Overview
The BH-0.66 II indoor plastic case current transformer is a window-type low-voltage current transformer designed for accurate current measurement, electrical monitoring, and energy metering in AC distribution systems rated up to 0.66kV. It converts high primary current from a busbar or cable into a standardized 5A secondary signal compatible with meters, relays, and monitoring instruments. Its through-core design eliminates the need for primary winding connections, simplifying installation in live circuits.
Built for indoor use, this CT is commonly installed in low-voltage distribution cabinets, switchgear assemblies, and metering panels across industrial and commercial power systems. The unit features an enclosed plastic housing that provides robust mechanical protection and electrical insulation. Multiple rectangular window apertures—ranging from 30×30 mm to 225×65 mm—ensure compatibility with diverse busbar and cable configurations, making it adaptable to various panel layouts.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Rated voltage | 0.66kV |
| Rated frequency | 50Hz |
| Secondary current | 5A |
| Installation type | Indoor |
| Primary conductor | Busbar or cable (through-window) |
| Insulation class | Low-voltage (≤0.66kV) |
| Construction | Enclosed plastic case |
| Core material | Electrical grade iron |
Model Designation
BH-0.66 II model code breakdown:
- BH / SDH: Product series for low-voltage outgoing cabinet or enclosed current transformer applications
- 0.66: Rated voltage class of 0.66kV
- Window size code: Indicates maximum window width in millimeters (e.g., 100 = 100 mm wide aperture)
- II: Design series or product category identifier
Construction
The BH-0.66 II current transformer features a robust enclosed plastic case that fully encapsulates the magnetic core and secondary winding assembly. The housing is molded from flame-retardant, high-impact thermoplastic material, providing excellent electrical insulation and mechanical durability for indoor environments. Internal components are potted or sealed to prevent moisture ingress and ensure long-term stability. The rectangular window is precisely dimensioned to accommodate standard busbars or multi-core cables without requiring disconnection during installation. This cast-resin-free, plastic-case design offers lightweight handling while maintaining compliance with low-voltage distribution safety requirements.
Technical Parameters
Service Conditions
- Installation location: indoor
- Ambient temperature: -5°C to +40°C
- Relative humidity: not more than 80% under standard conditions
- Altitude: not more than 1000m unless otherwise specified
- Atmospheric condition: no serious pollution in the surrounding air
- Installation environment: should be free from severe vibration, conductive dust, corrosive gas, explosive medium, and heavy moisture.
Technical Parameters
The BH-0.66 II current transformer is designed for low-voltage distribution systems with a rated voltage of 0.66kV and operates at 50Hz. It offers multiple accuracy classes and output ratings depending on the selected primary current range.
Technical Data
| Rated Primary Current (A) |
Rated Secondary Current (A) |
Accuracy Class |
Rated Output (VA) |
|---|---|---|---|
| 150, 200, 250 | 5 | 0.5 | 5 |
| 300, 400, 500, 600 | 5 | 0.2 | 5 |
| 800, 1000, 1500 | 5 | 0.2S | 5 |
| 2000, 3000, 4000 | 5 | 0.5 / 0.5S | 10 |
Installation & Wiring
Outline Dimensions
The BH-0.66 II series features a compact plastic case design suitable for indoor low-voltage distribution applications. Dimensional parameters include window size (a × b), height (h), and overall external dimensions (A × B × H). Refer to the table above for specific values per model. All dimensions are in millimeters and should be verified against the approved engineering drawing prior to cabinet layout or procurement.
Wiring Diagram
Connect the secondary terminals according to the marked polarity (typically labeled as S1 and S2). Ensure the secondary circuit is never left open when the primary conductor is energized. Wiring must comply with the project’s schematic diagram and applicable local electrical codes. For multi-ratio models, select the appropriate tap configuration based on the required current ratio and burden.
Selection & FAQs
Selection Guide
- Select the 150A–4000A ratio from maximum operating current and required metering range.
- Choose a 30×30mm to 225×65mm window based on busbar dimensions and insulation clearance.
- Specify class 0.2, 0.2S, 0.5, or 0.5S according to ratio and accuracy requirements.
- Calculate the complete secondary burden and confirm whether the selected model provides 5VA or 10VA.
- Verify panel layout, conductor alignment, mounting points, polarity, grounding, and terminal accessibility.
Frequently Asked Questions
Q1: Can this 0.66kV current transformer be installed outdoors?
No, this model is strictly designed for indoor installation only. The environment must be free from severe vibration, conductive dust, and corrosive gases. Contact us for outdoor-rated alternatives.
Q2: Which accuracy class is available for 800A primary current?
The 0.2S accuracy class is provided for 800A, 1000A, and 1500A primary currents. It delivers a rated output of 5VA at 5A secondary. Confirm specific metering requirements with our engineering team.
Q3: What is the maximum operating altitude for this indoor CT?
The standard maximum altitude is 1000m. For installations exceeding this elevation, derating or custom design adjustments are required. Technical evaluation is necessary for higher altitudes.
Q4: How are custom primary currents handled outside the 150-4000A range?
Yes, custom primary current ratios are available subject to technical confirmation. Standard ranges cover 150A to 4000A with a 5A secondary. Submit your specific project specifications for a detailed quotation.
Q5: Why must ambient temperature limits be verified before purchasing this CT?
The unit operates safely between -5°C and +40°C with relative humidity not exceeding 80%. Ensure the site remains free from heavy moisture and explosive mediums. Request the full environmental datasheet for strict compliance.
Q6: When should this 0.66kV current transformer be applied in switchgear?
It is applied in 0.66kV, 50Hz low-voltage indoor switchgear and distribution panels. The unit provides reliable current measurement and protection for standard AC systems. Ensure system frequency compatibility during design.