A voltmeter is an instrument used for measuring electric potential difference between two points. It has a high resistance so that it takes negligible current from the circuit.
The M 220B combines the ease of use of a digital voltmeter with the high input impedance and low input capacitance of a true electrostatic voltmeter in a small, portable, battery operated package. Being a true electrostatic voltmeter, not a field meter means that it reads actual voltage, without confusing it with electrostatic field strength, which is quite different.
Many applications require the measurement of a voltage or electrostatic charge on surfaces. Electrostatic charges can buildup during handling, manufacturing, assembly and other operations that can impact production capacity and quality.