CT / MRI
Imaging Equipment
15%
THD
- Image Artifacts — Misdiagnosis risk, requires repeat scans, doubling patient wait time
- Equipment Overheat — Transformer derating, shortened component lifespan, unplanned maintenance
Power Quality Solutions for Commercial & Medical Buildings
CHITEK retrofits AHF and SVG onto existing commercial and medical switchboards to cut harmonic distortion, neutral current and capacitor resonance. Typical sources are single-phase LED drivers, lifts and imaging equipment. In most cases the existing capacitor bank stays in service, with anti-resonance control and selective filtering orders holding the installation stable.
LED lighting, lifts, chillers and imaging equipment fill modern commercial and medical buildings. Single-phase LED drivers add third-harmonic current onto the neutral conductor, while capacitor banks installed for power factor correction can resonate with the transformer. CHITEK retrofits AHF onto existing switchboards without replacing the compensation equipment.
Reviewed by the CHITEK power quality engineering team · Last updated
AHF or SVG in a commercial building?
The split usually follows the dominant symptom: overheating neutrals and LED distortion point to AHF, while chiller reactive demand and lift surges point to SVG.
| Aspect | AHF (Active Harmonic Filter) | SVG (Static Var Generator) |
|---|---|---|
| What it does | Injects a compensating current that cancels the harmonic current drawn by non-linear loads. | Supplies or absorbs reactive power continuously to hold power factor and support voltage. |
| Primary target | Current distortion (THDi) and harmonic spectrum at the point of common coupling. | Power factor, voltage fluctuation and reactive demand across the load cycle. |
| Typical trigger | VFD banks, rectifiers, welding sets, induction furnaces, LED drivers, UPS rectifiers. | Low or swinging power factor, voltage sag and rise, weak or long feeders, EV load steps. |
| Behaviour at light load | Compensation scales with the measured harmonic current, so output falls as load falls. | Holds output as required to reach the target power factor even at near-zero active load. |
| Use in this sector | Neutral and harmonic correction on floors dominated by LED lighting and single-phase electronic loads. | Reactive support for chiller and HVAC banks where power factor correction is already penalised, or to replace a resonating capacitor bank. |
Where a capacitor bank is already installed, the survey must confirm whether it can stay in service. Anti-resonance control and CT placement decide this, not the device type alone.
Typical power quality problems
Medical Scenario
Hospital / Clinic / Rehabilitation
Operating Room
Surgical Equipment
ms-level
Voltage Sag
- Surgery Interruption — Momentary outage, equipment reboot cycle, procedure delays
- Life Safety Risk — Critical support equipment malfunction, emergency backup transfer latency
Laboratory
Sensitive Analyzers
High
Zero-seq. Current
- Phase Imbalance — Precision instrument drift, calibration invalidated, reagent waste
- Neutral Overload — Overheated conductors, fire risk, N-line burnout potential
Commercial Office Scenario
Office / Mall / Hotel
Lighting
LED Driver Harmonic
23%
THD
- Severe Flicker — Visual fatigue, reduced productivity, occupant discomfort complaints
- Neutral Overheat — Triplen harmonic accumulation, N-line burnout, fire hazard
Elevator
VFD Start-up Surge
7x
Inrush
- Voltage Dip — Equipment trip, control system reset, passenger entrapment risk
- Mechanical Wear — Frequent maintenance, brake pad replacement, rope fatigue
HVAC
Compressor Reactive
0.65
Power Factor
- Penalty Charge — Utility power factor surcharge, monthly bill 30%+ increase
- Transformer Overload — Excess reactive current, overheating, shortened service life
Lab & Cleanroom
Semiconductor / Biotech / Precision Mfg
Cleanroom
FFU Fan VFD
> 1.0
Pst Flicker
- Yield Loss — Wafer defect density increase, batch rejection, revenue impact
- Light Fluctuation — Photolithography misalignment, inspection false rejects
Lab Equipment
Sensitive Instruments
30%
Voltage Dip
- Data Loss — Unsaved measurement data, experiment interruption, reagent waste
- Calibration Drift — Post-sag recalibration required, 4-8 hrs instrument downtime
Cooling Pumps
Motor Start-up
5~8x
Inrush
- Bus Voltage Drop — Cascade trip risk, neighboring equipment brownout, batch shutdown
- Breaker Trip — False overcurrent trip, unplanned production halt, restart SOP
Commercial & Medical case studies
Each case below is written up the same way: what the site was, what the survey measured before anything was specified, what was installed, and what the acceptance test showed afterwards. Projects marked Typical Configuration are illustrative — sizing for those always starts from a site survey rather than from the table.
Commercial Building
LED Lighting Harmonic & Neutral Overload Retrofit — Wholesale Mall, Guangzhou
Current distortion 49% → 2.75%; neutral zero-sequence current 365.76 A → 25.19 A
Background
A wholesale garment market on a single 2,500 kVA transformer at roughly 90% load, with two compensation cabinets totalling 600 kvar. The dominant load is single-phase LED lighting and LED video walls on the trading floors.
What we measured
- Floor 1 phase current distortion 49% before the retrofit
- Neutral zero-sequence harmonic current 365.76 A
- Neutral apparent current 369 A, including unbalance current
- Busbar voltage distortion 4.75%
Equipment installed
-
AHF-200A × 2 units Active Harmonic Filter 3-phase 4-wire, main incoming switch on each trading floor
Project overview
2,500 kVA transformer at 90% load with 600 kvar of capacitor banks. LED lighting and LED video walls fill the mall — single-phase LED drivers inject heavy 3rd harmonic that adds up on the neutral conductor, taking current distortion to 49% and overloading the N line.
Before / After
Distortion 49% → 2.75% · Neutral current 369 A → 36.51 A
Key results
- Neutral zero-sequence harmonic 365.76 A → 25.19 A
- Neutral apparent current 369 A → 36.51 A (including unbalance current)
- Busbar voltage distortion 4.75% → 3.75%
- Accepted on test against GB/T 14549
Scope and limitations
Measured on the floor incoming feeders rather than at the utility metering point, so the figures describe the building distribution, not the site's PCC. Only two floors were treated.
Frequently asked questions
Why does the neutral conductor overheat in a building full of LED lighting?
Single-phase LED drivers draw a non-sinusoidal current that is rich in third harmonic. Third-harmonic currents do not cancel on the neutral, they add. On a heavily lit floor the neutral can end up carrying more current than a phase conductor.
Can we keep our existing capacitor bank?
Usually yes. The risk is parallel resonance between the capacitor bank and the transformer inductance, which amplifies harmonics instead of removing them. Anti-resonance control and selective filtering orders let the AHF operate with the bank still in service.
Does a hospital need a different approach from an office building?
The harmonic sources differ, and the consequences are different. Imaging equipment and surgical loads are sensitive to voltage sag and phase imbalance, so the survey has to cover sag depth and unbalance, not only current distortion. The filtering hardware is the same product family.
Will the retrofit require a shutdown?
The filter connects in parallel at the switchboard, so most retrofits are carried out on the existing board. The outage window is set by your site isolation and permitting procedure rather than by the equipment itself.
Related products
Solutions for other industries
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Every project on this page started with a measured survey. Send us your single-line diagram and load list and we will tell you what we would measure first.
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