Line Chokes are a simple and effective way to protect both the power supply against the negative impact of the inverter and inverter protection against interference from the mains, Line Chokes perfectively reduce the effects of transients limiting the amplitude and steepness of the current pulses. Also line chokes will considerably reduce the harmonics, which is generated by AC VFDs and DC drives.
Advantages
• Limitation of starting and short circuit currents
• Limitation of the steepness of di/dt current rise
• Reduction of harmonics generated by the power supply network
• Reduction of energy losses on the input side
• Limitation of switching voltage dips
• Protection and increased life cycle of the capacitor in the DC circuit
Technical Specifications
| Rated Voltage | 230V, 440V, 690V...1000V * |
| Rated Power | 0.5KW - 1000KW * |
| Rated Current | 5A - 3000A |
| Cooling | Air Cooled / Oil Cooled |
| Core | Iron Core |
| Operating Temperature | 50° C |
| Fundamental Frequecy | 50Hz |
| Thermal Protection | Yes |
| Impedance | 1.5%, 2%, 3% and High Impedance-5% * |
| Short Term Overload | 180% from the rated current |
*Customized design can also be supplied.
Impedance Options
FORETEC Line Reactors are designed to provide the best protection for both your drive and your application. As input impedance can significantly improve drive performance, please ask us for more technical details and proper sizing of reactors for your drives.
Advantageous are as follows
Reduction of nuisance tripping caused by
• Transient voltages caused by capacitor switching
• Line notching
• DC bus overvoltage tripping
• Inverter overcurrent and overvoltage
Additional benefits include
• Lowering injected percentage of harmonic current
• Improving true power factor
• Reducing cross-talk between drives
• Adding impedance to drives with DC link chokes/ reactors when more impedance is desired due to a relatively stiff source
Line chokes to protect from commutation
Another reason to avoid fixed, unfiltered capacitor banks is commutation. As the inverters of electronic loads switch on and off to draw current there is sometimes an overlap between the phases. When this happens, even for a very brief period, there is a direct short between the phases being switched.
Poorly designed hardware and misbehavior of SCR or IGBT either by improper trigger pulse or malfunction also behind the reason for these issue.
Above said these period is called commutation. It appears as a notch in the voltage waveform. This notch is a very quick drop in voltage and can cause damage to other loads. The best way to detect commutation is with the use of a power-recording meter or oscilloscope. Commutation is usually easy to eliminate, as the installation of an in-line reactor will prevent this from occurring. Other benefits from the reactor is reduction of the short-circuit current at drive and a decrease in the magnitude of voltage harmonics that the drive generates in the power system.
High impedance “Z” offers the same superior benefits as Low “Z” plus following additional benefits
• Helping prevent drive component damage
• Providing maximum harmonic mitigation without adding capacitance