Electrostatic voltmeter

The electrostatic volt meter, also referred to as an electrostatic voltmeter, an electrical power meter which operates according to the electrostatic principle. The measurement is fed back to the physical size of a motor.

To more efficient contact measuring method of the electric voltage and the electric field intensity, see also electrometer amplifier, as well as rotation voltmeter.

General

The method utilizes the force of which is found on electric charges in Coulomb's law expression. The force fields on the electric charge on the electrodes is at equilibrium equal to the spring force Fspring which serves the provision:

Where d is the pitch of the electrode, A is the area of ​​the electrodes, ε0 is the dielectric constant and D is the spring constant. The displacement x is visualized on a scale and provides an expression for the applied electrical voltage U dar.

With DC voltage, the display is independent of the polarity with AC voltage, the effective value is displayed due to the mechanical inertia, detection of impulse voltages, however, is not possible. A relatively high accuracy of up to 0.1 % of the quadratic voltage dependence of the force equation is given only at high electric voltages according to. By varying the distance d of the sensing electrodes, the voltage range can be chosen within certain limits.

Species

Strong -Schröder voltmeter

In the strong -Schröder voltmeter is electrostatic voltmeter, which is used in high voltage engineering. In this case, by the electrostatic force effect a small mirror is moved on one of the electrodes, which deflects a light beam. This deflection, which is proportional to the voltage may be read on a scale.

Strong -Schröder voltmeter be performed in a simple design up to voltages of a few 10 kV. At high voltages in excess of 100 kV, pressure gas-insulated embodiments, in order to keep the physical dimensions of the electrodes, and edge effects from parasitic effects, according to small, are used. These instruments, because of their mechanical sensitivity usually only in the field of high voltage laboratory used.

Electroscope

→ Main article: electroscope

In the electroscope both electrodes are at the same potential and repel each other when voltage is applied from each other, wherein an electrode is formed as a pointer and the display is. The strength of the electrostatic repulsion of the electrodes is in some devices by the force applied to the pointer in the gravity balance.