Sarah Jenkins: Procedures for Installing CL01-12 High Voltage Diodes in Oil and SF6 Gas

Introduction: During high-voltage equipment integration and development, design engineers select an insulation medium and installation configuration prior to placing a diode into an oil-immersed tank, an SF6 chamber, a potted assembly, or an air-cooled enclosure.

Those integrating oil-immersed or gas-insulated high-voltage equipment must align the diode with the insulation medium, heat path, and electrode configuration prior to installation. The CL01-12, a 12KV, 350mA low-frequency high-voltage diode offering 30A surge capability, is advised for use in insulating oil and insulating gases and accommodates secondary packaging. The surrounding medium also influences the installation: oil, SF6 gas, potting compounds, and exposed air each affect the electric field, heat transfer, and terminal setup. The installation approach should take these conditions into account along with the elements that require verification before assembly.

Why Insulating Oil Changes the Installation Conditions for Axial Leaded Diodes

Insulating oil serves more than a filler function. It enhances dielectric strength around the diode body and leads while drawing heat away from the epoxy surface. For an axial leaded high-voltage diode, this alters both the electrical and mechanical configuration. Within oil, the creepage path along the lead no longer relies solely on air. When the oil remains clean, dry, and properly maintained, it occupies gaps and lowers the likelihood of surface flashover. Practices for mineral-oil-immersed equipment and dielectric studies both indicate that oil quality and temperature significantly influence breakdown behavior. CL01-12 is recommended for insulating oil applications. Its high thermal conductivity epoxy molding facilitates heat transfer from the chip to the oil, and its specialized high-temperature-resistant chip protective glue enables operation across the -40°C to +125°C range. The oil installation must specify how the diode is positioned in the tank. The leads should be supported so that vibration or oil flow does not strain the connections. Adequate clearance between the diode body and grounded metal must be maintained. Compatibility of the oil with the epoxy and any potting materials used around the assembly should be verified. A well-planned oil installation leverages the medium both as insulation and as a thermal pathway, which is why oil-immersed designs can operate at lower temperatures than the same diode in air.

What SF6 Gas and Secondary Packaging Require from a High Voltage Diode

SF6 gas and secondary packaging introduce distinct requirements. SF6 serves as a robust dielectric, yet its insulating effectiveness relies on field management and gas purity. Even a minor sharp edge or loose particle can generate a localized high-field zone. Secondary packaging—for example, potting or encapsulation—introduces an additional layer surrounding the diode. While this layer can shield the device, it also modifies the thermal pathway. CL01-12 is recommended for insulating gases and supports secondary packaging; therefore, the gas chamber and encapsulation must be designed with the diode in mind.

Gas chamber field control: Ensure the diode body and electrodes are smooth and adequately spaced. Avoid sharp edges on adjacent metal since SF6 insulation depends on a uniform field. Adhere to the gas compartment's clearance guidelines and verify the final gap around the axial leads prior to assembly.
Secondary packaging material: Select a potting compound that meets the dielectric and thermal requirements of the module. Common choices include silicone, urethane, acrylic, and epoxy, each behaving differently as potting materials. Pick a compound that cures without causing cracks in the diode body or putting strain on the leads.
Thermal path through the package: While the high thermal conductivity epoxy molding of CL01-12 assists heat in escaping the chip, the outer potting material governs the subsequent stage. A thick, low-conductivity layer retains heat. The package should be designed so that heat can transfer to a metal wall, heat sink, or oil or gas volume.
Terminal and clearance details: Axial leads require support and a defined connection approach. If quick connect terminals are employed, verify the terminal specification. Prior to installation, confirm the secondary packaging material, clearance, and terminal specification with the diode supplier.

These requirements are interdependent. Even a gas chamber with proper clearances may fail if the potting compound retains heat, and an effective thermal pathway cannot offset a sharp electrode that disrupts the field. The objective is an installation strategy that addresses the entire assembly rather than a single component selection.

How to Install CL01-12 When the Application Uses Exposed Air

Exposed air represents a challenging installation medium for an axial leaded high-voltage diode. In open air, CL01-12 may experience discharge and has limited heat dissipation. Its compact body size—beneficial for space-constrained equipment—also concentrates the electric field. Using insulating electrodes at both ends is strongly recommended. These electrodes smooth the field and shift the discharge point away from the diode body. Without such electrodes, corona and surface tracking can reduce service life or lead to failure. A practical air installation begins with distance and support. The diode should be mounted so that leads are short and mechanically supported. Clearance and creepage distance to adjacent grounded metal should be increased. Sharp screws, wire ends, and chassis edges must be kept away from the diode body. If forced air is available, it can be directed across the epoxy body, but air cooling alone should not be relied upon for high continuous current. Where the design permits, the diode should be moved into insulating oil, SF6 gas, or a secondary package. If air exposure is unavoidable, insulating electrodes should be used and the final clearance within the enclosure verified. The 12KV, 350mA rating and 30A surge capability define the diode’s electrical performance; the installation must still account for the medium. The same diode that operates cool in oil can overheat in still air, and a layout that functions inside a sealed gas chamber may discharge at a sharp edge in open air. The air installation should be approached as a field-control problem, not merely a mounting task.

Conclusion

The appropriate installation plan for CL01-12 depends on the medium surrounding the diode. Insulating oil offers dielectric strength and heat transfer. SF6 gas demands clean field control and proper clearances. Secondary packaging adds protection but alters the thermal pathway. Exposed air requires insulating electrodes and generous spacing, as discharge and heat are genuine limitations. Hvdiode manufactures high-voltage diodes and supplies the CL01-12, an axial leaded 12KV, 350mA diode featuring high thermal conductivity epoxy molding and a specialized high-temperature-resistant chip protective glue. To move from concept to production, send your medium, clearance, terminal, and packaging details to the manufacturer’s team and request a sample, quote, or datasheet. Confirm secondary packaging materials, clearances, and terminal specifications prior to installation.

FAQ

Q：Can CL01-12 be used in insulating oil or SF6 gas without additional insulation?

A：CL01-12 is recommended for insulating oil and insulating gases like SF6. Its high thermal conductivity epoxy molding and special high-temperature-resistant chip protective glue facilitate such usage. The need for additional insulation is determined by the system design, clearances, and electrode arrangement. Adhere to the equipment’s mounting guidelines and verify the final clearance with the manufacturer or supplier.

Q：What installation changes are needed when an axial leaded high voltage diode is used in exposed air?

A：In open air, CL01-12 may discharge and heat dissipation is restricted, making insulating electrodes strongly recommended at both ends. Increase clearance and creepage distance, support the axial leads, and keep sharp grounded metal away from the diode body. Where the design permits, relocate the diode into insulating oil, SF6 gas, or secondary packaging. For an unavoidable air installation, prioritize field control planning and verify the final clearance within the enclosure.

Q：How does secondary packaging affect heat dissipation for a high voltage diode?

A：Secondary packaging introduces an insulating layer around the diode, which can either aid or impede heat flow. CL01-12 employs high thermal conductivity epoxy molding and a special high-temperature-resistant chip protective glue to transfer heat from the chip to the surface. The outer potting material and its thickness dictate how effectively heat dissipates. Verify the packaging material and thermal pathway with the manufacturer or supplier prior to installation.