Voltage measuring instruments are targeted to read specific voltage levels. A meter designed to read up to 240 volts cannot read high voltage lines, which can run at 50,000 volts or more. Engineers are aware of this and design meters to read within a specific voltage range. For instance, the Hipotronics Corporation manufactures a variety of high voltage meters. The highest rated meter is the KVM400, which can measure voltage levels up to 400,000 volts.
AC voltage reverses polarity constantly. In household current, this occurs at 60 times per second, commonly referred to as "60 Hertz (60 Hz)." A Hertz is a measurement of frequency. It measures how many times an electrical waveform pulses in one second. Meters designed for home use are calibrated to read the voltage at 60 Hz. Other meters are designed to read AC voltages at different frequencies, such as 50 Hz. This frequency is commonly found in Europe, according to Professor Richard Fitzpatrick at the University of Texas in Austin. It's important to note that using a meter calibrated for one frequency will give an inaccurate reading when trying to measure another AC frequency.
Some voltmeters have storage capabilities. The voltages you read are stored in memory and can be brought up for analysis later. Sometimes you need this kind of meter. The voltage pulse may last only a microsecond, and the meter has to capture and store the pulse. Other specialized meters have the capability of measuring and storing voltage leakage through an insulator, such as the High Voltage Insulation Tester manufactured by the Hioki E.E. Corporation.
Thousands of different meters exist, each with their own unique size. Many simple meters are small handheld units, but storage and other sophisticated meters are usually bench mounted. It's really up to you to determine which meter fits the application. Bear in mind engineers and technicians are not concerned with the aesthetics of a meter. Their only concern is functionality. A very powerful meter may be housed in a plain looking case.