Overview
The BH-0.66 III indoor plastic case current transformer is a window-type low-voltage current transformer engineered for accurate current measurement, metering, and electrical monitoring in AC distribution systems up to 0.66kV. Its design allows the primary conductor or busbar to pass directly through a rectangular window, while the secondary winding delivers a standardized 5A output compatible with common meters and monitoring devices.
Ideal for installation in indoor environments such as low-voltage switchgear, distribution cabinets, and metering panels, this CT series supports flexible integration with various busbar layouts. Multiple aperture sizes accommodate diverse cable and busbar configurations, ensuring adaptability across industrial and commercial power distribution applications.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Rated voltage | 0.66kV |
| System frequency | 50Hz |
| Secondary current | 5A |
| Primary current range | As per model variant |
| Accuracy class | 0.5, 1, or 3 (depending on application) |
| Insulation class | Low-voltage, plastic-enclosed |
| Installation type | Indoor, fixed-mount |
| Core material | Laminated silicon steel |
| Housing material | Flame-retardant plastic |
| Window type | Rectangular, through-core |
| Operating temperature | -25°C to +55°C |
| Standards compliance | IEC 61869-2, GB/T 20840 |
Model Designation
B – Enclosed / plastic case structure
H – Current transformer
0.66 – Rated voltage class: 0.66kV
III – Product category / design series
50×50, 60×50, etc. – Window aperture size (width × height in mm) for busbar or cable installation
Construction
The BH-0.66 III features a robust, flame-retardant plastic housing that fully encloses the magnetic core and secondary winding, providing reliable electrical insulation and mechanical protection. The core is constructed from high-permeability laminated silicon steel to ensure accurate current transformation with minimal losses. The window-type design eliminates the need for primary winding connections—the primary conductor simply passes through the insulated aperture. All models are designed for indoor use only, with no outdoor or weather-resistant rating. The secondary terminals are accessible via screw-type connectors, enabling secure and stable wiring to meters or monitoring equipment.
Technical Parameters
Service Conditions
- Installation location: indoor environment
- Altitude: not more than 1000m unless otherwise specified
- Ambient temperature: -5°C to +40°C
- Environmental requirements: The installation environment should be free from severe vibration, conductive dust, corrosive gas, explosive medium, and heavy pollution.
- Special conditions: For special operating conditions, technical confirmation is recommended before ordering.
Technical Parameters
The BH-0.66 III indoor plastic case current transformer is designed for low-voltage distribution systems, offering a range of current ratios, accuracy classes, and burden ratings to suit various metering and protection applications.
General Technical Data
| Item | Specification |
|---|---|
| Rated voltage | 0.66kV / 660V |
| Rated frequency | 50Hz |
| Rated primary current | 150A to 5000A, depending on selected model and ratio |
| Rated secondary current | 5A |
| Accuracy class | 0.5, 0.5S, 0.2; other classes according to order requirements |
| Rated burden | 5VA, 10VA, 20VA, 40VA depending on current ratio and specification |
| Insulation level | Secondary winding to ground insulation resistance ≥10MΩ |
| Power-frequency withstand voltage | 3kV, 1 minute |
| Ambient temperature | -5°C to +40°C |
| Installation altitude | ≤1000m under standard service conditions |
Rated Burden and Accuracy
| Rated Primary Current (A) |
Rated Burden (VA) |
Accuracy Class |
|---|---|---|
| 150–250 | 5 | 0.5 |
| 300–400 | 10 | 0.5 |
| 500–800 | 10 | 0.5S |
| 1200–1500 | 20 | 0.2 |
| 2000–5000 | 40 | 0.2 / 0.5 / 0.5S depending on specification |
Installation & Wiring
Installation Diagram
The BH-0.66 III current transformer is designed for mounting on standard DIN rails or directly onto panel backplates using the provided fixing holes. Ensure adequate clearance around the unit for ventilation and wiring access. The primary conductor (busbar or cable) must pass centrally through the window aperture without mechanical stress on the CT body. Confirm dimensional compatibility between the selected model’s aperture (a × b) and the conductor cross-section before installation.
Wiring Diagram
Connect the secondary terminals according to polarity markings: S1 is the output terminal toward the measuring instrument, and S2 must be reliably grounded at a single point. Never leave the secondary circuit open during operation—this can cause dangerous overvoltages and damage the CT. Use stranded copper wire with appropriate insulation rating for secondary connections, and ensure tight terminal screws to prevent overheating.
Selection & FAQs
Selection Guide
- Select the 150A–5000A primary ratio from the busbar load and required measurement range.
- Choose the rectangular window by conductor width, thickness, insulation clearance, and cabinet space.
- Specify class 0.2, 0.5, or 0.5S according to ratio availability and metering requirements.
- Calculate total burden and select the available 5VA–40VA output for the chosen configuration.
- Confirm DIN-rail or panel mounting, busbar alignment, polarity, grounding, and secondary terminal access.
Frequently Asked Questions
Q1: Is this indoor current transformer suitable for outdoor installation?
No, this BH-0.66 III model is strictly for indoor use. It requires ambient temperatures between -5°C and +40°C without corrosive gases. Contact us for outdoor alternatives.
Q2: Which accuracy class should I select for power metering?
Choose 0.5 or 0.5S class for standard measurement, and 0.2 for high-precision applications. Rated burden ranges from 5VA to 40VA depending on the current ratio. Specify your exact requirements during ordering.
Q3: What is the maximum primary current rating available?
The maximum rated primary current is 5000A. The standard range covers 150A to 5000A with a fixed 5A secondary current. Custom ratios are subject to technical confirmation.
Q4: Where are these 0.66kV low-voltage current transformers typically applied?
They are applied in indoor low-voltage AC distribution systems for current measurement and protection. The rated insulation voltage is 0.66kV at 50Hz. Ensure the installation environment is free from severe vibration.
Q5: Are factory testing reports provided before shipment?
Yes, standard routine tests are performed on all units prior to dispatch. Specific certification or specialized test reports are subject to confirmation. Please specify your testing requirements when placing the order.
Q6: How long is the lead time for custom ratios?
Standard models ship according to our regular production schedule. Custom current ratios and specific burden ratings require additional manufacturing time. Contact our sales team for exact delivery details.
Q7: When should I request technical confirmation for special operating conditions?
Request confirmation when altitude exceeds 1000m or temperatures fall outside -5°C to +40°C. The environment must also be free from conductive dust and corrosive gases. Submit your site details for engineering review.