To understand the current status of major occupational hazards in 750 kV extra high voltage (EHV) substations.

In July 2019, through investigating and detecting the sulfur hexafluoride, power frequency electric field and noise occupational hazards of 750 kV EHV substations in substation 1, substation 2, substation 3, substation 4, substation 5, substation 6 and substation 7, the exposure intensity of the sulfur hexafluoride, power frequency electric field and noise intensity that the operators are exposed to during the inspection process were analyzed.

The qualified rate of 358 sulfur hexafluoride test results was 100.0% of the seven 750 kV EHV substations. The qualified rate of 8 h time-weighted average of the power frequency electric field of those 750 kV EHV substations contacted by operators was 100.0%. Among the 847 power frequency electric field detection points, the exceeding standard rate of power frequency electric field was 64.3%, and the differences in the power frequency electric field detection exceeding standard rates of different substations and inspection areas were statistically significant (χ²=87.52, 50.86, P<0.01) . The highest exceeding standard rate of power frequency electric field was the circuit breaker inspection area (94.4%, 34/36) . The noise intensity test results of the seven EHV substations were 41.1-79.7 dB (A) , and the qualified rate was 100.0%.

The sulfur hexafluoride, power frequency electric field and noise that the operators contacted in 750 kV EHV substations meet the requirements of occupational exposure limits. The inspection areas of main transformers, capacitors, reactors, bus bars and switches have high power frequency electric field radiation, should be select equipment iand give priority to robot inspection, and reasonably adjust the inspection time to reduce the intensity level of substation operators' exposure to power frequency electric field.

Occupational exposure; Sulfur hexafluoride; Power frequency electric field; Noise