overvoltage capability of appliances/TV sets

[magoo2]

How long would you expect an an appliance or electronic device like a TV or microwave to last due to a sustained overvoltage? I'm thinking of a steady-state voltage in the 2 to 2.5 times normal range.

Have the surge protective devices folks done any work in this area?

 

[REM76]

A surge protective device is designed to protect the connected equipement against very short period (Micro Second) voltage surge. It is not designed to be a voltage regulator.

 

[itsmoked]

2.5 times? I would expect about 1 power line cycle.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

I don't completely agree with itsmoked on this one. I would expect that although some appliances may fail in the first cycle, some would last several minutes and trip the breaker several times before failure. Toasters, electric kettles, and heating appliances.
In high school we used banks of 150 W lights at 173% voltage for lightning effects on stage. The lamps lasted for many minutes.
But I agree with itsmoked in principle.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[magoo2]

I agree with waross that some appliances are much more tolerant to sustained overvoltages than others. I probably should have restricted my question to the more sensitive ones like TV sets, VCR and microwave ovens.

I just found a reference to some work done by Hydro Quebec. They refer to common electrical appliances like TVs, VCRs, digital clocks, answering machines and microwave ovens.

Their summary states:
- for 1 cycle events, most of the appliances were not damaged at voltages less than 250 V (208% of 120 V).
- for 10 cycle and 100 cycle events, most equipment was not damaged at voltages less than 200 V (166% of 120 V).

I suspect the cabability that is being described is largely a function of the internal MOVs in the appliance tested.

 

[itsmoked]

Well yes I was referring to "[red]electronic device like a TV or microwave[/red]", not purely thermal loads like heaters and the like.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ykee]

You could look at the CBEMA curve for some of the electronic loads:

http://www.itic.org/archives/iticurv.pdf

Not sure how useful it would be for your general appliances though.

 

[rtronics]

Magoo2
My experience is that most appliances do not have an MOV in them, bearing in mind that they are usually subjected to cost-reduction engineering.
Also, an MOV subjected to 2* rated voltage will blow up in spectacular fashion.
At 2* rated voltage the usual switcher power supply will definitely blow up in a cycle or maybe two.
In the olden days, when we used transformers and regulators, the damage would be confined to a blown fuse.
Regards,
Ray.