There are two kinds of controls that you can use in cranes and hoists. These two controls are the Variable frequency controls and the 2-speed controls. While comparing the 2-speed controls with the Variable frequency drives, i.e., VFD control for your cranes and hoists, you need to consider various factors. These factors can relate to speed adjustments, load control to extension and efficiency of the hoists life. This article lets us see the benefits of two-speed controls over the benefits of Variable frequency drives control.
Based on certain aspects, let us see how 2-speed controls and Variable frequency drive controls react. Some of the aspects can help one compare and contrast the difference between two-speed controls and the variable frequency drive controls.
In case of greater speed adjustments
- 2-speed controls: One can adjust the speed in 2-speed control. These two levels of speeds are, however, provided by the motor manufacturer. One would not have the ability to adjust it.
- Variable frequency drive controls: However, the variable frequency drive controls allow the user to choose from multiple speed settings. It, however, opens up the scope of customization. Therefore you can choose your speed settings according to your application.
In case of improving load control
- 2-speed controls: When you lock the operator in two-speed control, it becomes difficult to attain precision while positioning a load. Speed control, in this case, becomes very limited, which affects the load swing and the shock loading. However, if you try to jog the hoist in a particular position, the load causes a high rush touch that leads to an increase in heating. It lowers down the lifespan of the hoists.
- Variable frequency drive controls: It ensures smooth operation while slowing down the load gradually. The VFD load control minimizes the load swing due to smoother acceleration while operating in traverse motion.
In the case of brakes
- 2-speed controls: One requires the mechanism of brakes to slow down the hoists. It can be one of the causes of continuous wear and tear. Therefore it leads to a frequent brake replacement or increase in maintenance. Uncontrolled and sudden braking can also cause swaying of excessive load.
- Variable frequency drive controls: The VFD control can systematically slow the crane with the help of dynamic braking. The motor used in this control regenerates the braking energy into the controls, which helps to dissipate heat through resistors. It also gets recycled. However, with the help of variable frequency drive controls, one can only use the brake mechanism for emergency and parking stops. It dramatically extends the life of your machine's brake system.
In case of efficiency
- 2-speed controls: The energy consumed by 2-speed controls, however, gets dictated by speed resistors; while the control system constantly wastes this energy.
- Variable frequency drive controls: In the case of variable frequency drive controls, power consumption takes place only when the motor needs it. It saves a lot of energy compared to any soft starters or contractors.
In case of increased hoist life
- 2-speed controls: While you are incorporating the use of speed controls, you need to increase the process of cleaning and maintenance of the speed registers and breaks, respectively. Due to this, the life of the motor gets shortened.
- Variable frequency drive controls: Some of the Variable frequency device controls provide overcurrent protection and thermal overload for the hoists motor. Due to this, the motor's life gets prolonged, extending the life of windings and insulation. Sometimes the Variable frequency device control utilizes a method of ramp-to-stop braking system minimizing the force. It happens only during emergencies and parking situations.
In the case of regenerative energy
- 2-speed controls: In the case of two-speed control, the regenerative energy is dissipated through the brake shoes or the speed registers. Here all the energy gets converted to heat and finally gets lost.
- Variable frequency drive controls: The lowering or deceleration of the hoist of the crane may result in regenerative energy. This energy is, however, produced by the operation of the motor. The energy, however, gets transformed into heat with the help of a braking resistor. Sometimes it can also be conditioned and later sent back to its previous source, which aids in energy saving. The controller redistributes the portion of energy without wasting it while it gets converted into heat with the help of a braking resistor.
In the case of digital diagnostics
- 2-speed controls: With the provision of 2-speed controls, one would not record or maintain any diagnostic information.
- Variable frequency drive controls: However, with the help of variable frequency drive control, you can opt for digital diagnostics. It, however, helps in troubleshooting and maintaining the machine systems.
Conclusion
Therefore the serious frequency drives control provides numerous benefits when compared to the two-speed control. When you use the variable frequency drive controls throughout the period, you tend to prolong the life of your equipment while saving a lot on energy costs. You can also standardize the motor type you use on your equipment to cut down the total cost of ownership.
Moreover, it becomes important that you use the variable frequency drive controls while replacing the two-speed controls to provide you with more practical benefits.
