Graduation thesis on PLC electrical control of double constant pressure tower-less water supply

Chapter 1: design requirements

1. Receive and register all command signals of elevators outside the floor, register and output registration signals.

Second, according to the earliest registered signal, automatically judge whether the elevator is going up or down. This logical judgment is called elevator direction. The direction of the elevator can be divided into two types according to the nature of the first registered letter. One is instruction orientation, and the instruction is to compare the destination indicated by the instruction with the current elevator position and draw the conclusion of "ascending" or "descending". For example, the elevator is on the second floor, and the instructions go down on the first floor; If the order is the fourth floor, then go up. The second is the call direction, which is based on the comparison between the source position of the call signal and the current elevator position, and draws the conclusion of "rising" or "falling". For example, the elevator is on the second floor, and passengers on the third floor want to get off and press AX3. At this time, the elevator will run to the third floor to pick up passengers, so the elevator will go up.

3. When the elevator receives multiple signals, the first signal is used for orientation and the same signal is used for orientation. Perform the same signal first, and then reverse the direction after performing all tasks in one direction. For example, on the third floor of the elevator, the second floor command signal, the fourth floor command signal and the first floor command signal are sequentially input. If you queue with signals, the elevator goes down to the second floor-up to the fourth floor-down to the first floor. In the same direction, the elevator goes down to the second floor-up to the fourth floor. Obviously, the second method is short and efficient.

Fourth, it has the same parking function. For example, the elevator is on the first floor, and the instruction is on the fourth floor, so go up, and there is call information on the third floor. If the call signal is the call direction (K5), when the elevator reaches the third floor, it will stop carrying passengers. If the call signal is call down (K4), you can't stop, but go to the fourth floor first and then return to the third floor to stop.

Five, a direction of the task needs to reverse, according to the principle of reversing the farthest station. For example, the elevator goes to the first floor according to the instructions on the second floor. At this point, the third and fourth floors are calling the elevator to send out downlink signals. The elevator stops at the second floor, and then continues to go up after getting off. If you stop at the third floor and change direction, you can't take care of the requirements of the fourth floor. If you stop on the fourth floor and change direction, you can park in the right direction on the third floor.

6. Use MCGS configuration software to monitor the operation of the system. Realize the monitoring function.

Chapter 2: The basic structure of AC elevator.

The electrical system of the elevator includes two parts: the electrical drive system and the electrical control system. The electric drive system has various AC and DC speed regulation systems. At present, the electrical control system has gradually adopted programmable controllers and microcomputer control systems with higher reliability and universality, but there are still a large number of elevators using relay-contactor control systems.

This graduation project adopts XPM four-story four-station passenger and freight elevator, AC pole-changing speed regulation and relay contactor control. In XPM model, X stands for floor selection button control, P stands for automatic floor selection, and M stands for automatic door.

The basic structure of elevator can be divided into four parts according to its position: machine room, shaft, car and hall door.

One: Computer room part

The machine room is located on the top floor, above the hoistway, and includes the traction machine, control panel and speed limiter.

(1): traction machine

Traction machine is the driving mechanism of elevator, including traction motor, electromagnetic brake reducer and YTD series two-speed motor for elevator. The reducer adopts worm gear to slow down. The traction sheave is V-shaped or the counterweight is suspended on the sheave. When the car rises, the counterweight drops; Otherwise, when the car descends, the counterweight rises, and the car and counterweight slide in their respective guide rails in the hoistway.

(2): Control panel

The control panel is equipped with most electrical appliances of the elevator electrical control system, including fuses, contactors, various relays, transformers, rectifiers and various resistance-capacitance elements.

(3): Speed limiter

The speed limiter is a special safety protection device for elevators. Usually, centrifugal block-throwing rope speed limiter is used.

Two: the shaft part

The hoistway is the passage through which the elevator car moves vertically. The hoistway is equipped with car, counterweight guide rail, buffer and various electrical appliances for control and protection. —— Limit switches, floor sensors, flat magnetic isolation plates, etc. 、

Three: the car part

The car part of the elevator includes car body, safety tongs, car door automatic opening and closing device, flat floor and floor signal device, and unmanned control panel and indicator light of the car.

(1): body

A car is a device used by an elevator to transport passengers or goods. Comprises a vehicle frame, a vehicle body and a vehicle door.

(2): Automatic switching device

Door switch and motor door switch control device The car door is driven by a motor and can be opened and closed automatically. DC motor is used for door opening and closing.

(3) Flat floor and floor signal sensor device,

From the point of view of electric traction automatic control, the elevator is an electrical equipment that runs vertically. The device that controls according to the running position and sends floor and floor position signals to the control circuit is a permanent magnet sensor.

The flat inductor is generally a permanent magnet inductor, which has the same structure as the variable speed inductor and consists of a reed switch and a permanent magnet. The reed switch is a vacuum tube with contacts, and its moving contact 2 is made of a magnetic spring. Contact 1-2 is equivalent to a set of moving contacts, and contact 2-3 is equivalent to a set of moving contacts. Because the reed switch is installed next to the permanent magnet, the reed moves under the action of magnetic field, and its moving contact 1-2 is disconnected, and the moving contact 2-3 is disconnected. Using permanent magnet inductor as the main command device of position control has the advantages of quick and reliable action and no disadvantage of easy mechanical wear of travel switch.

The flat panel sensor that sends out the flat panel signal is installed on the vehicle, the flat panel sensor is installed on it, and the door opening sensor is installed in the middle. Three sensors move up and down with the car, and the plane magnetic isolation plate is fixed in the hoistway. When the car reaches the floor stop position, the flat magnetic isolation plate is inserted between the three sensors, so that the car bottom plate is just flush with the floor. The principle of floor signal sensor is the same as this, but the difference is that the magnetic stop plate is installed at the top of the car and moves with the car, while the floor sensor is fixed in the hoistway (one for each floor).

(4): In-vehicle control panel and indicator light.

The car is equipped with a control panel, which is equipped with floor selection buttons and various control buttons. There is an indicator light on the car door to indicate the number of floors where the car is located.

Four: the hall door part

The hall door part mainly includes the hall door, the call button and indicator light outside the hall door.

Send all QQ after scoring: 87041989.