Power Quality Solutions by Industry
Harmonic filtering and reactive compensation for six application sectors. Each page names the equipment that causes the problem — VFD banks, welding sets, induction furnaces, UPS rectifiers, LED drivers, traction loads, inverter clusters — and the device CHITEK installs for it.
Choose your industry
Industrial
Harmonic filtering and reactive compensation for welding shops, induction furnaces, CNC and servo lines, VFD banks, compressor and pump feeders, plating rectifiers and rolling mill drives.
View solutions →
Commercial & Medical
Retrofit AHF and SVG onto existing switchboards in shopping malls, hospitals and clinics, laboratories, LED-lit offices, hotels and transport terminals.
View solutions →
Data Center
UPS input harmonics, phase imbalance and reactive support for colocation halls, enterprise data centres, financial and banking sites, edge and remote nodes and disaster recovery sites.
View solutions →
Renewable Energy
Harmonic interleaving, flicker and reactive swing at utility-scale PV plants, wind farms, battery energy storage (BESS), hybrid PV plus storage, CCHP plants and microgrids.
View solutions →
Rail Transit
Power factor and harmonic control for DC fast-charging hubs, fleet and bus depots, public charging stations, workplace chargers and rail traction.
View solutions →
Power Grid
Reactive and harmonic control on transmission and distribution substations, urban distribution networks, long rural feeders, distributed generation tie-points and EV charging clusters.
View solutions →
What every project starts with
1. Measure first
A power quality survey at the point of common coupling: harmonic spectrum, reactive profile and load cycle. Sizing from transformer kVA alone is the usual reason an installation ends up undersized.
2. Size to the spectrum
AHF capacity follows the measured harmonic current; SVG capacity follows the reactive swing. Where a capacitor bank is already installed, anti-resonance control and CT placement decide whether it can stay.
3. Verify on site
Acceptance is measured after energisation against the applicable limit, normally GB/T 14549 or IEEE 519 at the point of common coupling.
Which device fixes which problem?
Two product families, and the split between them is not a preference — it follows from what the measurement shows. AHF removes harmonic current. SVG supplies and absorbs reactive power. The table below starts from the symptom, gives the reading that confirms it, and names the device that addresses it. Where a site shows both, the two are rated separately rather than sized as alternatives.
| Symptom | What to measure first | Device | Why it works |
|---|---|---|---|
| Neutral conductor running hot, or its current is close to a phase current | Neutral current vs phase current, and the 3rd / 9th harmonic content on the neutral | AHF | Triplen harmonics from single-phase electronic loads add on the neutral instead of cancelling. AHF is the only one of the two that removes them. Check phase balance first — unbalance alone can load the neutral without any harmonic contribution. |
| Power factor correction capacitors failing or switchgear tripping without an obvious fault | Whether the capacitor bank and transformer inductance put a parallel resonance near a harmonic order present on site | AHF | The bank is amplifying harmonics rather than filtering them. Selective filtering orders plus anti-resonance control let the bank stay in service. Where the filter CTs sample decides whether LC resonance can be excited. Sampling on the load side is the fallback. |
| Utility power factor penalty, or reactive energy appearing on the bill | Power factor and reactive demand across the whole load cycle, including standby and overnight | SVG | SVG holds a target power factor continuously, including when active load is near zero, which is where a capacitor bank loses control. If the site has a capacitor bank that steps in lumps, SVG also removes the over-compensation that shows up at light load. |
| Power factor measured leading at night or at the weekend | Power factor at minimum load, and the capacitance of any long underground cable runs | SVG | Cable capacitance generates reactive power at light load. SVG absorbs the excess instead of adding more. A conventional capacitor bank can only ever add reactive power, so it cannot correct this. |
| Equipment tripping or restarting on short voltage dips | Sag depth and duration at the equipment terminals, logged during the incidents | SVG | SVG responds within a cycle to hold bus voltage. It reduces the depth and duration of the dip; it does not replace a UPS for a sustained outage. Where the sag is caused by a large motor start on the same bus, reactive support at the bus is usually more effective than a larger source transformer. |
