Product Overview
The UNZ10 / UNZ2-12 fully enclosed epoxy cast-resin voltage transformer is an indoor medium-voltage VT/PT designed for high-voltage switchgear and distribution panels. It is used in 6kV, 10kV and 12kV class power systems for voltage measurement, energy metering, voltage monitoring and relay protection.
The product adopts a fully enclosed epoxy resin casting structure. The primary winding, secondary winding and iron core are cast inside the resin body to improve insulation stability, moisture resistance and pollution resistance. Compared with compact single-phase pillar-type VTs, this model is more suitable when the project requires a larger output capacity and a stronger enclosed insulation structure.
Product Display
Application Position
UNZ10 / UNZ2-12 is normally installed in the voltage transformer compartment of indoor medium-voltage switchgear. It provides secondary voltage signals to energy meters, voltage monitoring devices, protection relays and control circuits. The wiring scheme can be selected according to the switchgear design, such as V/V connection or Y/Y/Δ connection.
Main Applications
- 6kV, 10kV and 12kV indoor medium-voltage switchgear
- Voltage measurement and voltage monitoring circuits
- Energy metering systems
- Relay protection voltage input circuits
- Switchgear requiring higher secondary burden capacity
- V/V or Y/Y/Δ voltage transformer wiring applications
Key Specifications
| Item | Specification |
|---|---|
| Model series | UNZ10 / UNZ2-12 / UNZ2-12/3K/266 |
| Product type | Indoor voltage transformer / potential transformer |
| Insulation structure | Fully enclosed epoxy cast-resin insulation |
| Installation | Indoor switchgear installation |
| Applicable system voltage | 6kV, 10kV and 12kV class systems |
| Rated frequency | 50Hz / 60Hz |
| Ambient temperature | -5°C to +40°C |
| Rated insulation level | 12/42/75kV for the listed 10kV ratio configuration |
| Typical secondary output | 100V / 220V configurations according to project design |
| Typical rated output | 0.5/3 — 100/3000VA |
| Max. output | 5000VA |
| Wiring schemes | V/V connection and Y/Y/Δ connection |
| Standards | GB20840.3-2013, IEC61869-3:2011, GB1207-1997 and project-specific requirements |
Application Fit
Suitable For
- Indoor 6kV, 10kV and 12kV switchgear systems
- Projects requiring fully enclosed cast-resin insulation
- Energy metering circuits with higher secondary burden requirements
- Relay protection systems requiring stable voltage input
- V/V connection and Y/Y/Δ connection applications
- Indoor environments where moisture resistance and pollution resistance are required
Not Recommended For
- Outdoor exposed installation without a suitable enclosure
- High-frequency electronic transformer applications
- Oil-immersed voltage transformer applications
- Compact cabinets where the 78kg product weight or mounting size cannot be accommodated
- Special voltage ratios or outputs without confirmed drawings and technical agreement
Installation Conditions
- Installation location: indoor switchgear or protected indoor electrical cabinet
- Rated frequency: 50Hz / 60Hz power-frequency AC system
- Ambient temperature: -5°C to +40°C
- Atmospheric condition: no severe corrosive gas, conductive dust or heavy pollution accumulation
- Altitude and pollution level: confirm according to project specification and applicable standard
- Maintenance: keep the transformer surface clean and verify terminal fastening during scheduled inspection
Technical Structure
| Component | Description |
|---|---|
| Iron core | High-quality cold-rolled silicon steel sheet core for stable electromagnetic performance |
| Primary winding | Cast inside epoxy resin together with the core and secondary winding |
| Secondary winding | Provides measuring, metering or protection voltage output according to the selected configuration |
| Epoxy resin body | Fully enclosed casting structure for insulation, moisture resistance and mechanical protection |
| Secondary terminal box | Low-voltage output terminals arranged for switchgear wiring and maintenance access |
| Mounting base | Base-mounted structure for indoor switchgear installation |
Model Designation
The following model explanation is written for international product-page use. Final model meaning should follow the manufacturer drawing and nameplate.
- UNZ: Indoor epoxy cast-resin voltage transformer series code.
- 10: Model voltage code commonly used for 10kV system applications.
