Overview
The JSZW3-10 series indoor three-phase combined voltage transformers are precision electromagnetic instruments engineered for accurate voltage measurement, energy metering, and relay protection in 10 kV class AC power systems. Utilizing electromagnetic induction, these transformers deliver galvanically isolated secondary voltage signals proportional to the primary system voltage, ensuring reliable performance in medium-voltage indoor switchgear environments.
Built with fully enclosed epoxy resin cast construction, the JSZW3-10 offers maintenance-free operation, superior moisture resistance, and robust mechanical strength. Its compact three-phase integrated design supports space-constrained installations while maintaining critical electrical clearances and creepage distances.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| System voltage class | 10 kV class (indoor) |
| Rated frequency | 50 Hz / 60 Hz |
| Rated voltage ratio | 10000/sqrt(3) : 100/sqrt(3) : 100/sqrt(3) V |
| Winding configuration | Yo/Yo/Delta (JSZW3-10) or Yo/Yo/Yo/Delta (JSZW3-10F) |
| Accuracy classes | 0.2 / 0.5 / 1 (metering); 6P (protection) |
| Rated output | 15 VA (0.2), 30 VA (0.5), 60 VA (1), 50 VA (6P) |
| Maximum output | 300 VA |
| Insulation level | 12/42/75 kV (Um/Ud/Up) |
| Applicable standards | GB 1207; IEC 60044-2 |
| Model variants | JSZW3-10 / JSZW3-10F |
Model Designation
- J: Voltage transformer (VT)
- S: Three-phase combined type
- Z: Cast-resin (epoxy) insulated, fully enclosed structure
- W: Indoor installation
- 3: Design code (platform/iteration)
- 10: Voltage class (kV)
- F: Four-winding configuration (present only in JSZW3-10F)
Construction
The JSZW3-10 features a three-phase combined design with fully enclosed epoxy resin cast insulation, providing excellent dielectric strength, moisture resistance, and long-term stability for indoor applications. The dry-type, oil-free construction eliminates environmental hazards and maintenance requirements associated with liquid-filled units, while ensuring compliance with modern safety and sustainability standards.
Its integral core assembly and base-mounted configuration facilitate secure installation in standard 10 kV switchgear panels. The design maintains precise electrical clearances and creepage distances, supporting reliable operation under normal service conditions without degradation due to contamination, humidity, or aging.
Technical Parameters
Service Conditions
- Installation environment: Indoor only; free from corrosive gases, explosive media, severe vibration, or mechanical shock
- Altitude: <= 3000 m above sea level
- Ambient temperature: -5 deg C to +40 deg C
- Relative humidity: <= 85% (at +20 deg C reference)
- Environmental conditions: No conducting dust; no condensation affecting insulation
Technical Data
| Type | Rated Voltage Ratio (V) |
Accuracy Class & Rated Output (VA) |
Max Output (VA) |
Rated Insulation Level (kV) |
|||
|---|---|---|---|---|---|---|---|
| 0.2 | 0.5 | 1 | 6P | ||||
| JSZW3-10 | 10000/√3 : 100/√3 : 100/√3 | 15 | 30 | 60 | 50 | 300 | 12/42/75 |
| JSZW3-6 | 6000/√3 : 100/√3 | 15 | 30 | 60 | 50 | 300 | 7.2/32/60 |
| JSZW3-3 | 3000/√3: 100/√3 | 15 | 30 | 60 | 50 | 300 | 3.6/20/40 |
Installation & Wiring
Installation Diagram
The transformer must be securely mounted on a stable, level foundation using the designated base fixing holes. Primary terminals connect directly to system busbars or feeders, and the primary neutral (N) must be solidly grounded per applicable standards. Maintain adequate clearance around the unit for insulation integrity, heat dissipation, and service access.
Selection & FAQs
Selection Guide
- Determine system voltage class (e.g., 10 kV, 6 kV) based on distribution network design.
- Select winding configuration: JSZW3-10 (three-winding) for basic metering/protection, or JSZW3-10F (four-winding) for dedicated protection winding and enhanced functional isolation.
- Specify accuracy class per application: 0.2 for revenue metering, 0.5/1 for indication, 6P for protection relaying.
- Calculate and confirm rated burden (VA) for each secondary winding based on connected meters, relays, and wiring losses.
- Verify insulation level (Um/Ud/Up) against system overvoltage coordination and local grid requirements.
- Clearly state model, frequency (50/60 Hz), voltage ratio, accuracy, burden, and insulation level in purchase order.
Frequently Asked Questions
Q1: Can this indoor voltage transformer be installed outdoors?
No, it is strictly for indoor installation. The environment must be free from corrosive gases, severe vibration, and conducting dust. Contact us for outdoor-rated alternatives.
Q2: Which accuracy class is suitable for protective relaying applications?
Select the 6P accuracy class for protection circuits. It provides a rated output of 50 VA under fault conditions. Confirm specific burden requirements with our engineering team.
Q3: What is the rated insulation level for the 10kV model?
The JSZW3-10 model features a 12/42/75 kV insulation level. This ensures reliable performance in 10kV indoor switchgear systems. Request the full type test report for verification.
Q4: Can the primary voltage ratio be customized for 6kV systems?
Yes, the JSZW3-6 model is specifically designed for 6000/√3 : 100/√3 V systems. Custom ratios are subject to factory confirmation. Please provide your exact system parameters for quotation.
Q5: What routine factory tests are performed before shipment?
Standard routine tests include ratio, polarity, and insulation resistance checks. Specific type tests or third-party certifications are subject to confirmation. Contact our sales team for detailed test protocols.
Q6: What is the primary application of this three-phase combined transformer?
It is primarily used for voltage measurement and protective relaying in 3kV to 10kV indoor power distribution networks. Contact us to verify suitability for your specific substation application.
Q7: Is this transformer suitable for high-altitude installations above 3000 meters?
No, the standard design is rated for altitudes up to 3000 meters. For higher elevations, derating or special design modifications are required. Please specify your exact site altitude during inquiry.