Something doesn't seem right at all. Laptop adapters are usually DC and nominally around 45-90 watts. 30 VAC at 0.5 amps means 15 watts, which doesn't make any sense.
120 VAC at 500 mA would translate to 60 watts and 30 VDC, not AC is likely.
Check the specifications again. Some Dell Adapters are located here:
Dell Inspiron AC Power Adapters
You can also post a model number.
Many adapters are usually universal, meaning they will accept 95-285 VAC. The only requirement is to change the input power cord to the country of origin.