DIN EN 50021-2000 electrical apparatus for potentially explosive atmospheres – type of protection “n”; german version en 50021:1998
DIN EN 50021-2000 潜在爆炸性气体环境用电器 n 型防护装置
DIN EN 50021-2000 electrical apparatus for potentially explosive atmospheres – type of protection “n”; german version en 50021:1998
DIN EN 50021-2000 潜在爆炸性气体环境用电器 n 型防护装置