Capacitor banks - give your appliances the rewards they deserve

In our daily life, you will use various electronic devices to save time. In order to work effectively, they need sufficient electricity. However, exceeding the requirements can cause insulation damage to the wires and machine short circuits. So, what can you do to balance voltage fluctuations? Place a capacitor bank so that they can obtain sufficient required power.What is a capacitor bank?

A capacitor bank is a set of capacitors within the same range, connected in series or parallel to store more electrical energy. A capacitor can store a small amount of charge, and a device can embed a capacitor. Substations use them to provide consumers with ufficient energy without power lag or current phase shift. Now, this technology has spread to home use to support your device.

How does it work?

Manufacturers design capacitor banks to correct AC fault currents or provide DC power. A capacitor has two conductive plates separated by the dielectric of a capacitor (such as air or any other material). Electricity causes these two boards to charge in opposite directions, so that a static electric field can be maintained between them.

Over time, charges begin to move from one plate to another, dissipating energy and providing electricity to connected devices. These small capacitor units are connected in parallel or series, increasing their capacitance and allowing them to distribute energy to power plants and large factories.

Type of capacitor bank

1.External fuse type：in this arrangement, each capacitor unit has its own fuse unit connected externally. Once any problems occur, the fuse will be blown out and the faulty capacitor unit will be disconnected. The bank continues to work without any interruption, but the voltage provided is lower than before. Furthermore, even if all units are healthy, the failure of the fuse unit can affect the performance of the capacitor bank.

2.Internal fuse typ：the internal fuse type connects each component of the capacitor to the fuse, all enclosed in the same box. You can easily install and maintain it because it has low-level units. When any single component fails, the group of capacitors can continue to operate. The main drawback is that if more components stop working, you cannot change each of them; On the contrary, you must purchase a brand new group.

3.Reduce Fuze:in order to eliminate the need for fused capacitor banks, a "low fuse" connects all capacitor units in series to form a series. Then, it connects each series in parallel to form a bank. When one capacitor fails, other capacitors in series will mask its missing capacity. Therefore, this type of capacitor does not require a fuse to operate.

What is the purpose of capacitor banks?

1.Compensating reactive power

Adding an inductive load to the system will reduce the quality of electricity provided by the main power supply. To improve the lag of power factor, you can add capacitors. Therefore, they can reduce the actual power load and overcome the deficiency of reactive power.

2.Power factor correction

During the distribution process, capacitors improve the stage of power transfer. It appears as an additional load in the system and reduces the waste of unused electricity. Due to the power factor being the ratio of the power used to the total power provided, capacitors are added to make these two quantities equal, thereby achieving a pf of 1.

3.Energy storage

Capacitor banks store energy in the form of charges, and without them, the system may be wasted. The larger the capacitance of a capacitor bank, the greater the energy it can store. Electrical equipment that requires DC power also uses capacitors to maintain power while charging their batteries.

4.Noise bypass

When capacitors are placed on a circuit, they serve as a source of high resistance, rather than being used for high-frequency signals. Therefore, you can use parallel capacitor banks to block noise. Therefore, signals with higher carrier frequencies will not be transmitted to electrical appliances, nor will sudden fault currents occur.

Reduce the cost of fault current

Due to the low power factor of the system, the friction inside the wires will waste a large amount of energy in the form of heat and reaction forces. However, power suppliers are not concerned about this issue, as you receive less than the bills you pay. Installing a capacitor bank can reduce this issue and save additional energy to meet the requirements of your device.

Substation capacitor bank

Due to the fact that capacitor banks can improve power factor and provide voltage quality, they are installed in substations. They connected several capacitors in series to improve the voltage curve. Through its addition, the power factor angle is reduced because the current is now leading the voltage. As the angle decreases, you know that the power factor is improving.

By increasing the inductive load on the user side, the demand for reactive power increases. A load, such as a water pump, requires more reactive power to generate magnetic flux and move its coils. The increase in demand leads to a decrease in power factor, resulting in imbalanced power consumption. More energy loss becomes a burden on the factory. When you use capacitor banks in production, they become a source of reactive power for consumers, making the factory's work more efficient.

Can we only use capacitor banks on a larger scale?

Over time, the usage range of capacitor banks has also expanded to a smaller range. Mobile phones use low-power capacitor banks and supercapacitors to reduce their charging time. Supercapacitors can hold up to a hundred times more charge than ordinary capacitors, and we also use them as low-voltage rechargeable batteries in most cases.

In wireless space, tiny microelectromechanical systems, also known as MEMS, replace full-size capacitors. Research has shown that capacitors can also provide the large pulse current required by many pulse power devices and weapons. A high-energy bank equipped with modern semiconductor switches can create pulses of up to hundreds of kilojoules and high ampere electrical pulses. Radar, nuclear fusion research, and Marx generators are common and unique applications of this high-density pulse.

How to protect capacitor banks?

During the installation process, in order to limit surge currents, reactors are connected in series on capacitor banks. These reactors can protect it:

1.Overcurrent (unbalanced) relay

Due to a blown fuse or internal short circuit in the capacitor bank, some capacitor units may malfunction. These units are no longer connected, causing a burden on other units within the chain. At first, this may not be a problem, but as the number of faulty units increases, the asymmetry becomes more pronounced. An overcurrent relay can detect this imbalance within the capacitor bank, so you can replace it in a timely manner without causing any damage to the entire circuit.

2.Overload relay

Capacitors are connected in series with reactors, so it is not easy to detect overvoltage if it occurs. Due to its ability to withstand only 110% of the rated voltage, after this increase, the capability curve begins to follow an inverse time characteristic, meaning that the current begins to decrease.

To detect this, an overload relay was introduced that measures the current from the battery pack and converts it into the corresponding voltage. It can prevent capacitors from releasing energy in the event of insufficient voltage supply, even if it is not necessary.

3.Short circuit protection

In addition to overcurrent and voltage issues, capacitors are also susceptible to short circuits and ground faults. For this situation, 2-phase or 3-phase short-circuit protection and ground overcurrent relays can be a good solution.

What should be considered when selecting a capacitor bank?

When selecting a capacitor bank in any situation, you must consider the following parameters:

1.Voltage level to maintain peak voltage and surge voltage. It has a normal peak voltage of up to 110% and a normal effective voltage of 120%.

2.KVaR level to ensure the system obtains sufficient reactive power. The calculation of capacitor banks requires initial and expected power factors.

3.Temperature level to maintain the temperature of the capacitor bank during operation. To calculate this rating, you must observe the temperature rise and other energy losses under sunlight.

4.Insulation level, as the medium used will play a significant role in determining the energy provided, just like in any other electrical equipment.

5.The rated current level, or the effective value of the normal current for charging capacitors.

6.Discharge time, see how long the capacitor will deplete its energy.

7.Single phase or three-phase, as both are useful for specific reasons.

Conclusion: 

Electricity is transmitted from the main power source to your home through wires. During this process, the frictional force inside the wire converts this energy into thermal energy and other forms of energy.

If you install a capacitor, the energy that heats the wires and strains your device will be directed towards it. Therefore, it reduces your bill and saves you the need to repair motors affected by power failures.