人为接地开盖断电的重大隐患分析及解决方案

Analysis on Serious Hidden Dangers and Solution of Cover Open Power off When Artificial Grounding

在供电127~1140 V系统中,人为接地实现开盖断电已存在于我国部分矿用开关中,但在开盖断电过渡过程及动作失灵状态下,会产生接地过电压;在2台以上开关同时开盖时,会产生大于30 mA安全电流的接地过电流;还有一些开关是在松动盖板紧固螺栓后（即失爆后）才断电,这些都是重大隐患。因此提出将矿用本安型开盖传感器锁定在电气设备盖板紧固螺栓上,其接点与安全保护监控系统（回路）连接,将要开盖时,先开锁,再断电,然后才能松动紧固螺栓,打开盖板,该方法可使国内外所有在用井下电气设备（包括开关、电机及电缆连接器等）实现超前开盖断电,从而避免上述隐患。

In the 127~1 140 V power supply system,the artificial grounding to have the cover open power shut off has been applied to the major mine switches in China.An overvoltage grounding would be caused during the cover open power off transition process and under the condition of the action sensitivity lost.When over two sets of the switches to be opened at the same time,there would be a grounding overvoltage over 30 mA safe current occurred.Some switches would be shut off only when the fastened bolt of the cover released（the flameproof function lost）.Those all would be the important dangers.Therefore it proposed that the mine intrinsic safe cover sensor should be locked on the cover fastened bolt of the electric equipment and the connection point of the sensor should be linked with mine safety protection monitoring and control system（return circuit）.Before the cover to be opened,the lock should be firstly opened,the power would be secondly shut off,then the fastened bolt could be released and the cover could be opened.This method could be applied to all kind home and abroad electric equipment in the underground mine to have the advance cover open power off in order to eliminate above dangers.