Product Overview
The JDG-0.5 / JDG4-0.5 indoor dry-type low-voltage voltage transformer is a single-phase indoor voltage transformer designed for voltage measurement, electrical energy metering, and relay protection in AC circuits with rated voltage up to 0.5kV and rated frequency of 50Hz or 60Hz. It converts the primary voltage into a standardized secondary voltage signal for measuring instruments, energy meters, and protection devices.
The JDG-0.5 and JDG4-0.5 series are dry-type voltage transformers with an iron-core structure. They are suitable for indoor low-voltage switchgear, metering panels, distribution cabinets, and power monitoring systems. The products can be used for measuring line voltage, power, and electrical energy, while also providing voltage signals for relay protection and monitoring equipment.
Product Type
| Item | Specification |
|---|---|
| Product name | Indoor Dry-Type Low Voltage Voltage Transformer |
| Model series | JDG-0.5 / JDG4-0.5 |
| Product structure | Single-phase indoor dry-type voltage transformer |
| Rated voltage class | 0.5kV and below low-voltage AC system |
| Rated frequency | 50Hz / 60Hz |
| Rated voltage ratio | 220/100V, 380/100V, 500/100V; JDG4-0.5 can support wider primary voltage requirements by agreement |
| Installation location | Indoor |
| Typical applications | Voltage measurement, energy metering, power monitoring, relay protection |
Product Display
Main Applications
- Indoor low-voltage AC circuits rated up to 0.5kV
- Voltage measurement circuits in distribution systems
- Electrical energy metering and power monitoring panels
- Relay protection and control circuits requiring voltage signals
- Low-voltage switchgear, distribution cabinets, and metering cabinets
- Instrument power supply and voltage signal isolation for measuring devices
Key Technical Features
- Indoor dry-type structure: Suitable for low-voltage indoor environments where compact installation and convenient maintenance are required.
- Single-phase voltage measurement: Provides a standardized 100V secondary voltage signal for meters, relays, and monitoring devices.
- Multiple voltage ratios: Common voltage ratios include 220/100V, 380/100V, and 500/100V for different low-voltage systems.
- Metering and protection use: Applicable to voltage measurement, electrical energy metering, and relay protection circuits.
- Dry-type insulation design: The coil and core structure are designed for indoor operation without oil insulation.
- Standards compliance: Applicable to GB/T 20840.1, GB/T 20840.3, and related voltage transformer project requirements.
Working Principle
The JDG-0.5 / JDG4-0.5 voltage transformer operates according to electromagnetic induction. The primary winding is connected to the measured low-voltage circuit, and the secondary winding outputs a reduced voltage signal, typically 100V, for meters, instruments, and relay devices. This allows the primary voltage to be measured safely while providing electrical isolation between the power circuit and secondary equipment.
Model Designation
The model code can be interpreted as follows:
| Code | Meaning |
|---|---|
| J | Voltage transformer |
| D | Single-phase structure |
| G | Dry-type design |
| 4 | Design series code for JDG4 type, where applicable |
| 0.5 | Rated voltage class: 0.5kV |
Technical Data
| Item | Specification |
|---|---|
| Rated voltage class | 0.5kV and below |
| Rated frequency | 50Hz / 60Hz |
| Rated voltage ratio | 220/100V, 380/100V, 500/100V |
| Rated secondary voltage | 100V |
| Accuracy class | 0.5, 1, 3 according to selected rated output and application |
| Rated output | JDG-0.5: 25VA / 40VA / 100VA; JDG4-0.5: 15VA / 25VA / 50VA according to accuracy class |
| Limit output | 100VA or 200VA according to selected type and specification |
| Rated insulation level | 3kV |
| Installation location | Indoor |
| Applicable standards | GB/T 20840.1, GB/T 20840.3; GB/T 20840.3-2013 and JJG 314-2010 can be referenced according to project requirement |
Rated Voltage Ratio, Accuracy and Output Reference
| Model | Rated
Voltage Ratio |
Output
0.5 Class (VA) |
Rated
Output 1 Class (VA) |
Rated
Output 3 Class (VA) |
Limit
Output (VA) |
Rated
Insulation Voltage (kV) |
|---|---|---|---|---|---|---|
| JDG-0.5 | 500/100 | 25 | 40 | 100 | 200 | 3 |
| JDG-0.5 | 380/100 | 25 | 40 | 100 | 200 | 3 |
| JDG-0.5 | 220/100 | 25 | 40 | 100 | 200 | 3 |
| JDG4-0.5 | 500/100 | 15 | 25 | 50 | 100 | 3 |
| JDG4-0.5 | 380/100 | 15 | 25 | 50 | 100 | 3 |
| JDG4-0.5 | 220/100 | 15 | 25 | 50 | 100 | 3 |
Note: JDG4-0.5 can also be specified with primary voltage requirements such as 100V to 1140V and secondary voltage requirements such as 100V to 230V by technical agreement.
