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Fast Response, Transient Free, Real Time Hybrid Harmonic Filter

• Fast Response
• Transient Free
• Non-resonant
• Reduction of System Losses
• Reduction of Harmonics
• Reduction of Flickers
• Reduction of Voltage Drop

Advantages

• Transient Free capacitor group switching, using electronic switching elements
• Prevents damage to sensitive electronic equipment
• Saves energy
• Harmonics filtration
• Accurate power factor control, even in the presence of harmonics
• Dramatically increases the life expectancy of switching elements and capacitors
• Considerably lower temperature rise of the capacitors and inductors due to unique scan feature
• Built-in three phase network analyzer, measuring all network parameters including harmonics
• Unique self testing and comprehensive reporting feature
• Cycle by cycle reactive power compensation (total acquisition time of 5-20mSec)
• Prevents voltage drop and flickering
• Used for Real Time applications, such as spot welding and motor start-up
• Enhances capacity of local generator systems, such as diesel and windmill generators

Introduction

The HYBRID HARMONIC FILTER is state of the art, electronic switching device designed to replace electromechanically switched equipment in power factor correction (PFC) and harmonic filtration systems.

Connection and disconnection of the capacitors to and from the network occurs at zero current crossing. This smooth connection avoids the transient effects typically created by electromechanically switched PFC systems. The total acquisition time (full compensation of reactive current) is only 5 to 20ms which is much faster than electromechanically switched PFC systems.

The eletronic switches do not wear out or deteriorate during the switching process and the capacitors are not adversely affected by transients. These advantages contribute to a much longer life expectancy compare with electromechanically switched PFC systems. The power factor is controlled very accurately by means of an advanced closed loop control & measuring unit, that takes into consideration all three phases and the effect of harmonics (1 through 63).

The switching element can perform an unlimited number of switching operations. The connection of one group of the LC (Inductor and Capacitor - Compensation Group) occurs simultaneously with the disconnection of another group. This operation is performed every few seconds and engages all LC Groups in turn, resulting in a reduction of mean current due to the lower ratio of engagement time to cycle tune (duty cycle).

The scan feature, together with the unique reactor design, substantially reduces the temperature rise of the reactors and protects the cabinet from overheating.

There is an ongoing cumulative reduction of capacity in electromechanically switched PFC systems due to the effect of transients during connection and disconnection. This can be detrimental to detuned Electromechanically switched systems where the changes in ratio between the capacitors/reactors shift the resonance frequency, which may result resonance. The HYBRID HARMONIC FILTER prevents these conditions.

The controller is a full measuring device, with an LCD display, which measures cycle by cycle all network and internal parameters. The Hybrid Filter is a fast response system that is designed to compensate any variation in reactive power within one cycle of the network.

Correction compensation using the Hybrid Filter The top graph demonstrates how the Hybrid Filter compensates the reactive current of fast load with a duration of 14 cycles. Typical acquisition time (full compensation of reactive current) is less than one cycle and the total current is substantially reduced. Adverse effects of slower response systems The bottom graph demonstrates incorrect compensation where the response time is 3 cycles for the connection of a single group and the acquisition time required to connect a total of 4 groups is 12 cycles. Due to the delay in compensation the current is partially reduced and due to the corresponding delay in disconnection of the capacitor groups is residual current. The total effect of the compensation systems on the current is negative since the average current of the load is increased instead of being reduced. This increases voltage flickering due to over compensation.

Power IQ Measurement & Analysis Software

This software display the system's status as well as the measurement results on numerous screens running under Windows. All network parameters, including harmonics up to the 63rd can be recorded at preselected intervals. The duration of the recording is only limited to the size of the computer's hard disk. The software can be set to record data based on the selected triggers of the various network parameters, such as voltage sags and/or current spikes. The system records before and after the trigger event. The software has intranet and internet support.

The Hybrid Filter include custom designed, iron core reactors in series with the capacitors.

Iron Core Reactors The iron core reactors are manufactured under tight tolerances. The reactors are constructed with a laminated low hysteresis loses iron core, precision controlled air gaps and copper windings, and have class H insulations (180°C) . The detuned reactors prevent resonance by shifting the capacitor/network resonance frequency below the first dominant harmonic (usually the 5th) Capacitors The capacitors are low loss (0.25W/kVAr) in cylindrical aluminium casing. The capacitor is a metallized polypropylene film capacitor with self healing properties and an overpressure tear off use. Switching Module The switching module consists of solid state switching elements, which provide reliable, high speed, transient free operation. Each switching module switches up to three capacitor groups, using double phase electronic switches for each three phase LC (Inductor-Capacitor) group.

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