russia-meteorite.html

A few hours later a huge asteroid flew past earth very close. https://www.cbc.ca/news/technology/story/2013/02/14/science-asteroid-da14-flyby.html

audioguru · Feb 16, 2013

*****

killivolt · Feb 16, 2013

Struck by lighting in the U.S. Deaths and Injured.

http://http://www.struckbylightning.org/

2012

2011

2010

2009

2008

Willen · Dec 9, 2016

Hi again,
And now can you help me to read its marking? Can you tell me the clamp voltage of each of these varistors?

vtech · Dec 9, 2016

Deciphering the numbering system will take some time to get used to since it is not exact.
As a rule of thumb, usually the first digit is indicative of the diameter of the device (not always). the rest of the numbering may or may not be exact either;
If possible, the best way is to look at the logo first and go from there or possibly use a cross reference chart;

The Orange one has the old SGS-Thompson logo
Blue one is EPCOS/Siemens/TDK
Last one has the Panasonic (Matsushitsa) logo. ERZCO prefix was used by Panasonic.
Look at this cross reference PDF file, it will give you an idea;
https://www.chipfind.net/datasheet/pdf/ceramate/crossreference.pdf

Willen · Dec 10, 2016

Thanks vtech, However it's strange that why the marking of varistor is so complicated always!

hyedenny · Dec 10, 2016

Not as strange as the 3.75 year gap between your replies!

davenn · Dec 10, 2016

vtech said:
Deciphering the numbering system will take some time to get used to since it is not exact.
As a rule of thumb, usually the first digit is indicative of the diameter of the device (not always). the rest of the numbering may or may not be exact either;
If possible, the best way is to look at the logo first and go from there or possibly use a cross reference chart;

The Orange one has the old SGS-Thompson logo
Blue one is EPCOS/Siemens/TDK
Last one has the Panasonic (Matsushitsa) logo. ERZCO prefix was used by Panasonic.
Look at this cross reference PDF file, it will give you an idea;
https://www.chipfind.net/datasheet/pdf/ceramate/crossreference.pdf

outstanding
thanks for that

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