The dotted line box is the control line added after the transformation. The problem arises in the production, there is such a fault phenomenon: after the remote control stop button sB3 of the oil heater is pressed, it does not work, and the oil pump motor cannot be stopped (only one of the four oil heaters can function). In principle, such a failure should not occur. Carefully check that the installation line is not connected correctly and there is no problem with the transmission of the line.
After analysis, when the remote control stop button SB3 is pressed, the coil of the intermediate relay KA is de-energized. At this instant, the contactor KMI has not yet been actuated, its normally open contact has not yet been opened, and the normally closed contact of the intermediate relay KA has been closed. It is precisely because the intermediate relay is preemptively operated than the contactor, so the power of the near-control can not be stopped, and the motor of the oil pump cannot stop. And an oil heater works normally because its intermediate relay has no preemptive action than the contactor. However, as the production operation progresses, it is not clear when the intermediate relay will act preemptively. Therefore, for the reliability and safety of the system, the design line must be changed.
There are many ways to solve the problem. Considering that the oil heater is on the first floor of the workshop, the machine and the control box have been installed. And its remote control button is set on the console of the main control room on the second floor.
Therefore, it was decided to add a pulse encoder with a precision rack along the moving axis on the console. The feed transmission part of the machine is contained in the position closed loop, so the mechanical system error can be eliminated by feedback.
(Finish)
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