Overview
The JSZW3-6 / JSZW3-10 / JSZW3-11 / JSZW3-12 is an indoor three-phase semi-enclosed epoxy cast-resin voltage transformer designed for 6kV, 10kV, 11kV and 12kV class medium-voltage systems. It features a compact, integrated three-phase structure with windings concentrically wound on a cold-rolled silicon steel core and fully encapsulated in epoxy resin for enhanced insulation stability and mechanical robustness.
This voltage transformer supports dual functionality with metering accuracy classes of 0.2, 0.5 or 1 and protection/residual voltage classes of 3P or 6P. It is suitable for voltage measurement, energy metering, relay protection, and residual voltage detection in 50Hz or 60Hz AC systems where the neutral point is not effectively grounded. The design aligns with IEC standards and is widely used in switchgear applications across international markets including Southeast Asia, the Middle East, and Africa.
Key Ratings Snapshot
| Parameter | Rating |
|---|---|
| Voltage class | 6kV, 10kV, 11kV, 12kV |
| Rated frequency | 50Hz / 60Hz |
| Typical voltage ratio | 6kV/√3 : 100V/√3 : 100V/3; 10kV/√3 : 100V/√3 : 100V/3; 11kV/√3 : 110V/√3 : 110V/3 |
| Metering accuracy class | 0.2, 0.5, 1 |
| Protection accuracy class | 3P, 6P |
| Maximum output | 600VA (reference) |
| System grounding | Non-effectively grounded neutral |
| Insulation type | Epoxy cast-resin |
| Phase configuration | Three-phase integrated |
| Installation type | Type A (side) or Type B (base) |
| Residual voltage winding | Yes (open-delta compatible) |
| Application standard | IEC-compliant medium-voltage systems |
Model Designation
- J: Voltage transformer
- S: Three-phase
- Z: Cast-resin insulated
- W: Indoor type
- 3: Design sequence number
- -6 / -10 / -11 / -12: Rated primary voltage class in kV (6kV, 10kV, 11kV, 12kV)
Construction
The JSZW3 series features a three-phase integrated construction with all phases fixed together into a single compact unit. The magnetic circuit employs a side-iron core-type structure made from high-permeability cold-rolled silicon steel sheets. The primary winding, secondary metering winding, and residual-voltage winding are concentrically arranged on the core limb and fully embedded in epoxy cast-resin insulation. This semi-enclosed casting provides excellent dielectric strength, moisture resistance, and mechanical durability. Terminal A of the primary winding is fully insulated, while terminal N is not, consistent with its application in non-effectively grounded systems. The assembly is available in two mechanical configurations: Type A with side-mounting holes on the iron-core clamp, and Type B with a base plate for bottom installation—both suited for secure integration into indoor switchgear panels.
Technical Parameters
Service Conditions
- Installation location: indoor medium-voltage switchgear
- Rated frequency: 50Hz / 60Hz
- Ambient temperature: -5°C to +40°C
- Suitable system: neutral point not effectively grounded or isolated-neutral systems
- Installation environment: should be free from severe vibration, conductive dust, corrosive gas, explosive medium and heavy pollution.
- Special conditions: for high altitude, high humidity, tropical climate or special utility requirements, technical confirmation is recommended before ordering.
Technical Parameters
The JSZW3 series are three-phase semi-enclosed epoxy cast-resin inductive voltage transformers designed for indoor 6kV, 10kV, 11kV, and 12kV systems. They operate within an ambient temperature range of -5°C to +40°C, comply with IEC 61869 and GB/T 20840 standards, and support metering accuracy classes up to 0.2 and protection classes up to 6P, with a maximum output of 600VA.
| Type | Rated transformation ratio(kV) |
Accuracy class / Rated output (VA) |
Max. output (VA) |
|
|---|---|---|---|---|
| Accuracy class |
Rated output (VA) |
|||
| JSZW3-6 | 6000/√3 : 100/√3 : 100/3 | 0.2/6P(3P) | 45/120 | 600 |
| 0.5/6P(3P) | 90/120 | |||
| 1.0/6P(3P) | 150/120 | |||
| JSZW3-10 | 10000/√3 : 100/√3 : 100/3 | 0.2/6P(3P) | 60/120 | 600 |
| 0.5/6P(3P) | 150/120 | |||
| 1.0/6P(3P) | 240/240 | |||
Installation & Wiring
Outline Dimensions
The outline dimensions provide key reference values for switchgear layout and mounting, including phase spacing (139 ± 1mm), overall width (487mm), installation hole spacing (445 ± 1mm), overall height (270 ± 3mm), and depth (195mm). Long mounting holes are specified as 4-20 × 13mm. These dimensions are for preliminary planning; final dimensions must be verified against the approved outline drawing.
Wiring Diagram
The wiring diagram shows terminal markings for primary and secondary connections. Primary terminals are labeled A, B, C, and N. Secondary windings are marked according to standard voltage transformer notation, with terminals for metering and protection circuits clearly indicated. Terminal N is not fully insulated and must be connected strictly in accordance with the approved design. The system grounding method must be confirmed before selecting the appropriate wiring configuration.
Selection & FAQs
Selection Guide
- Select the appropriate voltage class (6kV, 10kV, 11kV, or 12kV) based on your system requirements and project specifications.
- Choose between Type A (side-mounted with iron-core clamp holes) or Type B (base-mounted) depending on your switchgear cabinet design and available mounting space.
- Determine the required accuracy class—3P for high-precision protection applications or 6P for general protection and residual-voltage functions.
- Specify whether a residual-voltage winding is needed for earth-fault detection in non-effectively grounded systems.
- Confirm rated output, insulation level, wiring diagram, applicable standards, and certification requirements when placing an order.
Frequently Asked Questions
Q1: Can this voltage transformer be used in ungrounded neutral systems?
Yes, it is specifically designed for isolated-neutral or ungrounded systems. It supports 6kV to 12kV indoor switchgear applications. Please confirm your exact system grounding requirements before ordering.
Q2: What are the indoor installation environment requirements for this epoxy cast-resin transformer?
The installation environment must be free from severe vibration, conductive dust, corrosive gases, and explosive mediums. It operates between -5°C and +40°C. Contact us for technical confirmation if installing in high humidity or polluted areas.
Q3: Which accuracy class and maximum output does this three-phase transformer support?
It supports metering accuracy classes up to 0.2 and protection classes up to 6P. The maximum output is rated at 600VA. Specify your exact burden requirements for factory configuration.
Q4: Which international standards does the JSZW3 series voltage transformer comply with?
The JSZW3 series fully complies with IEC 61869 and GB/T 20840 standards. It is suitable for 50Hz and 60Hz rated frequency systems. Request the specific test certificates for your project during procurement.
Q5: Can we order this transformer for high altitude or tropical climate conditions?
Yes, but technical confirmation is required before ordering for special conditions. Standard models are rated for -5°C to +40°C. Contact our sales team to discuss customized designs for high altitude or extreme humidity.
Q6: What type of voltage transformer is the JSZW3 series?
It is a three-phase, semi-enclosed, epoxy cast-resin inductive voltage transformer. Designed for indoor medium-voltage switchgear, it operates on 6kV to 12kV systems. Review the technical datasheet for exact dimensional parameters.
Q7: How does the rated transformation ratio work for the 6kV model?
The JSZW3-6 model features a primary to secondary ratio of 6000/√3 : 100/√3 : 100/3. This ensures accurate voltage step-down for metering and protection relays. Verify the exact ratio needed for your specific switchgear design.