Service Conditions
- Installation location: indoor
- System voltage: 0.5kV and below
- Rated frequency: 50Hz / 60Hz
- Ambient temperature: -25°C to +40°C for typical service conditions, or according to project specification
- Altitude: not more than 1000m unless otherwise specified
- The installation environment should be free from rain, snow, direct outdoor exposure, severe pollution, and strong vibration.
- For special temperature, altitude, humidity, pollution level, or cabinet layout requirements, technical confirmation is recommended before ordering.
Standards and Compliance
The JDG-0.5 / JDG4-0.5 series voltage transformer is designed for low-voltage voltage measurement and metering applications. It can be supplied according to GB/T 20840.1, GB/T 20840.3, and project-specific technical requirements. For JDG4-0.5, related references such as GB/T 20840.3-2013 and JJG 314-2010 can be applied according to the project acceptance requirement.
Installation and Dimensions
The JDG-0.5 / JDG4-0.5 series adopts an indoor dry-type structure with fixed installation. Different outline structures are available according to product type and voltage ratio. Final dimensions should be confirmed according to the approved drawing before production or cabinet design.
Outline and Installation Reference
| Model | Typical
Structure |
Rated
Voltage Ratio |
Installation
Reference |
Remark |
|---|---|---|---|---|
| JDG-0.5 | Indoor dry-type iron-core structure | 220/100V, 380/100V, 500/100V | Base fixed installation | Confirm final dimensions with approved drawing |
| JDG4-0.5 | Indoor dry-type C-core structure | 220/100V, 380/100V, 500/100V or project-specified ratio | Base fixed installation | Confirm final dimensions with approved drawing |
Unit: mm for dimensional drawings. Final dimensions are subject to confirmed drawing and selected specification.
Connection and Wiring Notes
- Connect the primary terminals according to the marked phase and polarity symbols, such as A and X.
- Connect the secondary terminals according to the marked secondary symbols, such as a and x.
- Confirm the voltage ratio, rated output, and accuracy class before wiring.
- The secondary circuit should be protected with suitable fuses or terminal devices according to the project wiring diagram.
- For three-phase measurement, the transformer can be used in suitable PT connection schemes according to system and metering requirements.
Installation and Safety Notes
- Confirm the product model, voltage ratio, accuracy class, rated output, and installation dimensions before installation.
- Install the voltage transformer in an indoor dry location without rain, snow, or severe pollution.
- Avoid operation under overload conditions beyond the specified rated or limit output.
- Secondary wiring, grounding, and protection should comply with project specifications and local electrical regulations.
- Installation and maintenance should be performed by qualified electrical personnel.
Ordering Information
Please provide the following information when ordering or requesting a quotation:
- Product model: JDG-0.5 or JDG4-0.5
- Rated voltage ratio, such as 220/100V, 380/100V, or 500/100V
- Rated output and required accuracy class
- Rated frequency and operating environment
- Installation dimensions or cabinet layout requirements
- Quantity and application, such as metering, monitoring, or relay protection
- Special requirements for terminals, fuses, labels, drawings, inspection documents, certificates, or packaging
Selection Guidelines
- Confirm system voltage: Select the voltage transformer for indoor AC systems rated up to 0.5kV.
- Confirm voltage ratio: Select 220/100V, 380/100V, 500/100V, or a project-specified ratio according to the measured circuit.
- Select accuracy class: Use 0.5 class for metering or measurement requirements, and 1 or 3 class for general indication or auxiliary applications.
- Check rated output: The total burden of meters, relays, instruments, and wiring should not exceed the rated output of the transformer.
- Confirm limit output: Ensure the selected type meets the required maximum output capacity for the connected circuit.
- Confirm installation space: Check the outline dimensions, terminal position, and cabinet clearance before batch installation.