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Power Capacitors
1 Series · 17 Models
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Power Capacitors Overview
Self-healing power capacitors provide power factor correction by offsetting the reactive power drawn by motors, transformers, and other inductive loads. QDTB units use metallized film technology rated 0.40-1.0 kV from 1 kVar to 50 kVar at 50/60 Hz. The BSMJ series (PP film, oil-immersed) and BCMJ series self-heal on dielectric breakdown, improving safety and service life while reducing losses, improving efficiency, and avoiding utility power factor penalties.
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Application Scenarios
Power Factor Correction
Compensates reactive power to avoid utility penalties and improve efficiency.
Industrial Plants
Local compensation for motors, transformers and welding equipment.
Commercial Buildings
Keeps power factor within utility requirements for large facilities.
Distribution Substations
Bulk reactive compensation on LV distribution networks.
Motor Compensation
Individual or group correction to reduce line current and losses.
Renewable Energy
Reactive support for solar and wind installations.
Technical Advantages
Self-Healing
Metalized film technology self-repairs dielectric breakdown for safety and longevity.
Low Loss
Low dielectric losses keep running costs down.
Built-In Safety
Internal discharge resistors and over-pressure protection.
Long Service Life
Robust construction rated for years of continuous operation.
FAQ - Power Capacitors
What is power factor correction?
How do I choose the kvar rating?
Are power capacitors safe?
What is the minimum order quantity (MOQ) for Power Capacitors?
What is the delivery time for Power Capacitors?
Which standards and certifications do your Power Capacitors comply with?
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Oil-Immersed vs Self-Healing vs Detuned Bank: How to Choose
| Oil-Immersed PP Film (BSMJ) | Self-Healing Film (BCMJ) | Bank with Detuning Reactor | |
|---|---|---|---|
| Construction | Metallized polypropylene film in an oil-filled can | Metallized film in a dry or gas-filled case | Standard capacitor units in series with a reactor |
| Failure behaviour | Internal fuse and overpressure disconnector clear a failed element | Film self-heals at the breakdown point and keeps working | Film self-heals, and the reactor keeps harmonics out |
| Harmonic tolerance | Limited — a harmonic-rich bus heats the dielectric | Slightly better, but still a plain capacitor | Designed for the harmonic load, with the bank detuned |
| Installation | Rack or cabinet mounting with ventilation | Compact units for panel or cubicle mounting | Needs panel space for both capacitor and reactor |
| Service life | Long, provided the ambient and voltage stay in range | Long, with self-healing covering minor breakdowns | Longest where harmonics would otherwise age the bank |
| Cost | Baseline | Similar to oil-immersed at the same rating | Highest, because the reactor is added |
| Typical application | Distribution substations and motor compensation | Commercial buildings and small plants | Plants with drives and rectifiers on the same bus |
Where QDTB® Power Capacitors Are Specified
Power capacitors are specified wherever motors, transformers and other inductive loads have left the power factor below the level the utility charges for: industrial plants, commercial buildings and distribution substations. The bank offsets the reactive demand locally, which frees feeder and transformer capacity and removes the penalty from the bill.
Motor compensation uses smaller units close to the load, while a central bank at the main board handles the plant total. The kvar rating is set from the measured power factor and reactive demand rather than from a rule of thumb, because an oversized bank over-compensates and an undersized one still pays the penalty.
Where drives, rectifiers or welding equipment share the bus, the capacitors go in behind a detuning reactor, otherwise the harmonic current overheats the dielectric and the bank fails early. Self-healing film construction covers the minor breakdowns that would otherwise end a plain capacitor's life.
Units are rated 0.40-1.0 kV from 1 kVar to 50 kVar at 50/60 Hz and built to GB/T 12747.1. Internal discharge resistors bring the terminals down to a safe voltage once the bank has been isolated.
Frequently Asked Questions
What is power factor correction?
It adds capacitance to offset inductive reactive power from motors and transformers, reducing line current, losses and utility penalties.
How do I choose the kvar rating?
Measure the load's power factor and reactive demand, then select capacitors to bring power factor to the target (typically 0.95).
Are power capacitors safe?
Yes. Self-healing metalized film and internal discharge resistors prevent dangerous failures, unlike older oil-filled types.
What is the minimum order quantity (MOQ) for Power Capacitors?
One unit for standard products. Custom-designed equipment is quoted on specifications — send your parameters or drawings and our sales team will confirm the MOQ for your configuration.
What is the delivery time for Power Capacitors?
Standard units are delivered in 30-45 days. Custom or large-capacity units follow a project-specific schedule confirmed at quotation. Rush orders can be accommodated for urgent projects.
Which standards and certifications do your Power Capacitors comply with?
They are designed and tested to GB/T 12747.1. All QDTB® equipment is ISO 9001 certified and CE marked, and the company operates ISO 9001, ISO 14001 and ISO 45001 management systems.