While Power Factor correction capacitors can effectively reduce industrial energy consumption for as long as 10 and 20 years, failure modes and the ideal operation of power capacitors can be hampered by several factors.

Understanding Power Factor Correction, the failure modes of power capacitors and how to support the overall lifespan of power factor correction equipment will assist industrial operations to cut back on electrical consumption and initiate sustainable energy efficiencies in the long term.

A typical mode of failure for Power Factor correction equipment can be attributed to the gradual deterioration of the polypropylene film, because of general wear and tear or ineffective heat dissipation.  Power capacitors have typical dissipation losses of 0.25W/kVAr.  Effective ventilation of power capacitors assists in optimising the life expectancy of the polypropylene film, preventing the premature failure of the capacitor.

Well-designed Power Factor Correction capacitors are fitted with a pressure disconnect device which helps prevent the catastrophic failure of the capacitor due to an overpressure condition following the development of a “Hot Spot” inside the capacitor.

Other causes of failure of Power Factor Correction capacitors can be attributed to the following external and design factors:

  • Elevated ambient and operating temperatures as well as elevated humidity levels
  • Elevated harmonic levels
  • Voltage surges
  • Damage to the Power Factor correction unit during manufacturing, transportation or installation
  • Incorrect installation of the capacitor
  • Type of filling material used, affecting the transfer of heat losses: resin & oil versus gas
  • Use of plastic instead of aluminium casing material
  • Inferior quality of the polypropylene film
  • Incorrect dielectric medium used

Power Factor Correction capacitor have a finite life, typically between 10 and 20 years, but there are many premature and “catastrophic failure modes” that may occur, such as:

  • Fire Damage
  • Exploding Capacitor

Fire Damage to a Power Factor Correction Capacitor with a plastic housing

The development of a “Hot Spot” inside a Power Factor Correction capacitor can have catastrophic consequences.  When a “Hot Spot” grows, both in size and temperature, so too does the generation of gaseous pressure and compounded heat. In capacitors with a plastic housing (as opposed to an aluminum housing) and without a functional pressure disconnect device, the “Hot Spot” expands and may reach the plastic housing of the capacitor, eventually burning through the plastic casing. Once the hot spot is exposed to oxygen it can self-ignite, resulting in a fire that not only damages the capacitor but surrounding hardware and peripheral equipment too.



An Exploded Power Factor Capacitor

Under certain circumstances, Power Factor capacitors without a functional over-pressure disconnect mechanism, may become so pressurized when they are in the process of failing, that the capacitor housing cannot contain the pressure build-up within the unit and it explodes. In cases where the PF correction capacitor casing is not correctly sealed, the over-pressure disconnect mechanism cannot operate when the capacitor is in the process of failing and this can also result in the unit exploding.

Alpha Power PF correction capacitors can reduce the total current drawn from an electrical distribution network in industrial operations, commercial businesses and factories, ensuring that electrical equipment fitted to a plant converts energy as efficiently as possible.

 Power factor (PF) correction can:

  • Increase systems capacity
  • Reduce utility expenses
  • Reduce power transmission losses

For professional Power Factor efficiency inspections, a PF audit report and optimised Power Factor capacitor installations, contact Alpha Power Solutions for customised power solutions.