Overview
The JDZW-20 and JDZW2-20 outdoor cast-resin voltage transformers are precision electromagnetic instruments engineered for accurate voltage measurement, energy metering, and relay protection in 20kV medium-voltage AC power systems. These transformers operate on electromagnetic induction principles to deliver galvanically isolated secondary signals proportional to the primary system voltage.
Designed for reliable outdoor service, they feature fully enclosed epoxy resin insulation that ensures long-term performance under harsh environmental conditions while eliminating fire hazards and maintenance associated with oil-filled alternatives.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| System voltage class | 20 kV class (outdoor) |
| Rated primary voltage | 20 kV / √3 (line-to-ground) |
| Rated secondary voltage | 100 V / √3 (standard) |
| Rated frequency | 50 Hz or 60 Hz |
| Accuracy classes | 0.2 / 0.5 |
| Rated burden | 30 VA, 50 VA, or 80 VA per winding |
| Limit output capacity | 800 VA |
| Burden power factor | cosφ = 0.8 (lagging) |
| Rated voltage factor | 1.2 Un continuous / 1.9 Un for 30 seconds |
| Insulation level (Um/Ud/Uac) | 24 / 70 / 125 kV |
Model Designation
- J: Voltage transformer (VT)
- D: Single-phase
- Z: Pillar (post) type mounting
- W: Outdoor installation design
- 20: Voltage class (kV)
- R: Epoxy resin casting (fully enclosed insulation)
Construction
The JDZW-20 and JDZW2-20 utilize a pillar-type, fully enclosed epoxy resin cast structure optimized for outdoor substation environments. This solid insulation system provides excellent resistance to UV radiation, moisture, pollution, and mechanical stress, ensuring stable dielectric performance over decades of service. The absence of liquid insulation eliminates leakage risks, fire hazards, and routine maintenance.
Internally, laminated silicon steel cores and Class H thermal-rated windings ensure low losses, high linearity, and reliable operation across the full burden range. A weatherproof terminal box with anti-theft features protects secondary connections, while the robust steel base supports flexible mounting orientations in switchyards and distribution substations.
Technical Parameters
Service Conditions
- Installation: Outdoor (IP-rated)
- Altitude: <= 1000 m
- Ambient temperature: -25 deg C to +40 deg C
- Relative humidity: Daily average <= 95%, monthly average <= 90%
- Pollution level: Class II (Class III/IV optional)
- Environmental: Resistant to UV, industrial/coastal atmospheres; no severe vibration
Technical Data
| Type | Rated Voltage Ratio (kV) |
Accuracy Class |
Rated Secondary Load (VA) |
Limit Output (VA) |
Rated Insulation Level (kV) |
|---|---|---|---|---|---|
| JDZW-20 | 20/0.1 | 0.2 | 30 | 800 | 24/70/125 |
| 0.5 | 80 | ||||
| JDZW2-20 | 20/0.1/0.1 | 0.2 / 0.5 | 30/30 or 30/50 | 800 | 24/70/125 |
| 0.5 / 0.5 | 50/50 |
Installation & Wiring
Installation Diagram
The transformer is mounted vertically or horizontally using the integrated four-hole steel channel base. Primary connection is made at terminal 1U with adequate clearance to grounded structures. Secondary terminals are accessed via the sealed junction box. Ensure proper grounding of the base and one point of the secondary circuit per safety standards.
Outline Dimensions
| Dimension | Value (mm) |
|---|---|
| Total height | 850 |
| Base width | 220 |
| Base length | 300 |
| Bolt hole pattern | 200 x 150 |
| Primary terminal height | 780 |
| φ Creepage distance | = 630 mm (Class II) |
Selection & FAQs
Selection Guide
- Choose JDZW-20 for single-function applications (metering OR protection).
- Choose JDZW2-20 for dual independent secondaries (metering AND protection with galvanic isolation).
- Specify 0.2 class accuracy for revenue-grade metering; 0.5 class for general monitoring and protection.
- Select rated burden (30/50/80 VA) based on total connected load including wiring impedance.
- For altitudes >1000 m or heavy pollution (Class III/IV), request enhanced creepage and insulation.
- Confirm local grid requirements for grounding, fusing, and terminal configuration at order stage.
Frequently Asked Questions
Q1: Can this 20kV voltage transformer be installed in coastal areas?
Yes, it is suitable for coastal atmospheres. The cast-resin housing is UV-resistant and rated for Class III/IV pollution levels upon request. Confirm specific pollution class during ordering.
Q2: Which secondary accuracy class is available for the JDZW2-20 model?
The JDZW2-20 offers 0.2/0.5 or 0.5/0.5 accuracy classes. Rated secondary loads range from 30/30 VA to 30/50 VA depending on the selected class. Contact us for specific ratio configurations.
Q3: What is the rated insulation level for these 20kV transformers?
Both JDZW-20 and JDZW2-20 models feature a 24/70/125 kV rated insulation level. This ensures reliable performance in outdoor switchgear up to 1000m altitude. Verify higher altitude requirements with our engineering team.
Q4: Can the pollution level be customized for harsh industrial environments?
Yes, the standard pollution level is Class II, but Class III and IV are optional. This ensures reliable performance in severe industrial atmospheres. Specify your exact environmental conditions during the inquiry stage for factory confirmation.
Q5: Which international standards apply to these outdoor voltage transformers?
Applicable international standards and specific compliance certifications are subject to confirmation based on your region. Please contact our sales team with your project specifications for detailed documentation.
Q6: Are these cast-resin voltage transformers suitable for outdoor metering applications?
Yes, the JDZW series is specifically designed for outdoor voltage measurement and protection. The fully enclosed cast-resin insulation provides excellent moisture and UV resistance. Confirm exact metering requirements with our technical department.
Q7: What is the maximum operating altitude for this outdoor voltage transformer?
The standard maximum installation altitude is 1000 meters. For projects exceeding this elevation, derating factors or special design modifications apply. Submit your site altitude data for factory evaluation.