Overview
The JDZ9-20 JDZXF-20, JDZX-20 are 20 kV class indoor epoxy resin voltage transformers designed for accurate voltage measurement, energy metering, and relay protection in medium-voltage AC power systems. Operating on electromagnetic induction principles, it delivers galvanically isolated secondary voltage signals proportional to the primary voltage, enabling safe interfacing with meters, relays, and monitoring equipment.
This single-phase, cast-resin insulated VT features a compact support-type design ideal for installation in indoor switchgear. Its fully enclosed epoxy construction ensures high insulation integrity, moisture resistance, and long-term reliability under normal service conditions.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| System voltage class | 20 kV (indoor) |
| Rated frequency | 50 Hz (60 Hz optional) |
| Rated primary voltage | 20 kV (phase-to-phase) |
| Rated secondary voltage | 100 V or 100/â3 V or 100/3 V |
| Accuracy classes | 0.2 or 0.5 (metering) |
| Rated burden | 20 VA or 50 VA (per winding) |
| Burden power factor | cos phi = 0.8 (lagging) |
| Maximum output capacity | 600 VA |
| Insulation level (Um/ACSD/LI) | 24/65/125 kV |
| Applicable standards | IEC 61869-3, GB/T 20840.3 |
Model Designation
- J: Voltage transformer (VT)
- D: Single-phase design
- Z: Cast-resin (epoxy) insulated, fully enclosed structure
- 9: Design code (platform/iteration)
- 20: Voltage class (kV)
Construction
The JDZ9-20 JDZXF-20, JDZX-20 features a support-type (post) structure with vacuum-cast epoxy resin insulation, providing excellent electrical, mechanical, and environmental performance. The fully enclosed design eliminates contamination risks and ensures stable dielectric properties over time. High-grade silicon steel laminations form the magnetic core, minimizing losses while maintaining accuracy under rated load conditions.
Primary and secondary windings are embedded within the solid epoxy matrix, ensuring complete isolation and resistance to moisture, thermal aging, and tracking. The compact vertical mounting configuration allows easy integration into standard 20 kV indoor switchgear panels with adequate creepage and clearance distances per IEC requirements.
Technical Parameters
Service Conditions
- Installation environment: Indoor only
- Altitude: <= 1000 m above sea level
- Ambient temperature: -5 deg C to +40 deg C
- Relative humidity: <= 95% (non-condensing at +20 deg C)
- Pollution degree: Class II per IEC 60664-1
- Mounting position: Vertical, primary terminals at top
- Environmental restrictions: No corrosive gases, explosive media, severe vibration, or mechanical shock
Technical Data
| Model | PrimaryVoltage Rating | SecondaryConfiguration | Application |
|---|---|---|---|
| JDZ9-20 | 20 kV(phase-to-phase) | Single secondary winding:100 V or 100/√3/100/3 V | Basic metering or protection(isolated neutral systems) |
| JDZF9-20 | 20 kV(phase-to-phase) | Dual secondary windings: 100/100 V | Independent metering and protection(isolated neutral systems) |
| JDZX9-20G | 20/√3 kV(phase-to-ground) | Single secondary + residual voltage winding: 100/√3 V + 100/3 V | Metering/protection + ground fault detection(grounded neutral systems) |
| JDZXF9-20G | 20/√3 kV(phase-to-ground) | Dual secondary + residual voltage winding: 100/√3 V + 100/√3 V + 100/3 V | Independent metering/protection + ground fault detection(grounded neutral systems) |
Installation & Wiring
Installation Diagram
The JDZ9-20 must be vertically mounted on a switchgear base using the provided fixing holes. Primary terminal A connects to the phase conductor; terminal X is the return. Secondary terminals a/x deliver standardized output to connected burden. Ensure minimum clearances per IEC 60071-1 and provide ventilation for heat dissipation.
Outline Dimensions
| Dimension | Value (mm) |
|---|---|
| Total height | 410 |
| Base width | 180 |
| Base depth | 180 |
| Mounting hole pattern | 140 x 140 mm |
| Primary terminal height | 380 |
| phi Mounting hole diameter | 12 |
Selection & FAQs
Selection Guide
- Use JDZ9-20 only in isolated neutral (ungrounded) 20 kV systems with phase-to-phase primary connection.
- Select accuracy class 0.2 for billing-grade metering; 0.5 for general monitoring or protection applications.
- Specify secondary voltage (100 V, 100/â3 V, or 100/3 V) based on connected equipment requirements.
- Calculate total burden (VA) including meters, relays, and wiring losses; ensure it does not exceed rated output.
- Verify ambient conditions (temperature, humidity, altitude) comply with service limits before installation.
- For three-phase systems, order three single-phase units; residual voltage detection is not supported in JDZ9-20.
Frequently Asked Questions
Q1: Which model suits grounded neutral systems for ground fault detection?
The JDZX9-20G and JDZXF9-20G models are designed for grounded neutral systems. They feature a 20/√3 kV phase-to-ground rating and include a residual voltage winding for fault detection. Contact us for specific secondary configurations.
Q2: Can this voltage transformer be installed in outdoor switchgear?
No, this epoxy resin transformer is strictly rated for indoor installation only. It requires an ambient temperature between -5°C and +40°C without corrosive gases. Verify your enclosure environment before ordering.
Q3: What is the required mounting position for the primary terminals?
The transformer must be mounted vertically with the primary terminals positioned at the top. Ensure the installation site is free from severe vibration or mechanical shock. Confirm structural support with your site engineers.
Q4: How do I specify the secondary configuration for basic metering?
Select the JDZ9-20 model for basic metering in isolated neutral systems. It provides a single secondary winding rated at 100 V. Specify your exact voltage requirement during your initial inquiry.
Q5: When can I expect delivery for custom secondary windings?
Standard models ship according to our regular lead times. Custom secondary winding configurations, such as dual windings for independent protection, are subject to factory confirmation. Please contact our sales team for exact delivery schedules.
Q6: Are these 20kV epoxy resin transformers compliant with international pollution standards?
Yes, they are rated for Class II pollution degree per IEC 60664-1. This ensures reliable performance in standard indoor industrial environments with non-condensing humidity up to 95%. Request the full type test report for your project documentation.