The Most Trusted Name in Power Factor Correction and Harmonic Filtering


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NEPSI's actiVARTM, Medium Voltage Metal-Enclosed Thyristor Switched Harmonic Filter Banks are custom designed for power systems requiring instantaneous var support to mitigate voltage sags, voltage flicker, and high inrush currents associated with starting and impact loading of large motors and dynamic loads. This equipment stabilizes your system voltage, helps your equipment run more smoothly, and increases your systems efficiency and throughput.

Hybrid designs are available that include NEPSI’s well known and reliable mechanically switch harmonic filters to economically increase the benefits of this product to include power factor correction and harmonic distortion attenuation.

Thyristor valves used in the actiVARTM provide “fast vars” for voltage sag and flicker mitigation while standard capacitor switches provide “slow vars” for harmonic distortion attenuation and power factor correction.

The actiVARTM samples your phase voltage, load, and line currents at rates exceeding 7,000 times a second, analyzing them in real-time, and instantaneously responds to abnormalities in real-time. Changing state 60 times a second, the actiVARTM effectively stiffens your voltage supply. Industries using high dynamic loads such as welders, shredders, rolling mills, and arc furnaces benefit from this product and have seen paybacks in less than 1 year with improved plant productivity and power factor improvement.

The actiVARTM is available in voltages from 2.4kV through 24.9kV, with MVAR ratings from 0.5 MVAR to 100 MVAR. The actiVARTM is designed for placement in outdoor or indoor substations and come fully assembled, tested, and ready for interconnection.



With single-cycle response times, the actiVARTM mitigates voltage sag and voltage flicker, allowing large dynamic loads to operate efficiently while greatly reducing their impact on the power grid. The actiVARTM can dramatically lower both customer and utility investments - while providing customers improved performance levels.

The following table summarzies the many features and benefits of applying the actiVARTM to your system.




Provides near instantaneous mitigation of voltage sags and voltage flicker, resulting in a near perfect voltage profile.

The near perfect voltage profile allows for more efficient operation of your equipment; - allowing for higher production levels and throughput.

Valve Design

Transient Free Operation, eliminating adverse effects of switching transients.

Power Factor Correction
& Harmonic Filtering

Corrects plant power factor, reducing KVA and power factor penalties, increasing system capacity, while improving your voltage profile.

Reduces plant voltage and current distortion. Designed for compliance with IEEE 519 harmonic distortion limits.

Metal-Enclosed Design

All-Inclusive Design - Equipped with integral disconnecting device, protection, and control.

Comes fully assembled, calibrated, tested, and ready for interconnection.

Enclosure protects key components from wildlife and atmospheric contaminants.

Small footprint

Easy to maintain

Designed and built by an ISO 9001:2008 certified company with a proven track record of quality and performance.

Safety - Enclosure prevents inadvertent contact.

Key Interlock System

Safety and proper sequence of operation


Easy to purchase.

Fully integrated design


NEPSI's actiVARTM is rated and configured to meet customer requirements for voltage, basic insulation level (BIL), available short circuit current, reactive power rating, and frequency. Internal components such as disconnect and grounding switches, circuit breakers, capacitors, capacitor switches, thyristor valves, and capacitor fuses are chosen based on their ratings, costs, availability, and NEPSI's experience with the supplier's quality, service, and reliability.



Bank Configuration:Thyristor Switched: Single Step/Multiple Step
Hybrid Design: Thyristor & static switched
Filter Types: Notch (Band-Pass), High-Pass, C-High-Pass, Multi-Tuned
Operating Voltage (line-to-line): 2.4kV – 24.9kV
Operating Frequency: 50 Hertz | 60 Hertz
Reactive power output: 0.5MVAR – 100 MVAR
(500kvar – 100,000 kvar)
Tune frequency (Hz) 85 Hz 2100 Hz
(1.4th Harmonic – 35th harmonic)
High-Pass (damping) resistor rating: 1 ohm to 1000 ohms
10kW/Phase - 200kW/Phase
Short circuit
(asymmetrical momentary):
16kA - 61kA
Impulse withstand voltage
(Basic Insulation Level):
60kV – 125 KV
Short-time withstand voltage
(1 minute 50/60 Hertz):
19kV – 60kV
Control voltages: AC Volts: 110, 115,120, 220, 50/60hz
DC Volts: 24, 48, 110, 125, 220
Operating temperature range: -50°C to +55°C
-58°F to 131°F
Maximum altitude without de-rating: 1,000 Meters
3,300 Feet
Enclosure: (NEMA): 1, 3R, 4X, 12
(IEC): IP10, IP14, IP56, IP52
Arc Flash Mitigation: Passive & Active
Hazardous Locations: NEC Class 1 & 2, Div. II
Seismic: As specified - Zone 4
Capacitor fusing: Internally fused | Externally fused
Performance Standards: SEMI (Semiconductor Equipment and Materials International), F47-0706, F49-0200, and F50-0200s

CBEMA (Computer and Business Electronic Manufacturers Association), curve referenced in ANSI/IEEE Std. 446-1987

ITIC (Information Technology Industries Council) tolerance curve

IEEE Standard 1346-1998, Recommended Practice for Evaluating Electric Power Systems Compatibility with Electronic Process Equipment

IEEE 1250-1995, Guide for Service to Equipment Sensitive to Momentary Voltage Disturbances.

IEC 61000-4-11 and 61000-4-34, (International Electrotechnical Commission)

IEEE Std. 1453, Table A.1, Recommended Practice for Measurement and Limits of Voltage Flucations and Associated Light Flicker on AC Power Systems

IEEE 519, Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems


NEPSI's actiVARTM is custom designed, configured, and rated to mitigate voltage sags, flicker, harmonic distortion, and power factor. Depending upon the performance objectives of the equipment, the actiVARTM may come with one or more conventionally switched filter stages. Conventionally switched stages that use standard capacitor switches are less costly, provide "slow vars" for power factor correction and harmonic distortion. Thyristor switched stages, the key component of the actiVARTM, provide "fast vars" to mitigate voltage sags and voltage flicker.

The physical arrangement of the actiVARTM, including component layout, incoming compartment configuration, filter type, and tuning point are customized to meet site specific constraints and requirements.

Click each of the headings below to learn more about our actiVARTM configurations.




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