Product Overview
The JSJW-6 / JSJW-10 oil-immersed voltage transformer, also called a potential transformer (PT), is a three-phase, five-limb oil-immersed PT designed for voltage metering, voltage monitoring, residual-voltage detection and relay protection in medium-voltage power systems. It is suitable for AC systems with rated frequency of 50Hz or 60Hz and can be documented for 6kV, 10kV, 11kV and 12kV class projects when the voltage ratio, insulation level and project specification are confirmed.
This product is different from epoxy cast-resin PTs such as JSZW, JSZW3, JDZ and JDZX series. The JSJW series uses a sealed oil tank, porcelain bushings, laminated silicon-steel core and No. 25 transformer oil. The oil-immersed insulation system supports dielectric strength, heat dissipation and long-term insulation stability, making it suitable for utility-style metering and protection applications where oil-insulated PTs are preferred.
Product Type
| Item | Specification |
|---|---|
| Product name | Three-Phase Oil-Immersed Voltage Transformer / Potential Transformer |
| Model series | JSJW-6 / JSJW-10 / JSJW-11 / JSJW-12 |
| Transformer type | Three-phase, five-limb, oil-immersed inductive voltage transformer / PT |
| Structure | Sealed oil tank with porcelain bushings, laminated core and oil-immersed windings |
| Rated voltage class | 6kV, 10kV, 11kV and 12kV class systems by project confirmation |
| Rated voltage ratio | 6000/100V, 10000/100V, 10/√3 : 0.1/√3 : 0.1/3, or project-specified ratio |
| Rated frequency | 50Hz / 60Hz |
| Accuracy classes | 0.2, 0.5, 1, 3 and 6P |
| Residual-voltage winding | da / dn open-delta output for earth-fault detection |
| Insulation medium | No. 25 transformer oil reference |
| Rated insulation level | 7.2/32/60kV for 6kV class; 12/42/75kV for 10kV, 11kV and 12kV class |
| Antipollution class | Class II reference |
| Installation form | Stand type and lying type according to site or cabinet arrangement |
| Typical use | Energy metering, voltage monitoring, relay protection and residual-voltage detection |
| Applicable standards | IEC 61869-3, IEC 61869-1, IEC 60044-2, GB1207-2006 and project-specific requirements |
Product Display
Model Designation
- J: Voltage transformer / potential transformer
- S: Three-phase structure
- J: Oil-immersed insulation structure
- W: Five-limb / five-post core structure
- 6 / 10: Catalogue voltage grade reference in kV
- JSJW-11 / JSJW-12: International voltage-class page wording for 11kV and 12kV class projects, subject to insulation and ratio confirmation
Service Conditions
- Altitude: Not exceeding 1000m unless otherwise agreed
- Outdoor ambient temperature: -25°C to +40°C
- Indoor ambient temperature: -5°C to +40°C
- Relative humidity: Not more than 85%
- Installation site: Free from corrosive gas, severe vibration, conductive dust and abnormal pollution
- Pollution class: Class II reference according to catalogue conditions
- Special environments: Tropical, coastal, high-altitude or high-pollution sites require confirmation of creepage distance, sealing design and insulation coordination
Construction
The JSJW series PT is composed of a sealed oil tank, porcelain bushings, laminated silicon-steel core, primary and secondary windings, residual-voltage winding, grounding bolt, oil drain / filling components and mounting base. The porcelain bushings are installed on the tank cover and connected to the primary terminals. Lifting lugs are provided for handling and installation.
The oil-immersed insulation system supports dielectric strength, heat dissipation and long-term insulation stability. The sealed tank structure helps reduce insulation ageing by limiting exposure of the internal insulation to moisture and contamination. The standard insulating medium is No. 25 transformer oil unless otherwise specified.
