HOW TO CHECK BLOWN FUSES & CAPACITOR CELLS

In Fixed Power Factor Correction Capacitors

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Trouble: Fuse light is illuminated.

  • This indicates that a fuse is blown. Power surges or harmonics are two common causes of fuse failure.
  • Disconnect power from the capacitor unit and wait one minute after the power has been disconnected to allow capacitors to discharge.
  • Check affected capacitor following steps below: How to Test a Capacitor Cell
  • Replace affected fuse.

Trouble: Amber light is illuminated in KIM model PFCC

  • This may indicate that a fuse is blown or the capacitor has lost capacitance.
  • Check amperage draw of capacitor unit while it is connected to power based on following table. If the amperage is low complete the next three steps.
Applied Voltage
208V
240V
480V
600V
Amps / kVAr
2.78
2.41
1.20
0.96
  • Disconnect power from the capacitor unit and wait one minute after the power has been disconnected to allow the capacitors to discharge.
  • Check the fuses using an ohmmeter. Replace any blown fuses.
  • Check the capacitors following steps found in steps below: How to Test a Capacitor Cell
  • Replace bad capacitor cells.

How to Test a Capacitor Cell:

With a Capacitance Meter

Capacitor cells are rated in microfarad and voltage. The easiest way to test a cell is to measure the microfarads with a capacitance meter.

  1. Disconnect power from the capacitor unit and wait one minute after the power has been disconnected to allow the capacitors to discharge.
  2. Measure microfarads using capacitance meter. The microfarads should be equal to the microfarad rating or up to 5% over the rating. This microfarad table may be used as a reference.
  3. If microfarads are below the minimum, the cell is going bad.
  4. Replace bad capacitor cells.

Visual Inspection of Cell
If a capacitor meter is not readily available, the status of a cell can sometimes be determined visually.

  1. If the cell can is “bulged out” or “pouched up” on the top, it is definitely bad.
  2. Disconnect power from the capacitor unit and wait one minute after the power has been disconnected to allow the capacitors to discharge.
  3. Replace bad capacitor cells.
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