Sequenced mine shaft ventilation system - employs programmed switching of fans off and on to protect plastics ducts

摘要

The mine shaft ventilation system using plastics ducts employs a system for starting up and stopping the motor driving the fan in a sequence which avoids excessive impacts on the walls of the ducts so as to avoid damage. A relay control system is used in which each motor is operated in pulses, with switched on pulses lasting different periods of time, alternating with switched off pulses, also lasting different periods of time. These are controlled to suit the required conditions, and the fans are operated in sequence, in accordance with a protection system.