What are the measurements of electricity

Measuring electrical quantities

measure up

Measuring means comparing an unknown quantity with a known quantity.

Measurand

In electrical measurement technology, current, voltage and resistance are referred to as measurands. The measured variable is the unit of the measured value.

Measured value

A value is determined during the measurement. It is called the measured value. This is made up of the display value and the measured variable. The measured variable is the unit.

Display value

The display value is determined from the pointer deflection of an analog measuring device or read off from the display of a digital measuring device.

Measuring range

Since the measured value can be very large or very small and, due to its structural size, a measuring device only has limited space to display the measured value, the measuring range is set before the measurement. To do this, you have to know roughly how high the measured value could be beforehand. As a rule, you start with a high measuring range and, if necessary, switch down the measuring range step by step.

Zero position

When zeroing without applied voltage or current, the pointer must be exactly above the zero line on the scale. If not, then the pointer has to be adjusted. Otherwise there will be a measurement error.

Measuring device

The measuring device is used to determine the measured value, the numerical value, an electrical variable (measured variable).

Basics about measuring

  1. Never measure twice. Because otherwise you won't know which of the two results is the right one.
  2. All constants are variable.
  3. Who measures, measures dung.

In view of the measurement result, the measurement must always be viewed critically. If a measurement is carried out incorrectly, all kinds of values ​​can be measured. This means that measurement results always have to be interpreted correctly.

Questions before the measurement

Even if it is a simple standard measurement, you should ask yourself the following questions before measuring:

  • Which measured value do I need with which accuracy?
  • How many decimal places do I need?
  • I measure direct voltage (DC), alternating voltage (AC) or a voltage with an alternating voltage component (AC).

Depending on the answer, the measuring instrument is to be selected, the measuring range to be set and the type of measurement to be used (e.g. current error and voltage error circuit).

Measurement error

Various errors can occur when determining the measured value. In order to rule out these errors, the following points must be observed:

  • Note the position of use of the measuring device.
  • Measuring instruments are sensitive and should therefore be handled with care.
  • Measuring instruments should not be exposed to excessive temperatures.
  • With analog measuring devices, the last third of the measuring scale should be used.
  • Magnetic fields influence the measuring mechanism.
  • Measuring devices are to be stored dry and free of dust.
  • Pay attention to the measurand and measuring range when measuring.
  • On measuring instruments, check the zero position of the pointer before measuring.

In order to keep the measuring error as small as possible with the analog measuring device, the measuring range (switch position) should be selected so that the pointer is in the last third of the scale.

Overview: electrical measuring devices

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