Jun 15, 2004, 4:17 PM
Post #8 of 17
After reading the replies in this thread and thinking of my own experience here in central Tampico, where the wall voltage regularly hits 140V, I would like to offer the following. This is based on experience and a little prior knowledge.
1.Any item with a "switch mode power supply" is pretty tolerant of wide variations in input power and frequency. This includes most modern TVs, PCs and monitors. Switch mode supplies can be distinguished by the need to produce either very high voltages (such as found in a monitor or TV) or a wide range of high-current power. The characteristic of a switch mode supply is that output voltage is required to be rock steady over a wide range of input power levels. It is possible to blow these units, but difficult as they are usually quite conservatively rated.
2.Anything with a transformer is in danger of being damaged by high power surges but not necessarily by low power brownouts. This includes most lower-end electronics (such as stereos, clock radios etc). The characteristic of a transformer is that output power rises as the input power rises. It is this secondary high voltage that causes the damage. It is wise to protect these items with an outboard voltage regulator.
3. Anything with a directly connected motor or heating element (washers, hairdryers, food processors, stoves, AC units) MAY be damaged if run for extended periods at a higher or lower voltage. If the line voltage is high then a motor will run faster and hotter but if it is too low then a motor will labour and run hot as well and, usually, be more susceptible to damage. Most white goods do not have electronics that may be damaged by voltage spikes.
4.220V AC units, in order to be damaged, would require a spike or surge on both phases simultaneously. This is possible but not likely and damage is not usual. Again, running an AC compressor on high voltage is less likely to cause damage than running it at a lower voltage. I reccomend 220V mini splits or window units rather than 110V as they would be less sensitive to voltage changes - the power requirement being split across 2 supplies rather than 1.
Finally, I run all my workshop power through a 15A variable transformer to keep it in the 115-117V range but this is because I run a lot of voltage-sensitive tube radio gear as well as having transformer driven 240V power supplies. In fact, as I write, the wall voltage is 132V but my workshop is at 114V.