JDZ-10 Semi-Enclosed Dry-Type Discharge Coil
Product Overview
The JDZ-10 Semi-Enclosed Dry-Type Discharge Coil is a dry-type device specifically designed for reactive power compensation equipment in 10kV AC power systems. It adopts a semi-enclosed epoxy resin cast structure with an integrated iron core and winding assembly. The device features excellent insulation performance, fast discharge capability, and reliable operation. Its primary function is to dissipate residual charge from shunt capacitor banks following de-energization. It also serves as a voltage monitoring and overvoltage protection signal acquisition device. The JDZ-10 is widely applied in indoor reactive power compensation switchgear, shunt capacitor bank complete assemblies, and distribution substations.
Core Product Features
Insulation and Electrical Performance
Semi-Enclosed Dry-Type Insulation Structure: Employs a semi-enclosed design combining epoxy resin casting with air insulation. High-voltage terminals utilize a shed-type insulation structure, providing excellent insulation performance capable of withstanding the 10kV system operating voltage and power-frequency/impulse withstand voltage tests. The oil-free design eliminates leakage and contamination risks, making it suitable for indoor oil-free distribution environments.
Fast Discharge Characteristics: The integrated dedicated discharge winding reduces the residual voltage of the capacitor bank to a safe level within the specified time, meeting the power industry standard requirements for capacitor bank discharge time and ensuring safety during maintenance and operation.
Voltage Monitoring and Protection Function: Provides simultaneous voltage monitoring signals for capacitor bank overvoltage and undervoltage protection, enabling safe and stable operation of reactive power compensation devices.
Low Partial Discharge Design: Advanced casting technology minimizes partial discharge levels, preventing insulation aging caused by long-term partial discharge activity and enhancing the long-term operational reliability of the device.
Structural and Installation Features
Compact Modular Design: The compact, small-footprint structure is compatible with standard 10kV reactive power compensation switchgear installation dimensions, facilitating in-cabinet arrangement.
Clear Terminal Identification: High-voltage terminals are clearly labeled and feature a shed-type insulation structure with excellent anti-pollution flashover performance. Low-voltage terminals are protected by a terminal cover, enabling convenient wiring while preventing miswiring and short circuits.
Flexible Mounting Options: The metal base plate is equipped with fixing holes to support bolt-down installation, compatible with horizontal or vertical mounting inside indoor enclosures. The installation is mechanically secure with excellent vibration resistance.
Operational and Maintenance Features
Maintenance-Free Operation: The dry, oil-free structure eliminates leakage and fire hazards. The high mechanical strength of the epoxy resin cast body provides impact and aging resistance, enabling long-term maintenance-free operation and reducing operational costs.
Wide Temperature Operating Range: Suitable for ambient temperatures from -30°C to +70°C. The epoxy resin maintains stable performance across the full temperature range without risk of embrittlement or deformation, adapting to climatic conditions across different regions.
High-Reliability Design: The winding is wound with enameled copper wire, and the iron core is laminated with high-quality silicon steel sheets. The device features low operating losses, minimal heat generation, and overvoltage withstand capability, capable of sustaining system switching overvoltages and lightning impulse overvoltages.
Technical Parameters (Typical Specifications)
| Parameter Category | Item | Technical Specification |
| Electrical Parameters | Applicable System Voltage | 10kV AC |
| | Rated Frequency | 50Hz | |
| | Rated Primary Voltage | 10/√3 kV | |
| | Rated Secondary Voltage | 100/√3 V (customizable) | |
| | Discharge Time | Residual voltage of capacitor bank reduced to ≤50V within the specified time after de-energization | |
| | Power-Frequency Withstand Voltage (HV Terminal) | 42kV / 1min, no breakdown | |
| | Lightning Impulse Withstand Voltage (Peak) | 75kV, no breakdown | |
| | Partial Discharge Level | ≤10pC | |
| | Insulation Resistance (HV to LV and Earth) | ≥1000MΩ | |
| Structural and Material Parameters | Insulating Medium | Epoxy resin casting + air insulation |
| | Degree of Protection | IP20 | |
| | Mounting Method | Indoor post-type bolt mounting | |
| | Thermal Class of Insulation | Class B (130°C) | |
| Environmental Parameters | Applicable Altitude | ≤2000m (high-altitude customization available) |
| | Operating Ambient Temperature | -30°C to +70°C | |
| | Storage Ambient Temperature | -40°C to +85°C | |
| | Relative Humidity | ≤95% (non-condensing) | |
| Applicable Standards | National Standards | GB/T 11024 Shunt Capacitors for AC Power Systems Having a Rated Voltage Above 1kV; DL/T 653 Technical Requirements for Ordering Discharge Coils for Shunt Capacitors |
Application Scope
Applicable Voltage Class: 10kV indoor AC power systems.
Typical Applications:
Residual charge dissipation for capacitor banks in indoor reactive power compensation switchgear and shunt capacitor bank complete assemblies;
10kV reactive power compensation systems in distribution substations, industrial and mining enterprises, and commercial buildings;
Voltage monitoring and overvoltage/undervoltage protection signal acquisition for capacitor banks;
Indoor oil-free distribution environments as a replacement for oil-immersed discharge coils, eliminating fire hazards.