Applications
- 6kV, 10kV, 11kV and 12kV class power distribution systems
- Medium-voltage utility substations and industrial distribution rooms
- Voltage measurement and electric energy metering circuits
- Voltage monitoring, signal acquisition and automatic control circuits
- Relay protection and residual-voltage earth-fault detection circuits
- Projects where oil-immersed PTs are preferred over cast-resin voltage transformers
- Indoor or outdoor applications according to selected structure and service condition
Technical Data
The following technical table is organized from the catalogue data and written in international PT terminology. For 11kV / 12kV projects, voltage ratio and insulation level should be confirmed according to the local grid standard.
| Model | Rated
Voltage |
Accuracy
Class |
Limit Output |
Rated
Insulation |
|---|---|---|---|---|
| JSJW-6 | 6000 / 100V or 6/√3 : 0.1/√3 : 0.1/3 |
0.2: by agreement 0.5: 80VA 1: 150VA 3: 320VA 6P: by agreement |
640VA | 7.2 / 32 / 60kV |
| JSJW-10 | 10000 / 100V or 10/√3 : 0.1/√3 : 0.1/3 |
0.2: 60VA 0.5: 120VA 1: 200VA 3: 480VA 6P: by agreement |
960VA | 12 / 42 / 75kV |
| JSJW-11 | 11000 / 110V or 11/√3 : 0.11/√3 : 0.11/3 by agreement |
0.2 / 0.5 / 1 / 3 / 6P by technical agreement |
By agreement | 12 / 42 / 75kV by confirmation |
| JSJW-12 | 12000 / 110V or 12/√3 : 0.11/√3 : 0.11/3 by agreement |
0.2 / 0.5 / 1 / 3 / 6P by technical agreement |
By agreement | 12 / 42 / 75kV by confirmation |
Note: Rated output and accuracy class shall be selected as matched options. Final data shall follow the approved nameplate, test report, PDF drawing or technical agreement.
Wiring Options
The JSJW oil-immersed PT supports three-phase PT wiring with metering secondary output and residual-voltage output. The da / dn terminals are the open-delta residual-voltage output terminals. When there is no earth fault, the residual voltage is normally low. When one phase of the line has an earth fault, the da / dn circuit outputs a residual-voltage signal for relay protection.
| Wiring Method | Configuration | Application Note |
|---|---|---|
| Y / Y / open-delta | Four-winding PT wiring with residual-voltage output | Used for voltage measurement and earth-fault protection where residual-voltage detection is required. |
| Y / open-delta | Three-winding PT wiring with open-delta residual-voltage output | Used for voltage monitoring and residual-voltage relay circuits. |
| Metering secondary | Standard secondary voltage output | Connected to voltage meters, energy meters, monitoring devices or control circuits. |
| Residual-voltage secondary | da / dn terminal output | Used for earth-fault detection and relay protection; do not short-circuit during operation. |
Installation & Safety Notes
Dimensions
| Model | Overall Dimension Reference |
Installation Reference |
|---|---|---|
| JSJW-6 stand type | Tank diameter approx. Ø388mm overall height approx. 706mm |
Bottom mounting reference 248mm 4-Φ18 mounting holes |
| JSJW-10 stand type | Tank diameter approx. Ø472mm overall height approx. 874mm |
Bottom mounting reference 320mm 4-Φ18 mounting holes |
| JSJW lying type | Horizontal tank arrangement | Used where vertical height is limited or site layout requires horizontal installation. |
Dimension data is for preliminary layout only. Final dimensions shall be checked against the approved outline drawing or PDF file.
Safety Notes
- Confirm voltage class, ratio, insulation level, accuracy class and output before production.
- Confirm indoor / outdoor service and stand type / lying type structure.
- Check oil level, sealing condition and grounding connection before energizing.
- PT secondary circuits must not be short-circuited or operated under overload.
- Use suitable fuses or MCBs for secondary-circuit protection.
- De-energize the primary circuit before inspection or maintenance.
Selection Guidelines
- Choose voltage class: JSJW-6 for 6kV, JSJW-10 for 10kV, and JSJW-11 / JSJW-12 only after ratio and insulation confirmation.
- Confirm ratio: Select 6000/100V, 10000/100V, 10/√3 : 0.1/√3 : 0.1/3 or a project-specific ratio.
- Select accuracy: Use 0.2 / 0.5 for metering, 1 / 3 for measurement, and 6P for protection.
- Define residual output: Use da / dn open-delta output for earth-fault detection.
- Check installation: Confirm tank diameter, height, mounting holes, bushing clearance, oil service access and grounding position.