‧ Automatic Capacitor Bank Wiring Diagram

‧ Installation of Capacitor Expulsion Fuse
‧ Capacitor Expulsion Fuse Unit

Electrical Properties of Metallized Film

Capacitance Change vs. Temperature

Insulation Resistance vs. Temperature

Dissipation Factor vs. Temperature

MPET: Metallized Polyester Film

MPP: Metallized Polypropylene Film

Self-healing mechanism

Dielectric adopts metallized film as intermediate; in case excessive voltage takes place and damages the material, the metallized layer around the damaged spot will disappear instantly, and insulation is restored immediately.

  1. Metallized layer
  2. Film
  3. Damaged spot
  4. Self-healing range


Operation of Internal Safety Mechanism

Capacitor element wounded by segmented metallized film. Hundreds or thousands of small capacitors in parallel formed the element, and each small capacitor equipped individual fuse as Figure 1. When a dielectric breakdown occurred in a small capacitor due to overvoltage, abnormal heating or end of life, the fuse of the failure area burned off and disconnected the failure area from circuit. The remained good small capacitors would continue to be used as Figure 2. Capacitor will not lose the function caused by partial failure. Its self-protective function will prevent capacitor from emitting smoke or catching fire.

Figure 1. Element Structure (Normal Condition)
Figure 2. Fuse burned off on failure area
  1. Segmented metallized film
  2. General metallized film
  3. Metallized layer
  4. Free margin in transverse direction
  5. Free margin in machine direction
  6. Fuses
  7. Failure area
Operation of Internal Protective Device

In the event of internal failure or aging at the end of the capacitor's operational life, an increasing number of self-healing breakdowns may cause rising pressure inside the capacitor element. To prevent it from bursting, each capacitor element is designed with internal pressure sensitive interrupter (Protective Device). With rising pressure the cover will bulges to disconnecting copper taps at weak points from the cover, and the current path is interrupted irreversibly to avoid the relative disaster.

Contents of Capacptor Technical supports
Capacitor function Notices for capacitor installation
The benefits of shunt capacitors References for selections of protective devices for low voltage capacitors
The benefits of shunt capacitors at different location Capacitor maintenance
Selection principles of power factor correction capacitors for industrial high or low voltage power system Calculation of power factor correction
Harmonics strategies of power capacitors General formulas
Calculation of resonance point and frequency on capacitors with serial reactors Calculation of discharging resistor for capacitor
Instruction for power capacitors Features of low voltage power capacitors
The causes of capacitor faults Heat dissipation instruction for induction heating furnace capacitors
The effects of lightning strikes on capacitors Circuit diagram for automatic PFC capacitor banks
Correct connection of capacitor for star-delta starting induction motors The parts and dimensions of expulsion fuses for power capacitors