IEC 60137 pdf – Insulated bushings for alternating voltages above 1 000 V 1 scope This International Standard specifies the characteristics and tests for insulated bushings. This standard is applicable to bushings, as defined in Clause 3, intended for use in electricalapparatus，machinery,transformers,switchgear and installations for three-phase alternatingcurrent systems，having highest voltage for equipment above 1 000 V and power frequenciesof 15...