Overview
The AKH-0.66 series split-core current transformers are precision electromagnetic devices engineered for accurate current measurement, energy metering, and protective relaying in low-voltage AC power systems up to 0.66 kV. Their opening-type (split-core) design allows installation around existing conductors without disconnecting primary circuits, making them ideal for retrofit applications. Operating on Faraday’s law of electromagnetic induction, these transformers deliver a galvanically isolated secondary current proportional to the primary current, ensuring safety and signal integrity.
Built with cast-resin insulation and a robust split toroidal core, the AKH-0.66 models offer excellent moisture resistance, mechanical strength, and long-term reliability in indoor switchgear and distribution panels. They support standard 5 A secondary output and are available in multiple aperture sizes—/23, /58, /88, /812, and /816—to accommodate various busbar dimensions and load requirements, while maintaining compliance with GB1208-2006 and IEC60044-1:2003 standards.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| System voltage class | 0.66 kV |
| Rated frequency | 50 Hz |
| Rated secondary current | 5 A |
| Accuracy classes | 0.5 / 1 / 3 (metering & protection) |
| Rated burden | As specified per core (VA) |
| Burden power factor | cosφ = 0.8 lagging |
| Installation type | Split-core (opening type) |
| Applicable standards | GB1208-2006; IEC60044-1:2003 |
Model Designation
- A — Current transformer (Acrel brand prefix)
- K — Opening type / split-core construction
- H — Mutual inductor / transformer
- 0.66 — Voltage class in kV
- /23, /58, /88, /812, /816 — Window aperture size variant code
Construction
The AKH-0.66 series features a split-core design with a precision-machined ring-type magnetic core that ensures minimal air gap when closed, preserving magnetic circuit integrity. The entire assembly is encapsulated in cast-resin insulation, providing high dielectric strength, moisture resistance, and protection against environmental contamination. A secure latching mechanism guarantees reliable core closure during operation. Primary current passes through the central aperture (P1 to P2 direction), while secondary windings terminate at clearly marked S1/S2 terminals, conforming to standard CT polarity conventions for accurate metering and protection functionality.
Technical Parameters
Service Conditions
- Installation environment: Indoor installation only
- Altitude: Not exceeding 1000 m above sea level (higher altitude shall be specified for engineering confirmation)
- Ambient temperature: −5 °C to +40 °C
- Relative humidity: Daily average ≤ 95%, monthly average ≤ 90%
- Environmental conditions: Free from corrosive gases or vapors; free from explosive or flammable media; no severe vibration, mechanical shock, or impact
Technical Parameters
This section provides selection-oriented technical data for the AKH-0.66 series indoor, split-core current transformer used in 0.66 kV class AC systems (50 Hz). Data shown below is intended for preliminary selection of accuracy class combinations, rated burdens, and window aperture sizing.
AKH-0.66/23
| Rated Primary Current (A) |
Accuracy Class-Rated Output (VA) |
Packing | ||
|---|---|---|---|---|
| 0.5 | 1 | 3 | ||
| 100/5 | — | — | 1.5 | 20PCS 36×31.5×26cm 20.5kg |
| 150/5 | — | — | 2 | |
| 200/5 | — | 1.5 | 2.5 | |
| 250/5 | — | 2.5 | 3.75 | |
| 300/5 | 1.5 | 2.5 | 6 | |
| 400/5 | 2.5 | 3.75 | 10 | |
AKH-0.66/58
| Rated Primary Current (A) |
Accuracy Class-Rated Output (VA) |
Packing | ||
|---|---|---|---|---|
| 0.5 | 1 | 3 | ||
| 300/5 | — | 1.5 | 3.75 | 10PCS 42×30×20cm 12kg |
| 400/5 | — | 2.5 | 5 | |
| 500/5 | 1.5 | 2.5 | 10 | |
| 600/5 | 2.5 | 5 | 15 | |
| 750/5 | 3.5 | 5 | 20 | |
| 800/5 | 3.75 | 5 | 20 | |
| 1000/5 | 5 | 10 | 20 | |
AKH-0.66/88
| Rated Primary Current (A) |
Accuracy Class-Rated Output (VA) |
Packing | ||
|---|---|---|---|---|
