AC Current Meters

AC Current Instrumentation

Last month’s posting covered the popular methods for sensing AC current (shunt, current transformer, Hall sensor, Rogowski coil). Here we will review some of the instruments available for fixed, portable, local and remote AC measurements. (more…)

AC Supply

AC Current Measurement Methods

There are two general methods for measuring ac currents:

  • by direct connection with the current-carrying circuit
  • by utilizing the magnetic field or flux generated by the current

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Measurement Display

Display Resolution Is Not Accuracy

Casual users of digital instrumentation often assume that more resolution on the display provides a more accurate measurement – that an extra digit in the readout gives a decade improvement in accuracy. This is rarely the case. (more…)

sensor output

Which Sensor Output is Best?

Industrial sensors for pressure, flow, temperature, position and other process parameters typically include signal conditioning that generates a dc output. This output can be either a voltage or a current. Which output is best for a particular application depends on several factors. (more…)

Inductive Load

Relay Contact Protection

Many digital panel meters include electro-mechanical relay outputs to control external devices. Protecting relay contacts from excessive voltage and current is important to achieving the long operating life that digital instrumentation is designed to provide. (more…)