Distribution cabinet capacitor explosion picture

What are some of the failure problems associated with capacitor banks?

Some of the failure problems associated with capacitor banks are already known since they happen often. A few of the failures are traceable to the original source and sometimes that may be difficult to do. In many instances, the final result of a failure may be a catastrophic explosion of the capacitor into pieces or fire.

Why did the capacitor explode?

The capacitor produced a fireball upon explosion. This oil-filled capacitor was located in an enclosed shelf unit with heavy-gauge steel perforated exterior walls. One area of the wall was exploded outward at the capacitor location ( Photo 2 ).

What is a defective capacitor?

Defective manufacture includes not enough fluid in the capacitor, insufficient plate gap or improper sealing of the capacitor housing. Defective design includes improper electrical specification (using the unit at an excessive voltage) or insufficient cooling of the electronic equipment.

What happens if an internal series group of a capacitor fails?

When an internal series group of a capacitor unit fails, the voltage on the remaining internal series groups in the string increases. It is desirable to remove the bank from service when the voltage applied to the remaining internal series groups exceeds 110% of their rated voltage.

What happens if a capacitor plate is exposed to air?

As the capacitor plates become exposed to the air, the dielectric strength of the plate gap decreases, causing a sudden high energy electrical discharge between plates. This discharge has sufficient energy to ignite oil vapor and cause an explosion, albeit a small one.

What happens if a capacitor bank is not damped?

The capacitor banks tend to interact with the source or transformer inductance and produce ferroresonance. This can produce undamped oscillations in the current or voltage, depending on the type of resonance. If the system is not adequately damped, then there is a possibility of capacitance or transformer failure.