| 0.5 | 1 | 3 | ||
| 250/5 | — | 1.5 | 3.75 | 10PCS 42×37×20cm 14kg |
| 300/5 | — | 1.5 | 5 | |
| 400/5 | — | 2.5 | 10 | |
| 500/5 | 1.5 | 2.5 | 15 | |
| 600/5 | 2.5 | 5 | 15 | |
| 750/5 | 2.5 | 5 | 20 | |
| 800/5 | 3.75 | 5 | 20 | |
| 1000/5 | 5 | 7.5 | 20 | |
AKH-0.66/812
| Rated Primary Current (A) |
Accuracy Class-Rated Output (VA) |
Packing | ||
|---|---|---|---|---|
| 0.5 | 1 | 3 | ||
| 500/5 | — | 2.5 | 12.5 | 10PCS 43×38×24cm 16kg |
| 600/5 | — | 2.5 | 15 | |
| 750/5 | 2.5 | 5 | 12.5 | |
| 800/5 | 2.5 | 5 | 20 | |
| 1000/5 | 3.75 | 7.5 | 20 | |
| 1200/5 | 5 | 10 | 25 | |
| 1250/5 | 5 | 10 | 30 | |
| 1500/5 | 7.5 | 10 | 30 | |
| 1600/5 | 7.5 | 10 | 30 | |
| 2000/5 | 7.5 | 15 | 30 | |
AKH-0.66/816
| Rated Primary Current (A) |
Accuracy Class-Rated Output (VA) |
Packing | ||
|---|---|---|---|---|
| 0.5 | 1 | 3 | ||
| 1000/5 | 5 | 10 | 20 | 5PCS 52.5×30×23cm 19kg |
| 1200/5 | 7.5 | 10 | 25 | |
| 1600/5 | 7.5 | 10 | 25 | |
| 2000/5 | 10 | 15 | 25 | |
| 2500/5 | 15 | 20 | 25 | |
| 3000/5 | 20 | 25 | 30 | |
| 4000/5 | 20 | 25 | 30 | |
| 5000/5 | 20 | 25 | 30 | |
Installation & Wiring
Outline Dimensions
The dimensional drawings illustrate the external profile and window aperture of each model. For AKH-0.66/23, the window aperture measures 21mm × 32mm with overall dimensions of 89mm × 111mm × 60mm. Models /58, /88, /812, and /816 feature progressively larger apertures and housings to accommodate higher conductor sizes, with specific dimensions provided in the technical table (a = window width, b = window height; A, B, C, D, H = external dimensions).
Wiring Diagram
The wiring diagram shows the correct polarity orientation for installation: primary current flows from P1 to P2, and the secondary output is taken from terminals S1 (positive) and S2 (negative). Connect S1 and S2 to the corresponding input terminals of the metering or protection device, ensuring consistent polarity throughout the circuit to maintain measurement accuracy and system safety.
Selection & FAQs
Selection Guide
- Select the 100A–5000A ratio from the conductor’s operating current and required measurement range.
- Choose /23, /58, /88, /812, or /816 by cable or busbar dimensions and installation clearance.
- Specify class 0.5, 1, or 3 and confirm the available VA output for the selected ratio and aperture.
- Calculate the connected-device and cable-loop burden and keep it within the model rating.
- Confirm split-core orientation, mating-surface cleanliness, latch closure, polarity, grounding, and terminal access.
Frequently Asked Questions
Q1: Can this 0.66 kV split-core current transformer be used in 1kV systems?
No, it is strictly designed for 0.66 kV class AC systems operating at 50 Hz. Using it in higher voltage systems requires factory confirmation for alternative models.
Q2: What are the ambient temperature limits for indoor installation?
The ambient temperature must remain between −5 °C and +40 °C. Ensure the installation environment is free from corrosive gases and severe mechanical vibrations.
Q3: Which accuracy class and rated output for a 200/5A primary current?
For 200/5A, you can select Class 1 at 1.5 VA or Class 3 at 2.5 VA. Specify your exact accuracy and burden requirements during ordering.
Q4: Can this transformer be installed at altitudes above 1000 meters?
Standard models are rated for altitudes not exceeding 1000 m above sea level. For higher altitudes, please contact us for engineering confirmation and custom specifications.
Q5: Are routine factory tests provided before shipment?
Standard factory testing protocols apply to all units. Please contact our sales team for detailed test reports and specific certification requirements for your project.
Q6: What applications is the AKH-0.66 series current transformer suitable for?
It is designed for indoor current measurement in 0.66 kV AC power distribution systems. The split-core design enables easy retrofitting; specify conductor dimensions for exact fitment.