The range and complexity of electrical equipment has increased dramatically in recent years. An unwanted consequence of this rise is the creation of harmonic currents, which can cause voltage distortion and quality problems. Also known as damping resistors, harmonic filters reduce distortions in power systems, which can be produced by nonlinear loads such as arc furnaces and switch-mode power supply (SMPS).
 
Harmonics can have adverse effects on the power supply network. If the nonlinear loads produce unwanted harmonics, they could cause equipment failure as a result of insulation breakdown, arcing and overheating. As such, this aspect of power quality management is of high importance to both suppliers and users of electrical power. Harmonics can be reduced using passive filter circuits, consisting of inductors, capacitors and resistors. The filter circuit allows the fundamental frequency to pass through it while diverting any harmonic frequencies to the resistor bank. Here, the frequencies are dissipated as heat and are removed from the system.
 
An essential consideration when choosing a harmonic filter is that harmonic currents can induce additional heating in generators. Harmonics can also lead to the overheating of busbars, cables and equipment, thermal damage to induction motors and thermal tripping of safety devices such as fuses or sensors in breakers. High power resistors (HPRs) are versatile plate-style resistors, ideal for medium and high-power electric braking, neutral earthing and load testing. HPR grids are flat in shape, meaning they cannot absorb as much current as other types of filter. Users can find many kinds of high power resistors from Microhm Electronics, such as Nual series, LHR series and NLR series.However, this large surface area and high active mass ratio also means that they can cool much quicker.
  After the initial analysis, we can recommend the most appropriate solution and design a resistor specific to your needs. Harmonics aren’t going anywhere, and businesses cannot ignore them. With the right solution in place, we can continue to make the most out of electrical equipment while protecting it from unwanted currents.