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Capacitive Load Banks

ASCO load bank capacitors
What is Capacitive Load?

In alternating current systems, voltage and current rise and fall at the frequency of the power source. Whether voltage and current rise together depends on the characteristics of the load, for which there are three types. Resistive loads, such as heating elements and incandescent lighting, have the least effect, with voltage and current rising and falling together, a condition known as unity. Inductive loads, associated with energy used to spin motors and create magnetic fields, cause changes in voltage to lag changes in current. The ratio by which voltage leads or lags current is known as the Power Factor.

Capacitive loads are the third type, and are opposite of inductive loads. Capacitive loads include energy stored in materials and devices, such as capacitors, and cause changes in voltage to lag behind changes in current. Capacitive loads are less common than inductive and resistive loads, but are becoming more common with the deployment of increasingly complex electronics.

What is a Capacitive Load Bank?

Capacitive load banks produce the same effect as any other load bank. It applies load to a circuit and dissipates the resulting electrical energy to simulate a specific application. However, unlike other load banks, capacitive load banks use capacitors, which contain two conductive surfaces separated by an insulator to store potential energy in an electric field.

Capacitive load banks house industrial capacitors within an equipment enclosure, and are rated in Volt-Ampere/kilo Volt-Ampere (VArs/kVArs). Their controls allow operators to specify the exact amount of load required for a test. For most applications, capacitive load banks are used together with resistive load banks to adjust the power factor. ASCO’s market-leading Sigma controls allow fully customizable power factor selection to suit each application. The controls allow operator to work in percentages of load, and to select loads as small as 1 kVAr depending on the model.

Common Capacitive Load Bank Applications

Power Factor Correction

Capacitive load banks are often used to adjust power factors in industrial facilities, where capacitive load banks are added to circuits to counteract inductive loads from motors, compressors, and lighting. This moves power factors close to 1, a condition known as unity. The closer to unity, the more efficient and economical a facility will become.

Power System Research and Development

Capacitive load banks are often permanently installed at research and development facilities to evaluate how power systems adapt to fluctuations in capacitive load. Specific load profiles are applied for prescribed time periods. If a system satisfactorily adapts to changes in capacitive load, testing can progress to the next stage. Capacitive load banks are especially common in marine gen-set testing because inductive devices such as inverters and battery packs are increasingly used in marine applications.

For more information about capacitive load banks please read the white paper

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