Maximize Efficiency & Power Factor
A current transformer (CT) is an instrument transformer used to reduce high primary currents to a standardized low secondary current (typically 5 A or 1 A) for measurement, protection, and control purposes. Unlike ordinary power transformers, a current transformer operates with a primary winding connected in series with the load and a secondary winding that supplies measuring instruments, energy meters, or relays. Current transformers provide electrical isolation between high‑voltage circuits and low‑voltage instruments, ensuring operator safety. They are essential components in power factor correction systems, panel meters, and protective relaying schemes.
| Function | Typical Data / Description |
|---|---|
| Primary current measurement | 100 A – 5000 A (standard ranges) |
| Secondary output | 5 A or 1 A (industry standard) |
| Burden (VA rating) | 2.5 VA – 30 VA (depending on class) |
| Accuracy class | 0.2, 0.5, 1.0 for metering; 5P10, 10P10 for protection |
| Frequency range | 50 / 60 Hz |
| Insulation level | 0.72 kV / 3 kV / 6 kV / 11 kV typical |
| Overcurrent withstand | 1.2× rated current continuous, 60× for 1 second |
| Operating temperature | -25 °C to +55 °C |
This table helps engineers and procurement teams quickly match the Current Transformer to their system requirements.
| Parameter | Common Values / Range |
|---|---|
| Type | Wound primary / Bar primary / Split‑core / Window |
| Rated primary current (Ipn) | 100, 200, 300, 400, 500, 600, 800, 1000, 1500, 2000, 3000, 5000 A |
| Rated secondary current (Isn) | 5 A (most common) or 1 A |
| Rated burden | 5 VA, 10 VA, 15 VA, 30 VA |
| Accuracy class (metering) | 0.2S, 0.5S, 1.0 |
| Accuracy class (protection) | 5P10, 10P10, 5P20, 10P20 |
| Safety factor (FS) | FS5, FS10 (for metering CTs) |
| Rated short‑time thermal current (Ith) | 40 × Ipn for 1 second; 60 × Ipn optional |
| Rated dynamic current (Idyn) | 2.5 × Ith |
| Insulation voltage | 0.66 kV / 1.2 kV / 3.6 kV / 7.2 kV / 12 kV |
| Dielectric test voltage | 3 kV / 28 kV / 42 kV (depending on rated voltage) |
| Core material | Silicon steel or nanocrystalline |
| Mounting type | Cable / Busbar / DIN rail / Panel mount |
| Standards | IEC 61869‑2, IEC 60044‑1, GB 1208, CE |
Where Our Current Transformer Delivers Proven Results with Power Factor Correction Systems
A current transformer is not a one-size-fits-all sensing device. Below are typical scenarios where our current transformer, when paired with a power factor correction capacitor, reduces reactive energy penalties, improves voltage stability, and lowers harmonic distortion — by providing accurate load current signals for the power factor controller to command capacitor switching.
Our current transformer offers precision classes 0.5S or 0.2S, ensuring accurate reactive energy measurement for precise power factor correction and utility-grade billing.
Available from 100 A up to 5000 A, this current transformer covers low to high power applications, from small commercial panels to heavy industrial switchgear.
The split‑core current transformer allows easy retrofit on existing cables without disconnecting power, significantly reducing installation downtime and labor costs.
Designed for crowded electrical panels, ZHIMING‘s current transformer features a space‑saving footprint while maintaining high insulation and thermal performance.
Our dual‑winding current transformer provides separate outputs for metering (0.5 class) and protection (5P10), enabling both functions from a single device.
Fully certified to IEC 61869‑2 and bearing CE marking, this current transformer meets international safety and performance standards for global acceptance.
A leading power capacitor manufacturer with over 25 years of experience is here to answer all your inquiries—covering any product-related issues, business questions, or service-related concerns.
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A dangerously high voltage will appear across the open terminals, potentially causing insulation breakdown, electric shock, or fire. Always short the secondary terminals before disconnecting a transformator arus from its burden.
Choose a primary current rating slightly higher than the expected maximum load current. For example, for a 400 A maximum load, select a 500/5 A transformator arus. Never use a CT with a primary rating lower than the load current.
Metering CTs (0.2S, 0.5S) maintain accuracy up to 120% of rated current. Protection CTs (5P10, 10P10) maintain accuracy under fault currents up to 10‑20× rated current, but may have lower accuracy at normal loads.
Yes, by using a CT with dual secondary windings: one core for metering (0.5 class) and another for protection (5P10). ZHIMING offers such dual‑output current transformers.
For critical installations, test every 2‑5 years. Basic checks include secondary continuity, insulation resistance, and polarity verification. For revenue metering, follow local utility requirements — often annually.
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