Types of Power Supply Problems and How to Solve Them

Here we explain common power issues, and how Claude Lyons can assist you in resolving them.

Voltage Dip or Sags

Sine Wave diagram of Over Voltage Sags

Diagram showing the sinewave of a typical voltage dip, also known as voltage sag

Voltage Swells

Sine Wave diagram of Voltage Swells

Diagram showing the sinewave of typical voltage swells

  • What is a Voltage Swell?
    Voltage swells are the opposite of dips and describe surges in voltage of 10% or more above normal or recommended usage.
  • What is the definition of a Voltage Swell?
    Voltage Swell is defined by IEEE 1159 as the increase in the RMS voltage level to 110% – 180% of nominal, at the power frequency for durations of ½ cycle to one (1) minute.
  • What are the symptoms of a Voltage Swell?
    They can cause long term problems with machinery and overall power quality in a plant and ultimately lead to system failure.
  • What causes Voltage Swells?
    Voltage Swells are typically due to large loads switching off, resulting in a sudden change in load impedance which can cause the voltage to swell. These loads can include such things as large motors, furnaces and large welders.
  • How do I solve Voltage Swells?


Sine Wave diagram of under voltage

Diagram showing the sinewave of a typical undervoltage

  • What is a Under Voltage?
    Undervoltage occurs when the average voltage of a power system drops below intended levels for more than 1 minute.
  • What are the symptoms of a Under Voltages?
    Common symptoms of undervoltage can include motors run hotter than normal and fail prematurely, dim incandescent lighting and batteries fail to recharge properly.
  • What causes Under Voltages?
    Undervoltage often occurs from low grid distribution voltage because of heavily loaded circuits that result in considerable voltage drop, switching on a large load or multiple loads, or a large capacitor bank switching off.

Surges and Overvoltages

Sine Wave diagram of Over Voltage and Surges

Diagram showing the sinewave of  typical surges and overvoltages

  • What are Surges and Over Voltages?
    Surges, or transients, are brief overvoltage spikes or disturbances on a power waveform that can damage, degrade, or destroy electrical/electronic equipment within any home, commercial building, industrial, or manufacturing facility.
  • What is the definition of Surges and Over Voltages?
    A sudden increase in voltage that lasts for three nanoseconds or more is called a voltage surge.
  • What are the symptoms of a Surges and Over Voltages?
    Systems that incur power surges or over voltages can lead to premature system failure. High voltages causes additional stress to components and leads to degradation over time, ultimately leading to failure.
  • What causes Surges and Over Voltages?
    Power surges or over voltages are often caused either by lightning impulses or switching impulses within the system, for example a large load switched off.
  • How do I solve Surges and Over Voltages?


Sine Wave diagram of Voltage Brownout

Diagram showing the sinewave of a typical voltage brownout

  • What are Brownouts?
    A brownout happens when the voltage drops below the usual mains supply level. It is similar to a sag; a short-term drop in voltage, but can last for anywhere between a few minutes or even several hours and days.
  • What is the definition of Brownouts?
    A power brownout is an intentional or unintentional drop in electrical power supply. A brownout can last a few seconds through to hours or even days in some severe cases.
  • What are the symptoms of a Brownouts?
    Complete loss of power of systems, both mommeturly and also for sustained period of time. Short brownouts can cause equipment to restart/reset.
  • What causes Brownouts?
    Large industrial equipment being switched on, switching of the mains supply or powering of large motors. They can be caused by the incoming source failing or intentional brownout for load reductions in emergency.
  • How do I solve Brownouts?

High Voltage Spikes

Sine Wave diagram of high voltage spikes

Diagram showing the sinewave of typical high voltage spikes

Electrical Noise

Sine Wave diagram of Electrical Noise

Diagram showing the sinewave of a typical electrical noise

  • What is Electrical Noise?
    Electrical noise is the result of more or less random electrical signals getting coupled into circuits where they are unwanted.
  • What is the definition of Electrical Noise?
    In electrical system, noise is an unwanted disturbance in an electrical signal, Noise generated by electronic devices varies greatly as it is produced by several different effects.
  • What are the symptoms of Electrical Noise?
    There are lots of different types of electrical noise, typical symptoms of electrical noise include systems lock up, system resets, damaged PCB’s, disruption to visual or audio equipment.
  • What causes Electrical Noise?
    Electrical noise can come from within the system itself (internal noise), where it can be caused by faults in switchgear or from the electrical design itself.

    External electrical noise includes lightning and electrical storms, electromagnetic interference from currents in cables, and frequency interference from equipment like RF transmitters or microwave radiation.

  • How do I solve Electrical Noise?

Electrical Blackouts

Sine Wave diagram of Black outs

Diagram showing the sinewave of a typical voltage blackout (lasting one complete cycle)

  • What is the definition of Blackouts?
    The definition of an electrical blackout is when complete failure of the electricity supply, lasting from a few seconds to multiple hours, days.
  • What are Voltage Blackouts?
    When total failure of the incoming electrical supply occurs within electrical systems, also known as mains failure.
  • What are the symptoms of Blackouts?
    Complete loss/operation of systems, blackouts may only last factions of a second, but are sufficient to cause equipment to reset or crash.
  • What causes Blackouts?
    There are multiple causes of power outages causing blackouts, these can include; faults at power station, damage to electric transmission lines, substations or equipment failure such as fuse/circuit breaker.
  • How do I solve Blackouts?
    Popular solutions to Blackouts include;

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