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Power Quality FAQs

  • How to Choose Transformers
  • How to Choose Transformers is an important area to consider when you begin the journey toward a transformer investment. How to Choose Transformers begins by determining the transformer’s capacity which is rated in volts-amps (VA). Operational voltage for most appliances and/or equipment should be visibly labeled as follows:
  • Current (Amps), Frequency (Hz), Voltage (Volts), Wattage (Watts or VA)
  • This voltage labeling is usually located on the back of the appliance. If labeled voltage cannot be located, it is fine to use the wattage in most cases. If the appliance labeling shows starting amps and running amps, it is best to use the running amps to calculate the wattage (VA).
  • How to Choose Transformers continues with the result of a basic Voltage x Amps calculation. With the resulting number, you now know How to Choose Transformers--with a VA rating equal to or larger than the VA listed on the appliance. It is always fine to use a transformer with a larger VA listing but using a transformer with a smaller VA rating could lead to overheating and/or burning out the transformer, which is not advisable.
  • In general, it is more cost effective to use one large transformer for several appliances than to have several transformers for each appliance. However, if you have an appliance that is frequently running (washing machine, freezer, etc.) and the transformer is permanently placed, that transformer should be left attached and dedicated solely to that one appliance.
  • What is harmonics
  • Harmonics are electric voltages and currents that appear on the electric power system as a result of certain kinds of electric loads. Harmonic frequencies in the power grid are a frequent cause of power quality problems.
  • Causes
  • In a normal alternating current power system, the voltage varies sinusoidally at a specific frequency, usually 50 or 60 hertz. When a linear electrical load is connected to the system, it draws a sinusoidal current at the same frequency as the voltage (though usually not in phase with the voltage).
  • When a non-linear load, such as a rectifier, is connected to the system, it draws a current that is not necessarily sinusoidal. The current waveform can become quite complex, depending on the type of load and its interaction with other components of the system.
  • Regardless of how complex the current waveform becomes, as described through Fourier series analysis, it is possible to decompose it into a series of simple sinusoids, which start at the fundamental power system frequency and occur at integer multiples of the fundamental frequency (as described in the main harmonic article).
  • What is power quality?
  • Power quality means different things to different people, but it is generally an all-encompassing term used to describe the consistency and desirable characteristics, or lack thereof, of electrical power from its generation, delivery and usage. In nearly all cases, power quality is synonymous with voltage quality.Read more about power quality.
  • What are power quality problems?
  • For most people, power quality problems are anything related with electric power that interferes with the proper operation of their electrical devices. There are numerous specific types of power quality problems, each with their own causes and effects. Read more about power quality problems.
  • What causes poor power quality?
  • The causes of poor power quality run the gamut from squirrels or hot summer days to the failure of equipment on the electric utility’s system. Some causes can be corrected or eliminated while many others are out of anyone’s control, at any price. Read more about the causes of poor power quality…
  • What are the symptoms of poor power quality?
  • The symptoms of poor power quality can be as subtle as motors that prematurely fail every few years or as obvious as equipment that shuts down or as catastrophic as burned out circuit boards.
  • How do I fix a power quality problem?
  • Solutions to power quality problems are dictated by 1) the cause of the problem and its effect, 2) to what extent the problem needs to be corrected, and 3) most importantly, the financial value of correcting the problem. There is no single solution to any power quality problem, but the first and most critical step is to understand the problem and it’s effects. Read more about correcting power quality…
  • Isn’t the electric utility responsible to fix my power quality problems?
  • Yes and no.
  • Yes - as long as they, the utility, are the cause of the problem and it is within their capability to fix it. But, electric utilities are only required to provide power within a broad set of limits.
  • No - the electric utility can’t and won’t take responsibility for problems that are outside of their control or are acts of nature, God, etc.
  • The long and short of the matter is that most electric utilities deliver power as they are required to do: nothing more and nothing less. It is very easy to determine if a problem is the fault of utility, which it rarely is. The vast majority of the time, power quality problems arise due to situations and conditions downstream from the electric meter (where the utility's responsibility ends).
  • What types of power quality problems do MODERN products address?
  • MODERN produces a unique line of products to solve a broad range AC voltage problems for commercial and industrial applications. Sizes range from 3 to 2,000 kVA and up to 600 volts. Chronically high, low or fluctuating voltages, deep voltage sags, unbalanced voltages and unbalanced currents are just some of the power quality solutions provided by MODERN. Read more about Modern products...
  • Can you help me with my power quality problem?
  • Call us. We will be happy to help you find a solution to your power quality problem. Even if we don’t have a solution within our product line, we will do our best to point you to someone who does.