- 12: 12kV insulation / switchgear class expression for export product pages.
- 3K: Structure or design code, subject to final manufacturer drawing.
- 266: Dimension / design code, subject to final manufacturer drawing.
Technical Data
The following data is organized from the UNZ2-12/3K/266 sample. For international websites, the listed 10kV winding ratio can be presented under a 12kV class product page because the insulation level is 12/42/75kV.
| Rated Voltage Ratio | Accuracy Class and Rated Output | Max. Output | Rated Insulation Level | Rated Frequency |
|---|---|---|---|---|
| 10/√3 : 0.1/√3 : 0.22 | 0.5/3 — 100/3000VA | 5000VA when matched with 3000VA output |
12/42/75kV | 50Hz / 60Hz |
| 10 : 0.1 : 0.22 | 0.5/3 — 100/3000VA |
Technical notes:
- One transformer is supplied with one selected accuracy class and rated output combination.
- The 0.22kV secondary output should be confirmed according to the project metering or auxiliary circuit design.
- If the required parameters exceed the listed scope, they should be confirmed by technical agreement between manufacturer and purchaser.
- The product should be described as a 50Hz / 60Hz power-frequency voltage transformer, not as a high-frequency transformer.
Installation and Dimensions
Dimension Reference
| Item | Reference Value |
|---|---|
| Overall base length | 470mm |
| Main mounting length | 410mm |
| Top body spacing reference | 280 ±1mm |
| Bottom reference length | 420 ±2mm |
| Base width | 250mm |
| Primary terminal bolts | 2-M10 |
| Secondary terminal fixing | 4-M6 |
| Approximate weight | 78kg |
Terminal and Wiring Notes
- Confirm primary terminal position, cable direction and insulation clearance before switchgear design.
- Confirm the secondary output terminal arrangement according to the selected wiring scheme.
- V/V wiring can be used for voltage measurement and metering applications.
- Y/Y/Δ wiring can be used when residual-voltage or protection-related secondary output is required.
- Grounding and terminal polarity must be checked before commissioning.
Compliance and Testing
The product information references GB20840.3-2013, IEC61869-3:2011 and the older GB1207-1997 voltage transformer standard. For export projects, the applicable standard should be confirmed in the technical agreement.
Typical Routine Tests
- Visual inspection and nameplate verification
- Ratio verification
- Polarity and terminal marking check
- Accuracy test at specified burden
- Partial discharge test according to applicable standard
- Power-frequency withstand or induced withstand voltage test according to design
- Insulation resistance test
- Secondary terminal and wiring verification
Engineering Notes
- Use the 12kV class expression for export pages when the listed insulation level is 12/42/75kV.
- Select this model when a higher secondary output capacity is required compared with compact metering-only VTs.
- Confirm whether the project requires V/V connection or Y/Y/Δ connection before production.
- Check the 78kg weight and base mounting size before cabinet layout approval.
- Confirm whether 0.22kV secondary output is used for auxiliary power, monitoring or project-specific circuits.
- For 6kV system applications, confirm the correct insulation level and voltage ratio before ordering.
Selection Guide
For international voltage matching: Use the 12kV class expression for 10kV / 11kV systems when the insulation level is 12/42/75kV. For 6kV / 6.6kV systems, confirm the corresponding 7.2kV insulation class and voltage ratio before production.
For output capacity selection: Choose UNZ10 / UNZ2-12 when the connected secondary burden is higher than a standard metering VT. The sample lists 0.5/3 — 100/3000VA and maximum output up to 5000VA, which should be checked against meter, relay, monitoring and auxiliary loads.
For wiring scheme selection: Use V/V connection for standard three-phase voltage measurement and energy metering. Use Y/Y/Δ connection when the system requires residual-voltage monitoring, insulation supervision or protection-related secondary circuits.
For switchgear compatibility: Confirm cabinet depth, mounting holes, primary cable direction, secondary terminal box position, ventilation space and the approximate 78kg product weight before approving the panel layout.
For procurement and GEO clarity: State the model, voltage class, actual voltage ratio, secondary output, rated burden, wiring method and standard reference in one clear specification line. This helps engineers, AI search systems and procurement teams identify whether the product matches their project.