CKSG Series Low-Voltage Series Reactor

Application
This series of dry-type iron-core series Reactors is used in low-voltage Reactive Power Compensation cabinets and is connected in series with Capacitors. When there are a large number of harmonic sources in the low-voltage grid, such as rectifiers and converters, the resulting higher-order harmonics can seriously threaten the safe operation of main transformers and other electrical equipment. When the reactor is connected in series with the capacitor, it can effectively absorb grid harmonics, improve the system voltage waveform, enhance the system power factor, suppress inrush currents and operational overvoltages, and effectively protect the safe operation of the capacitor.

Operating Environment

• Altitude: not exceeding 2000 meters;

• Ambient temperature: -25 to +45°C, relative humidity not exceeding 90%;

• Free from harmful gases, flammable, or explosive materials;

• The surrounding environment should have good ventilation. If the series reactor is installed inside a cabinet, additional ventilation equipment should be provided.

Technical Parameters

• Applicable for 400V and 660V systems;

• Reactor types: 6%, 7%, 14%, etc.;

• Rated insulation level: 3kV/1min;

• Temperature rise limits: core ≤ 85K, winding ≤ 95K;

• Noise level: ≤ 45dB;

• Continuous operation at 1.1 to 1.35 times rated current;

• Reactance linearity: the ratio of reactance at 1.8 times rated voltage to reactance at rated current should be ≥ 0.95;

• Phase-to-phase reactance deviation: ≤ ±3%;

• Temperature class: H (≥ 180°C).

Selection and Considerations for Low-Voltage Series Reactors
The capacitor is the main component of a reactive power compensation system. Incorrect parameter selection will directly affect the service life and performance of the entire system. Therefore, parameters should be selected carefully. The rated voltage of the capacitor should generally be higher than the maximum operating voltage and account for voltage fluctuations, as well as the voltage rise across the capacitor after connecting the series reactor. Consider the bus voltage rise after capacitor energization, the harmonic voltage, and the harmonic voltage across the capacitor to ensure long-term safe and reliable operation.

General Guidelines for Series Reactor Selection

• If the reactor is used only to limit inrush current, it can be selected as 1% of the capacity;

• When grid harmonics are dominated by the 3rd harmonic or higher and the 3rd harmonic content is high (exceeding or close to the limit), a 12%-13% series reactor can be selected;

• When grid harmonics are dominated by the 2nd and 5th harmonics and the 3rd harmonic content is low while the 5th harmonic is high, a 4.5%, 6%, or 7% series reactor should be chosen. A 1% series reactor should not be used.

Recommendations for Installing Series Reactors

• For operating capacitor systems, the selection of series reactors must be cautious. They cannot be arbitrarily combined with capacitors and must consider the harmonic conditions at the connection point;

• For newly built substations, the suitability of series reactors must be further verified based on calculations and actual measurements. The harmonic situation of the grid should be understood, and the capacity of the capacitor bank should not be arbitrarily increased or decreased for reactors that are appropriately matched.