×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

overvoltage capability of appliances/TV sets

overvoltage capability of appliances/TV sets

overvoltage capability of appliances/TV sets

(OP)
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?    

RE: overvoltage capability of appliances/TV sets

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.

RE: overvoltage capability of appliances/TV sets

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

Keith Cress
kcress - http://www.flaminsystems.com

RE: overvoltage capability of appliances/TV sets

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

RE: overvoltage capability of appliances/TV sets

(OP)
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.

RE: overvoltage capability of appliances/TV sets

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

Keith Cress
kcress - http://www.flaminsystems.com

RE: overvoltage capability of appliances/TV sets

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.

RE: overvoltage capability of appliances/TV sets

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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources