110V equipment subjected to 220V?

[EEC]

Equipment being television, mircowave, refrigerator and others like that. What actually happens to this equipment being subjected to 220V, thats 110V on the Black wire and other 110V on the white wire? What's the electrical theory behind your response as too what occurs? Also if damage occurs is the equipment totally loss?

 

[Dennis Alwon]

In generally you will blow out the electrical components of a TV or any electronic equipment that is rated 120V . Put 240V to a 120V light bulb and the filament will break.

 

[Strathead]

Equipment being television, mircowave, refrigerator and others like that. What actually happens to this equipment being subjected to 220V, thats 110V on the Black wire and other 110V on the white wire? What's the electrical theory behind your response as too what occurs? Also if damage occurs is the equipment totally loss?

There are way too many components to answer your question specifically or with theory. I many cases, you will get twice the current flow, because the resistance is constant and ohms law, E=IxR states that current is directly proprtional to current. Double current causes overheating, which in turn lets the smoke out.

 

[Dennis Alwon]

I will admit that I once wired a split system heating system with 240V. I had never seen an outdoor unit that was 120V so... Amazingly the system worked but I assume damage was done since a outdoor part had to be replaced 6 months later. It never affected the indoor motor.

 

[charlie b]

There are two theory-related answers to this question. One has already been mentioned, that you will get double the current, and therefore double the heating effect of current flow. So the device could fail due to overheating. The other answer is that the voltage rating of any electrical component is based on the ability of its insulation system to prevent leakage of current from the internal current-carrying parts to the exterior metal parts, or to the outside world. Too much voltage will cause leakage current, and that can lead to failure.

On the other hand, if the equipment can handle the extra heat, and if its insulation system is good enough, you might not see a failure for a long time, as Dennis pointed out.

 

[EEC]

Power supply boards

Power supply boards

In most appliances there are power supply boards with leads to various componets of the equipment. Question is can you look at these schematics and determine where the problem parts are from applying 240 volts to a 120 volt power supply?

 

[jmsokol]

There are way too many components to answer your question specifically or with theory. I many cases, you will get twice the current flow, because the resistance is constant and ohms law, E=IxR states that current is directly proprtional to current. Double current causes overheating, which in turn lets the smoke out.

Actually, since Wattage = Volts squared divided by Resistance, if you double the voltage and keep the resistance constant, you will quadruple the wattage. So a 100 watt bulb rated for 120 volts will heat with 400 watts of energy at 240 volts. Typically overheating and meltdown of "electrical" components occurs in anything operated at double voltage for more than a few seconds if there's insufficient mass to absorb or dissipate the extra heat. Motors can survive maybe 30 seconds or so of doubled over-voltage, but begin to smell "hot" very quickly, if memory serves.

But electronic equipment is sensitive to something called reverse breakdown voltage. That's because P-N junctions (like in a diode or transistor) are rated for a specific maximum voltage it will survive in reverse bias mode. Exceed that breakdown voltage for even a few milliseconds, and the P-N junctions can go into avalanche mode, where the normally high impedance reverts to a low impedance state. That can create an explosive overheating effect with parts exploding off the circuit boards (ask me how I know this) and capacitors blowing aluminum confetti all over the inside of the chassis. So plugging in something electronic (like a computerized digital TV set) into 240 volts for even a second will generally result in a complete destruction of everything electronic inside. In the old days (like the 70's and 80's) we could replace parts on circuit boards by soldering them in place. But modern electronics use surface mount components such as capacitors, resistors, and integrated circuits, and few (if any) repair shops are equipped for this sort of repair, even if they could get the parts (which they often can't). That implies that plugging any modern gear into 240 volts is a death sentence, and replacement rather than repair the most likely scenario.

There is a class of modern gear that uses switching power supplies rated from 90 volts to 260 volts or so, and that power supply will use almost any voltage you plug it into and create all the correct DC voltages required by the electronics. Much professional audio gear is built this way now, I think because it could easily be used in England on a 240 volt service one week, and in the USA on a 120 volt service the next week. I work for a lot of pro-sound companies, and high-end sound gear is often built this way which can be very handy in our business.

 

[zbang]

Exceed that breakdown voltage for even a few milliseconds, and the P-N junctions can go into avalanche mode, where the normally high impedance reverts to a low impedance state. That can create an explosive overheating effect with parts exploding off the circuit boards (ask me how I know this)

... a power strip with 1N914 diodes stuffed into the slots... (1N4004's are not nearly as impressive as good ol' glass diodes, don't try this in a small room, use the theater's stage)

and capacitors blowing aluminum confetti all over the inside of the chassis.

See above A 5500 uf 200v capacitor makes a nice mess when it goes, but that was inside the UPS.

Ah, the joys of collage life.

 

[fmtjfw]

Also computers

Also computers

Lots of computer gear uses universal power supplies that are rated: 100--250V & 50--60Hz. Some require flipping a little switch which is almost always a little red one with 120/240 exposed depending on the position. Lots, especially portable items, are auto ranging.

I ran a printer on 120V with the switch set to 240V for years.