Here's a link to Dell's comments on using laptops in different countries to quote from there
"Different countries use power supplies at different voltages (usually 110 V or 220-240 V) and AC frequencies (usually 50 Hz or 60 Hz). Most Dell AC adapters can operate between 100 VAC to 240 VAC (Volts Alternating Current) and can operate effectively across different locations.
The label on the back of the AC adapter brick specifies the input voltage range of the adapter.
CAUTION: The AC adapter provided with your Dell laptop works with electrical outlets worldwide. However, the power cable might not be compatible with the power sockets available in another location. Using an incompatible power cable or improperly connecting the power cable to an electrical outlet may cause a fire hazard or damage the device.
NOTE: When traveling, check the type of power sockets that are used in the location you are traveling to. You can use universal travel adapters that help you connect the power cable to the power socket in multiple locations. Dell does not sell these, but you can buy these at many electrical retail stores or supermarkets. You can find more information about power sockets, plugs, and voltages in this Wikipedia Article - Mains electricity by location
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Hope this is useful