PLC Electrical Control Gantry Crane
Application of NA400 PLC Electrical Control in Gantry Crane
Abstract: Aiming at the aging of the related equipment of gantry cranes the operating characteristics of the crane are analyzed, and an advanced control scheme of the crane is presented, which improves the running efficiency and stability of the crane.
First, the status quo and feasibility analysis
Gantry cranes are mainly engaged in coal loading and unloading operations, ship unloading operations rely mainly on bridge crane and door machine equipment. Loading and unloading machinery and equipment status is good or bad, a direct impact on the efficiency of the company unloading operations. With hoisting, opening and closing, the luffing mechanism uses the winding rotor asynchronous motor rotor series resistor speed control, the speed control method of the shortcomings of the resistance heating is serious, leading to rapid rise in ambient temperature, the overall performance Indicators poor, low efficiency; induction motor with collecting ring and brush, requiring regular maintenance. Coupled with a large number of relays, the use of contactors, leading to frequent failures, maintenance of large. The electric brake uses the eddy current electrical machinery to brake, the dynamic performance is bad and the energy consumption is high. The traditional system programmable controller uses the Hitachi eighty’s product, only can handle the simple switch quantity, the scanning time is long, causes the mechanical work efficiency to be low. To this end the decision to carry out a comprehensive upgrading of the device, the drive to upgrade to frequency control, the control upgrade to the now more advanced PLC. Using Nucleon NA series PLC on the door machine application, compared with the original system can bring the following benefits.
1) motor mechanical properties of hard, accurate positioning, can improve the discharge efficiency.
2) smooth operation, since the brake gently, running in Canada, deceleration of the machine to reduce the impact, improve security and extend the life of machinery.
3) Remove the eddy current brake, the electrical braking by the inverter to achieve, reducing energy consumption while also reducing the amount of maintenance.
4) mechanical braking in the motor speed close to zero speed input, so the mechanical brake brake life greatly extended, maintenance costs.
5) The original winding rotor asynchronous motor speed resistor removed; shorted to the collection loop to the winding rotor induction motor as a squirrel cage motor, saving the cost of replacing the motor.
6) a large number of exchanges and contacts to reduce the motor to achieve stepless speed; avoid contactor contacts frequent action and burned and the resulting damage to the motor failure.
7) combined with a powerful PLC and the inverter’s own protection, detection, fault alarm and other functions, can greatly improve the stability of electronic control system.
8) the original PLC costly, the use of NucleonNA400PLC reasonable price, spare parts sufficient maintenance easy to reduce the equipment risk.