Core Analysis Of Electrical Safety Compliance For Constant Voltage Transformers

In industrial power systems, the stability of equipment operation directly depends on its compliance with international and domestic safety standards. According to GB/T 19212.13-2019 and IEC 61558-2-12:2024 standards, the design and manufacture of 3 phase constant voltage transformer must strictly comply with specific electrical insulation and protection specifications. In stationary or mobile applications, these power supply units must meet comprehensive testing requirements, from electrical clearances to temperature rise limits, to maintain voltage stability at the grid load end.

Insulation Structure and Withstand Voltage Rating Definitions

The standard specifies clear insulation levels for isolation between the input and output windings. For Class I constant voltage transformers not intended for connection to the grid, a basic insulation plus protective shielding scheme can be used between the input and output windings to replace double insulation or reinforced insulation, but specific creepage distance parameters must be met. If the no-load output voltage does not exceed AC 50V or ripple-free DC 120V, it falls under the category of extra-low voltage; otherwise, higher-level insulation protection measures must be implemented. During manufacturing, rigorous breakdown voltage testing is required for both oil-immersed and dry-type cores. The minimum breakdown voltage during initial charging must meet specific kilovolt standards to prevent dielectric failure.

Grounding Protection and Overload Fuses

Shell grounding and circuit protection are the last line of defense against electric shock. All accessible metal parts of all Class I constant voltage transformers must be reliably grounded via a dedicated yellow-green bicolor wire, forming a low-impedance fault current loop. For circuit protection, appropriate in-line fuses or circuit breakers must be installed, especially when the output voltage reaches 650 volts, requiring the use of a residual current device (RCCD). Professional constant voltage transformer for home suppliers integrate overheat protection components during the design phase, automatically cutting off the input source when the internal coil temperature exceeds the insulation class limit, preventing the spread of fire risk.