There are 2 ways for mine lifting: perpendicular shaft and incline shaft, mine hoist is the key equipment in the mine production, is called the throat of mine. It is be responsible for lifting the mineral, mullock, equipment, material and operators.
For example, some company’s inclined shaft hoist(model# 3-2), use the traditional speed control mode by rotor winding series resistors. This mode has the following problems:
1) It takes too long time to judge and remedy the faults, because of using many electromagnetic relays. After a long time running, the malfunction rate is high, not only revise the repair costs, but also affect the amount of output.
2) Low degree of automation, big noise when running, improve the room temperature is high, hoist driver is easy to fatigue, great labour intensity.
3) When continuously lift heavy weights with low-speed, resisters heat seriously, often burned out resistor connection, large energy consumption.
4) Speed control by stepless speed regulation, the wire rope and reducer must bear large mechanical shock.
2. Upgrading scheme and system composition
1) Upgrading scheme
Use inverter, PLC, Energy Feedback Unit and touch screen etc to make up an AC speed adjustable system.
2) System composition
Frequency conversion circuits: Knife switch, circuit breaker, inverter, contactor and feedback unit of energy.
Control loop: It is made up of Main PLC, Auxiliary PLC, touch screen, relay auxiliary control and operation station. The Main PLC are Auxiliary PLC are backup for each other. Relay, Main PLC, Auxiliary PLC are mounted in one cabinet, touch screen is mounted on the operation station as PC. Encoder is mounted mounted together with the motor and roll.
3. Operating principle
1) System has 4 functions as below.
Stop: In this state, the system stopped working, all operations are not carried out, in winch brake braking state.
Manual operation: When the system satisfy the premise of safe operation, according to the parameters of the meter and touch screen display, to operate normal manual winch for up or down operations by the master controller.
Automatic operation: Push up or down buttons to automate the entire process of upping and downing. When run in halfway, can be stopped by the stop button for manual intervention. And restart by pushing the buttons.
Let slip: When Serious failures is happened in the system can’t be working properly to run up or down, should convert the function switch to this location, then make the hoister run in the specified place by master controller.
This system has the following characteristics:
①High precision for speed adjustment, wide speed range, the tolerance is under 0.05%.
②Double – wire Protection: Using A hardware circuit and 2 Software Safety circuits redundant to each other, make the system more secure and reliable.
③Double – wire control: In normal working, due to use the double PLC system to monitor each other and mutual redundancy, when one of the PLC system fails, another PLC system can still carry out emergency drive to improve the operation reliability of winch system.
2) Protection and interlock function:
① When safety braking, coupled with hydraulic relief valve to achieve first or second class braking of hoist and make inverter in the regenerative braking state.
② In any case, driver operate the hoister to run only after receiving the driving signal.
③ There is a corresponding fault message displayed on the touch screen if meet any faults, lights the corresponding information lamp as well. Inform the driver stop this work, when faults remove for the next upgrade allows the driver continue work.