... high building,airport,station,wharf,enterprise,tunnel,etc.It is mainly used in power supply occasions of AC 50-60HZ and voltage ... high building, airport, station, wharf, enterprise, tunnel, etc. It is mainly used in power supply occasions of AC 50~60Hz and voltage ... .Electric strength: no breakdown or flashover phenomenon under power frequency sine voltage of 2000V for 1min 10.Overload capability: for ...