Functional Purpose: Rapidly dissipates residual charge from shunt capacitor banks following de-energization to ensure safety during maintenance and operation. Simultaneously provides voltage monitoring signals to enable protection and control of reactive power compensation devices, improving the power factor and power supply quality of the electrical system.
Operating Conditions
Normal Operating Conditions
Altitude: ≤2000m
Ambient Temperature: -30°C to +70°C, without severe temperature fluctuations
Relative Humidity: ≤95% (non-condensing)
Environmental Conditions: Free from corrosive gases, flammable/explosive media, severe vibration and shock, and significant dust or salt fog
Installation Method: Indoor post-type mounting; avoid direct sunlight, rain, and condensation
Special Operating Conditions (Custom Order Required)
Altitude exceeding 2000m;
Ambient temperature outside the -30°C to +70°C range;
Severe pollution, salt fog, or chemical corrosion environments;
High vibration or high shock duty conditions;
Non-standard secondary voltage, discharge time, or mounting dimension requirements.
Installation and Maintenance
Installation Requirements
Pre-Installation Inspection: Inspect the discharge coil for external damage — the cast body must be free of cracks, voids, and physical damage; terminal markings must be legible and all accessories present. Verify that the model, specifications, voltage ratio, and discharge parameters conform to the design requirements.
Mechanical Mounting: Position the discharge coil at the designated mounting location within the reactive power compensation switchgear. Secure with bolts through the base mounting holes, ensuring the installation is firm and free of looseness or misalignment. The mounting surface must be level to prevent uneven stress loading.
High-Voltage Side Wiring: Connect the high-voltage terminals in accordance with the design drawings, ensuring tight connections with good electrical contact. Maintain adequate clearance between high-voltage leads and grounded parts to prevent flashover.
Low-Voltage Side Wiring: Connect the low-voltage terminals according to their labels, with separate wiring for voltage monitoring and protection circuits. Ensure correct wiring, and reliably earth the low-voltage circuit to prevent overvoltage generation.
Insulation Testing: Upon completion of installation, measure the insulation resistance of the discharge coil (HV to LV and earth, LV to earth) to confirm insulation performance meets requirements. Verify the discharge circuit wiring is correct and free of open-circuit or short-circuit conditions.
Maintenance Guidelines
Periodically inspect the external condition of the discharge coil: the cast body must be free of cracks, damage, and discharge marks; high-voltage terminals must show no looseness or oxidation; shed surfaces must be free of pollution accumulation.
Periodically inspect high-voltage and low-voltage connections for tightness, absence of thermal discoloration, reliable earthing of the low-voltage circuit, and no risk of open-circuit or short-circuit conditions.
Periodically test insulation resistance and voltage ratio to verify device performance meets requirements, and confirm that the discharge function is operating normally.
Clean dust and contamination from the discharge coil surface; prevent oil and corrosive substances from adhering to the device; maintain a dry and clean condition.
If abnormalities such as cracking, discharge, overheating, or out-of-tolerance voltage ratio are detected, de-energize the equipment immediately for inspection and replace the unit if necessary. Operation with known defects is strictly prohibited.
Safety Precautions
The high-voltage side of the discharge coil must never be operated open-circuit. The low-voltage circuit must be reliably earthed to prevent overvoltage generation that could endanger equipment and personnel.
During installation, avoid impact or collision with the cast body and high-voltage terminal sheds to prevent epoxy resin cracking and insulation damage, which would impair the device’s insulation performance and anti-pollution flashover capability.
High-voltage side wiring must use dedicated insulated leads, maintaining adequate clearance from earthed parts and other live parts to prevent phase-to-phase or phase-to-earth flashover.
Equipment earthing must be reliable; the base earthing terminal must be securely bonded to the switchgear earthing busbar to ensure proper equipment earthing.
During storage, keep the device in a dry, well-ventilated, and cool environment. Avoid direct sunlight, high temperatures, moisture, and mechanical compression to prevent aging and deformation of the cast body.
Equipment installation, commissioning, and maintenance must be performed by qualified electrical personnel in strict accordance with electrical safety operating procedures.
Standard Supply Configuration
| No. | Item | Purpose |
| 1 | JDZ-10 Semi-Enclosed Dry-Type Discharge Coil Body | Core device for capacitor bank discharge and voltage monitoring |
| 2 | Mounting Bolts and Washers | For mechanical fixing of the discharge coil |
| 3 | Low-Voltage Terminal Cover | Protects low-voltage wiring terminals; prevents miswiring and short circuits |
| 4 | Product Manual | Installation, operation, and maintenance reference document, including discharge circuit wiring instructions |
| 5 | Product Certificate of Conformity and Factory Test Report | Product quality and performance documentation, including discharge time test data |
Applicable Standards and Certifications
The product complies with GB/T 11024 Shunt Capacitors for AC Power Systems Having a Rated Voltage Above 1kV, DL/T 653 Technical Requirements for Ordering Discharge Coils for Shunt Capacitors, GB 1094.6 Power Transformers — Part 6: Reactors, and other national standards. The product has passed type testing and its performance meets the operational requirements of 10kV reactive power compensation systems.
Appendix: Product Outline Drawing
