Will the stopped equipment start automatically?

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In the 1980s, a serious acid burn accident occurred in a certain unit. Personal analysis of the cause of the accident is inconclusive. I will share it here for everyone to discuss. Please express your opinion. 1. The incident happened on June 1, 198X. During the process of repairing and installing the outlet pipe of the dry acid pump, the maintenance team of the sulfuric acid workshop suddenly started the acid pump, and a large amount of sulfuric acid spurted out from the outlet of the acid pump, causing a mass injury accident in which 7 people involved in the maintenance were injured. 2. Investigation results at that time 1. It is suspected that someone intentionally (or unintentionally) started the equipment switch, causing the acid pump to start. (However, this reason was eventually denied because there was no real evidence, but it can exist as one of the unsolved reasons. ) 2 It is suspected that due to water intrusion on the electrical control board and the fact that the power supply was not completely disconnected, the electrical control circuit suddenly closed, causing the acid pump to start automatically. This reason was considered the final analysis result. There were indeed some problems with electrical control at that time.: (1) In the 1980s, the control panels used were wooden boards installed on the wall. If you were not careful, water would splash on the switch board. ； (2) The control circuit uses a conventional contactor control circuit, with only overcurrent thermal relay protection. ； (3) After shutdown, the power supply to the switch board is indeed not disconnected ； (4) After the shutdown, the maintenance personnel did not recheck whether the power of the three-phase line was really completely disconnected, but the acid pump did stop running. ； (5) After shutdown, the "No closing" sign was not hung. question: Please express your opinion. Is the acid pump really caused by the automatic activation of the circuit? How likely is it to start automatically, and can it deny the possibility of manual closing? This post was last edited by safe30 on 2009-3-10 01:26 ]