The overhead cranes in steel companies carry sensitive and heavy loads on melting furnaces. The speed and accuracy of these cranes in proper load carrying will increase the quality and the effective volume of production. Accordingly, Variable Frequency Drive (VFD) technology is used in the power transfer mechanism of these cranes. The drives are capable of providing optimal torque and speed for the system, provided that all the control parameters of a drive are customized to optimize the performance of the system.
Accurate tuning of VFD parameters requires experience as well as extensive knowledge in designing extremo software and model identification. In this way, the engineers of this company, based on expertise teamwork, succeeded to develop a process that is able to provide the most accurate settings for PID control blocks by mathematically modeling of control parameters of a crane. With this setting, the operator’s error due to the operation of master switch is eliminated and any operator can move the load without swing and with the maximum speed.
The advantages of using this system are as follows:
· Crane performance is much softer and less stressful
· Load swing is considerably reduced
· The speed of the operator’s performance greatly increases during a shift
· Voltage and current diagrams have a lower peak and therefore energy losses are reduced
· The start and step operation of the motors are reduced, so the stress and mechanical loss of the gearbox and brake systems are reduced.
· With precise frequency adjustments, the amplitude of the disturbing harmonics of the voltage and current is greatly reduced, leading to extended life of electrical equipments such as motors.
· Handling the master switch in the control room is much less
· All drive capabilities are optimally utilized
· Energy consumption are considerably reduced
1. Mobarakeh Steel Company
2. Esfahan Steel Company