202628 | Toshiba 125HP 125A 600V 3% Impedance Line Reactor in Type 1 Enclosure

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Toshiba line reactors, also known as chokes, are passive-power conditioning devices. They are often applied to correct or prevent power-line problems inherent in Variable Frequency Drive applications. Available in Open, Type 1, and Type 3R enclosures, when applied to the input of a VFD, the line reactor protects the drive from power line issues or vice versa.

Line Reactors are often applied to a VFD’s input to reduce reflected harmonics to the power line or where high ratios exist between Point of Common Coupling (PCC) and a VFD’s power capacity. Toshiba recommends using a line reactor where the ratio is greater than 20:1, for example, when a transformer has a capacity of 1000kVA and the connected VFD has a capacity of 11kVA (10 HP) for a ratio of 90:1 (stiff line). Additionally, nuisance trips due to line voltage spikes can be minimized as the line reactor will reduce the magnitude duration of the transients.

Line reactors may also be added to a VFD’s output in order to add inductance to a low impedance motor. They should not be used to address excessively long motor lead-lengths, however, as lead-length issues should be corrected using Long Lead Filters.

There are two factors to consider when selecting the amperage and percent impedance for an application. First, the reactor must meet or exceed the maximum steady-state input current of the application. Second, consider the voltage drop across the reactor at full load as a voltage drop will occur equal to the impedance of the reactor.

A 3% impedance reactor is typical for the line side of a drive and will prevent nuisance tripping of drives in most applications. Additionally, if line voltage is low a 3% impedance line reactor is recommended to minimize the occurrence of a low voltage situation. A 5% reactor should be selected if harmonic content is severe or if the goal is to meet IEEE519 recommendations. Finally, a 5% impedance line reactor is typically used for the load side of a drive.