Reasons makes capacitor damaged and swelled – How to repair

Definition about Capacitor:

Capacitor is a kind of passive electronic component created by two conductive surfaces and separated by dielectric. When voltage difference on two conductive surfaces is alternating voltage, charge accumulation is dephased than voltage, create impedance of capacitor in alternating circuits.

Capacitor is divided into 2 kinds: DC capacitor and AC capacitor.

Definition about Capacitor

Capacitor is a system of 2 conductors put closer together and separated by an layer insulation (dielectric). Capacitor has charge and discharge in the circuit. Featured quantity for charge ability of capacity at a certain voltage, called capacity of capacitor.

At the moment, there are 2 kind of capacitor: Oil capacitor and dry capacitor, both has strength and weakness each another.

Reasons make capacity damaged and swelled:

Due to connection is not good: This is basic reason, if connection is not certain, contact is not good then it will cause arc, current is not enough power. This is immediately or according to times depend on every level will cause swelling and declining capacitor’s power.

Due to design is incorrect technology: Capacitor voltage is not suitable for system of voltage. When voltage of system is higher voltage of capacitor will cause damaged capacitor or swelling capacitor depend on each level. The size of conductor and component’s power is lower calculated power will generate heat after damaging capacitor.

At the moment, there are some capacitor: 3P 400V, 415V, 440V, 480V, 525V…

Panel’s space is not airy make capacitor been hot, the dust penetrates the poles of the capacitors, contactor and CB, make a bad line, affect the capacitor and technical factor of capacitor.

Due to capacitor is poor quality: On the market today, there are many sorts of capacitor of many of other manufacturer. If we select not good capacitor, after a while, capacitor don’t not only decline power but also make capacitor swelled. In special cases, electrical quantity and dielectric is not good, it can make capacitor damaged.

Today, there are many firm such as: Epcos, Enerlux, Ducati, Schneider, Samwha, Nuintek, Shizuki…

Due to poor electrical quality: ( Changed amplitude and distort: Voltage and current)

Due to changed amplitude:

I.e, change the value of the voltage but don’t change sine waveform of the voltage. When voltage amplitude of system overcomes voltage standard would make capacitor swelled or damaged depend on the change level.

Due to distort of voltage and current:

Due to harmonics of system causes and reduces power quantity of this system. Total of harmonics distortion (THD) of system have 2 factor: Voltage harmonics (THD-V)  and current harmonics (THD-I = TDD) . Harmonics would cause  distort for voltage and current of system.

Definition of harmonics filter reactor

Harmonics filter reactor is a noisy form, featured by complete vibration on basic industrial spectral frequency. Harmonics filter reactor in AC power is definited as sin of a wave period with frequency is equal with integer times of basic frequency in that system.

fh = h.fb; h = (n*p) ± 1, in that, h is harmonic step, n is positive integer, p is impulse number ( 3, 5, 7, …,21,…49, …)

Analyzing Harm of Harmonics

There are system of harmonics, voltage is relatively stable, but harmonics of current is very high. There are special harmonicses, cause searing voltage, make Trip CB, MC damaged, make capacitor damaged.

There are system of harmonicses has high preasure, this leads to current flow through capacitor is veery high, make capacitor damaged.

Zc = 1/ (C*w) = 1/ (C*2*), Due to  Zc inversely proportional to f thus I increase

Vrms =    =   = V1*,

THD-V = Vthd% = (Vh/ V1) *100%

Irms =  =   = I1*,

THD-I = Ithd% = (Ih/ I1) *100%

Harmonic resonance:

Resonance in electronic is resonance of LC circuit, devided into parallel and serial resonance. Both will appear when has high number harmonics. Parallel resonance made over current and serial resonance made over voltage. If resonance’s amplitude of voltage and current is big enough is capacity panel and another electric devices will be severely damaged.

Resonance frequencies (passive): f = 1/ (2*pi*)

How to overcome capacitor’s damaging and swelling.

When capacitor is swelled or damaged, we must check again problems as listed above.

Firstly, we must check connections, designs, capacitor’s quantity with specialized component: Support component for connection, VOM, ampere pliers, capacitor meter: Analizer for power quantity component.

• Due to connections: Circus snails.
• Due to MC, CB is damaged: replacing new components
• Due to capacitor is low quantity: Replacing better capacitors.
• Due to designs: installing fans, dustproof, moisture proof.
• Due to harmonics: Harmonics filter for capacitor by setting up for Reactor: Harmonics filter for component by setting up roll filter ( DC-DC circuit, AC Driver, DC Drive…), checking and replacing low quantity accessories; filtering all harmonics in upsteam for system.

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