ISO 5826:2014给出了适用于电阻焊设备中使用的IEC 61140 I或II级保护变压器的规范:交流焊接用单相变压器，通常在50 Hz或60 Hz下运行；单相变压器，带有直流焊接用连接整流器，通常在50 Hz或60 Hz下运行；单相逆变变压器，带有连接整流器，用于直流焊接，通常在400 Hz至2 kHz的频率下运行；三相变压器，带有连接整流器，用于直流焊接，通常在50 Hz或60 Hz下运行。

ISO 5826:2014 gives specifications applicable to transformers of IEC 61140 protection class I or II of the following types for use in resistance welding equipment: single-phase transformers for a.c. welding, typically operating at 50 Hz or 60 Hz; single-phase transformers with connected rectifier for d.c. welding, typically operating at 50 Hz or 60 Hz; single-phase inverter transformers with connected rectifier for d.c. welding, typically operating at 400 Hz to 2 kHz; three-phase transformers with connected rectifier for d.c. welding, typically operating at 50 Hz or 60 Hz.