Product Overview
Functional Definition
The AG5-0.66 series current transformers are precision electromagnetic instruments designed for accurate current measurement and energy metering applications in low-voltage AC power systems (660V class). These transformers utilize electromagnetic induction principles to provide galvanically isolated secondary current signals proportional to primary current.
Key Ratings Snapshot
| Item | Specification (per order / nameplate) |
|---|---|
| System voltage class | 0.66 kV class (indoor distribution and metering applications) |
| Rated frequency | 50 Hz |
| Rated secondary current | 5 A or 1 A |
| Accuracy classes | Metering cores: 0.2, 0.2S, 0.5, 0.5S, 5S |
| Rated burden | 5 VA, 10 VA (as specified) |
| Burden power factor | cosφ = 0.8 (lagging) unless otherwise specified |
| Ambient temperature | -5°C to +55°C |
| Applicable standards | GB1208-2006; IEC 60044-1:2003 |
| Construction type | Indoor plastic case type, fully enclosed |
Product Shows
Working Principle
Operating on Faraday’s law of electromagnetic induction, the transformer features a toroidal magnetic core with primary conductor passing through the aperture and secondary windings wound around the core. The magnetic flux generated by primary current induces proportional voltage in the secondary winding, delivering standardized output current through connected burden.
System Application Position
- Low Voltage Distribution: 660V switchgear, distribution panels, and motor control centers
- Energy Metering: Revenue-grade and sub-metering electricity measurement systems
- Industrial Monitoring: Process control, load monitoring, and power quality analysis
- Building Management: Electrical distribution monitoring in commercial and industrial facilities
Structural Form Overview
Plastic case construction with fully-enclosed design ensures robust insulation performance, moisture resistance, and mechanical protection. The compact mounting configuration provides easy installation in constrained distribution panel environments while maintaining excellent electrical safety margins.
Model Designation
Model Code Explanation
- A — Current transformer (CT)
- G — Plastic case type
- 5 — Design series (model variant identifier)
- 0.66 — Voltage class (kV)
Service Conditions
The AG5-0.66 series current transformers are designed for indoor operation under normal service conditions in low-voltage power systems.
- 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 +55°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
Construction
Construction Design
- Structure: Plastic case type for indoor distribution panels
- Insulation: Fully enclosed plastic housing with integrated insulation system
- Core: Ring-type magnetic core design
- Mounting: Standard DIN rail or panel mounting configuration
The plastic case construction provides reliable insulation properties and resistance to moisture, contamination, and aging for long-term indoor service.
Windings & Terminal Marking
- Primary terminals: P1 / P2
- Secondary terminals: S1 / S2 (or 1S1 / 1S2)
Terminal markings follow standard CT polarity conventions. Under normal operating conditions, the reference current direction is defined from P1 to P2. Correct terminal identification shall be observed to ensure metering performance.
Technical Data
This section provides selection-oriented technical data for the AG5-0.66 series indoor, plastic case 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 primary current ratings.
Definitions: Accuracy class indicates metering precision per IEC/GB standards. Rated output (VA) is specified per secondary winding. Available primary currents provide flexible ratio selection for various load monitoring requirements.
Data Reference
| Rated Primary Current (A) | Rated Secondary Current (A) | Accuracy Classes | Rated Output (VA) |
|---|---|---|---|
| 5, 10, 15, 20, 30, 40, 50, 75 | 5, 1 | 0.2, 0.2S, 0.5, 0.5S, 5S | 5, 10 |
Standards & Normative References
| Standard | Title | Application |
|---|---|---|
| GB1208-2006 | Current Transformers | National standard for CT requirements |
| IEC 60044-1:2003 | Instrument Transformers – Part 1: Current Transformers | International CT requirements |
Factory Testing Compliance
- Routine tests per applicable IEC/GB requirements (including polarity/marking, ratio verification, and accuracy verification per specified class and burden)
- Dielectric tests per insulation coordination requirements and applicable standard
- Visual and dimensional inspection including marking and workmanship conformity
Installation & Dimensions
- Outline dimensions and mounting details are provided in the dimensional drawings.
- The transformer shall be securely mounted using DIN rail clips or panel mounting screws.
- Primary conductor connection may be made via busbar through the aperture or direct connection to P1/P2 terminals.
- Adequate clearance shall be maintained for installation access and heat dissipation.
Outline Dimensions
Safety Notes
- Secondary circuit must never be left open when the transformer is energized, as dangerous high voltage may appear across the secondary terminals.
- During inspection or maintenance, the secondary circuit shall be short-circuited before disconnecting any instruments.
- One point of the secondary circuit should be reliably grounded in accordance with applicable standards.
- All installation and maintenance work shall comply with local electrical safety regulations.
Ordering Information
When placing an order, the required configuration shall be specified according to the local grid requirements, applicable standards, and project technical specification. The following parameters shall be clearly stated for technical confirmation and production release:
- Rated primary current / transformation ratio
- Rated secondary current (5 A or 1 A)
- Application and accuracy requirements (metering accuracy class)
- Rated burden (VA) for the secondary winding
How to Select
1: Determine rated primary current (Ip) based on load rating and expected operating range.
2: Select metering accuracy requirements (e.g., 0.2S / 0.5 for metering).
3: Confirm rated burden (VA) for the secondary circuit based on connected meters and wiring losses.
If local utility or project requirements apply (e.g., terminal arrangement, mounting constraints, documentation language, or required certificates), specify them at the ordering stage. Special configurations shall be confirmed by technical agreement and final data sheet prior to production.
FAQs
Q1: How to select CT ratio and rated primary current for a 660V low voltage current transformer?
A: Select CT ratio / rated primary current (Ip) from load continuous current rating and required measurement range, then verify against distribution panel design and metering requirements.
Q2: How are metering accuracy classes specified (IEC 60044 / GB 1208-2006)?
A: Specify accuracy class (0.2, 0.2S, 0.5, 0.5S, 5S) based on metering application requirements per IEC 60044-1 and GB 1208-2006 standards.
Q3: How to determine rated burden (VA) for 1A/5A CT secondary circuits?
A: Rated burden (VA) shall cover total connected load (meter + wiring loss) for 1A or 5A secondary current and shall be confirmed during engineering design.
Q4: What are mandatory secondary handling and polarity requirements (P1/P2, S1/S2)?
A: Do not open-circuit CT secondary under energized primary. Short and ground per project practice; observe terminal marks P1/P2, S1/S2 for correct polarity.
Q5: Which documents govern compliance (IEC/GB, traceability)?
A: Nameplate and factory test report prevail. Unit test certificates are traceable to accredited laboratories per GB1208-2006 and IEC 60044-1:2003.