Overview
The JDZ12 series single-phase epoxy resin voltage transformers are precision electromagnetic devices engineered for accurate voltage measurement, energy metering, and relay protection in 3-12 kV AC power systems. Utilizing Faraday’s law of electromagnetic induction, these units deliver galvanically isolated secondary voltages proportional to the primary system voltage. Key features include fully enclosed vacuum cast epoxy resin insulation, integrated internal fuse protection matched to short-circuit capacity, and dual secondary outputs: 100 V for instrumentation and 220 V for circuit breaker control.
Designed for reliability in both indoor and outdoor switchgear applications, the JDZ12 series ensures long-term stability, moisture resistance, and mechanical robustness. Its sealed terminal design enhances safety against electric shock and unauthorized access, making it ideal for pad-mounted transformers, ring main units, and medium-voltage distribution networks.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| System Voltage Class | 3 kV / 6 kV / 10 kV |
| Rated Frequency | 50 Hz or 60 Hz |
| Voltage Ratio (JDZ12-10R) | 10000/100/220 V |
| Accuracy Classes | Metering: 0.2, 0.5, 1 : Protection: 6P |
| Rated Output | 15 VA to 60 VA (class dependent) |
| Maximum Output | 500 VA |
| Burden Power Factor | cos phi = 0.8 (lagging) |
| Voltage Factor | 1.2 Un continuous |
| Thermal Class | Class E (75K rise limit) |
| Fuse Protection | Integrated internal fuse |
Model Designation
- J : Voltage transformer (VT/PT)
- D : Single-phase configuration
- Z : Cast-resin (epoxy) insulated, fully enclosed structure
- 12 : Design series
- 10 / 6 / 3 : Voltage class (kV)
- R : Built-in fuse protection
Construction
The JDZ12 series features a support (post) type structure with vacuum cast epoxy resin insulation, providing excellent dielectric strength, moisture resistance, and contamination immunity. The fully enclosed design protects the laminated silicon steel core and windings from environmental stress, ensuring stable performance in harsh indoor or outdoor enclosures. Primary terminals accept 200A elbow-type cable connectors with sealed high-voltage interfaces, while secondary terminals are housed in a sealed box with provisions for anti-tampering lead seals.
Internal fuse integration eliminates the need for external fuses, simplifying installation and enhancing system coordination. The construction meets stringent mechanical and thermal requirements, supporting reliable operation under normal and transient system conditions across the 3-10 kV range.
Technical Parameters
Service Conditions
- Installation environment: Indoor or outdoor (with sealed enclosure)
- Altitude: Not exceeding 2000 m above sea level
- Ambient temperature: -5 deg C to +40 deg C (daily average <= 35 deg C)
- Relative humidity: Daily average <= 95%, monthly average <= 90% (at +20 deg C)
- Environmental conditions: Free from corrosive gases, explosive media; suitable for moderate mechanical stress
Technical Data
| Model | Rated Voltage Ratio (V) |
Accuracy Class 0.2 Output (VA) |
Accuracy Class 0.5 Output (VA) |
Accuracy Class 1 Output (VA) |
Accuracy Class 6P Output (VA) |
Max Output(VA) |
Insulation Level (kV) |
|---|---|---|---|---|---|---|---|
| JDZ12-10R | 10000 / 100 / 220 | 15 | 30 | 60 | 50 | 500 | 12 / 42 / 75 |
| JDZ12-6R | 6000 / 100 / 220 | 15 | 30 | 60 | 50 | 500 | 7.2 / 32 / 60 |
| JDZ12-3R | 3000 / 100 / 220 | 15 | 30 | 60 | 50 | 500 | 3.6 / 25 / 40 |
Installation & Wiring
Installation Diagram
Proper installation ensures safe and accurate operation. Mount the transformer securely using the designated fixing holes. Connect the primary side via a sealed 200A elbow-type cable connector. After wiring secondary terminals, seal the terminal box and apply lead seals as required by utility regulations. Maintain adequate clearance for insulation, heat dissipation, and maintenance access per local electrical codes.
Selection & FAQs
Selection Guide
- Select accuracy class based on application: 0.2 for revenue metering, 0.5 for standard metering, 1 for indication, and 6P for protection relays.
- Ensure total secondary burden (including cable impedance) does not exceed rated VA for the chosen accuracy class.
- Choose model variant (JDZ12-10R/6R/3R) matching your system voltage class and insulation coordination requirements.
- For outdoor use, install within a sealed, weatherproof enclosure to maintain IP rating and terminal integrity.
- Verify ambient conditions (temperature, humidity, altitude); installations above 2000 m require engineering review.
Frequently Asked Questions
Q1: What accuracy class is suitable for protective relaying?
Use the 6P accuracy class for protection applications. It provides a 50 VA output with 12/42/75 kV insulation for the 10kV model. Contact us for specific burden calculations.
Q2: Can this epoxy resin voltage transformer be installed outdoors?
Yes, but only when housed in a sealed enclosure. The JDZ12-10R requires ambient temperatures between -5°C and +40°C. Verify your site’s environmental conditions with our engineering team.
Q3: Which rated voltage ratio fits a 10kV distribution network?
The JDZ12-10R model with a 10000/100/220 V ratio is designed for 10kV systems. It supports up to 500 VA maximum output. Specify your primary voltage during ordering.
Q4: How does altitude affect this voltage transformer’s performance?
Standard models are rated for altitudes not exceeding 2000 m above sea level. For higher elevations, derating or custom design is required. Please consult our technical department for site-specific adjustments.
Q5: What factory tests are performed before shipment?
Routine electrical tests are performed before dispatch to ensure compliance with standard specifications. Specific type test certificates are subject to project requirements. Contact our sales team for detailed test reports.
Q6: Are custom secondary voltage outputs available for special applications?
Standard models feature 100/220 V secondary outputs. Custom voltage ratios can be manufactured based on your specific system design. Submit your detailed technical specifications for factory evaluation.
Q7: Why choose epoxy resin casting for this voltage transformer?
Epoxy resin casting provides excellent moisture resistance and high dielectric strength for indoor switchgear. The JDZ12 series operates reliably in environments free from corrosive gases. Request our full product catalog for more details.