| Lights visibly flickering when a furnace, welder or large drive cycles | Pst / Plt short-term flicker severity at the point of common coupling | SVG | Flicker comes from a rapidly swinging reactive demand. SVG tracks the swing and cancels it; AHF does not address reactive swing. Flicker caused by a single intermittent arc load may need the load itself reviewed before reactive compensation is sized. |
| Harmonic distortion at the incoming supply above the agreed or statutory limit | Current and voltage harmonic spectrum, and which orders carry the most current | AHF | AHF injects a cancelling current, order by order, sized to the measured spectrum rather than to the load rating. Sizing from transformer kVA alone is the usual reason an installation ends up undersized. Measure first. |
| Transformer running hotter than its loading suggests, or being derated | Harmonic loss contribution and the K-factor or derating requirement for the load mix | AHF | Harmonic current causes extra eddy and stray loss that a standard kVA rating does not account for. Removing the harmonic current removes that loss. Derating is a symptom, not the problem. Confirm the harmonic contribution before assuming the transformer is undersized. |
| Harmonic distortion appearing after a VFD retrofit or a new drive line | Harmonic spectrum on the feeder that supplies the drives, at their operating duty point | AHF | Six-pulse rectifiers in drives are a characteristic harmonic source. The distortion scales with drive loading, so AHF output falls with load naturally. Multiple drives on one bus interleave their harmonics; the combined emission is not the sum of the individual ratings. |
| Inverter or PCS units tripping together on a PV, wind or storage site | Wideband oscillation and the resonance point formed by the inverter filters and the collector or grid impedance | AHF + SVG | Multi-inverter sites produce both interleaved switching harmonics and a reactive swing as output changes. The two are rated separately. The resonance scan belongs to a system study, not to an equipment selection. Ratings follow the study. |
| Voltage dipping each time a large load or a group of chargers starts together | Step size and repetition rate against the flicker and voltage-change limits that apply to the site | AHF + SVG | The step itself is largely a reactive event, so SVG carries most of it. Where the chargers or rectifiers also add harmonics, AHF is added on the same bus. Demand-charge exposure from the same load step is a tariff question and is separate from the power quality fix. |
| One phase carrying noticeably more current than the others, or motors running hot | Negative-sequence and zero-sequence current, and how the single-phase load is distributed between phases | AHF + SVG | The distribution problem has to be fixed first. AHF removes the harmonic component that rides on top of it; SVG supports the voltage where the imbalance produces a sustained unbalance. Re-balancing the single-phase load should always be considered before buying equipment. |
Which device do I need?
Walk the three questions below. The whole tree is on the page, so you can read the path end to end without clicking anything — or step through it if you prefer.
Step
What does the measurement show first?
Step
Is there an existing capacitor bank on the same bus?
Step
What is the power factor at minimum load, overnight or at the weekend?
Step
What conditions is the sag tied to?
Show the full decision path as a list
- What does the measurement show first?
- · Current distortion is above the limit → Is there an existing capacitor bank on the same bus?
- · Power factor is low, or reactive is being charged for → What is the power factor at minimum load, overnight or at the weekend?
- · Voltage dips or flickers under load steps → What conditions is the sag tied to?
- · Neutral current is high, or capacitors keep failing → Start with an active harmonic filter (AHF)
- Is there an existing capacitor bank on the same bus?
- · Yes, and it stays in service → Start with an AHF, with anti-resonance control
- · Yes, but it can be replaced or removed → Start with an active harmonic filter (AHF)
- · No capacitor bank on site → Start with an active harmonic filter (AHF)
- What is the power factor at minimum load, overnight or at the weekend?
- · Still low or lagging → Start with a static var generator (SVG)
- · Swinging, or measured leading → Start with a static var generator (SVG)
- · Fine at light load, only low at peak → Start with a static var generator (SVG)
- What conditions is the sag tied to?
- · A large motor or drive starting on the same bus → Start with a static var generator (SVG)
- · Several chargers or rectifiers starting together → Plan for AHF and SVG together
- · An external supply event, not a site load → Reactive support will help, but treat it as one part of the fix
Get a power quality assessment for your site
Send us your single-line diagram and load list and we will tell you what we would measure first.
Contact our engineers