Problems with insufficient control functions
Start and stop problems
Unable to start normally: If the control function cannot meet the power requirements, when starting a high-power load (such as a large motor), it may not provide enough starting current, resulting in the motor being unable to start. For example, if a high-power motor is started directly without using a suitable step-down starting method or soft starter, the power supply line of the control cabinet will produce too much voltage drop, causing the motor end voltage to be too low and unable to start.
Frequent fault shutdown: For loads that are frequently started and stopped, simple control functions may cause frequent fault shutdowns of the equipment. For example, if a reasonable start interval and overload protection function are not set, the frequent starting of the motor in a short period of time will generate excessive starting current, causing control components such as contactors to frequently operate and be damaged, and then the equipment cannot operate normally.
Control problems during operation
Speed regulation is difficult: In scenarios where speed regulation of loads such as motors is required, if the low-voltage control cabinet does not have a speed regulation function or the speed regulation accuracy is not enough, it cannot meet the process requirements. For example, in the energy-saving transformation of fans and water pumps, if the motor speed cannot be accurately controlled, it is difficult to adjust the flow and pressure according to the actual working conditions, and energy-saving effects cannot be achieved.
Fault in forward and reverse switching: For loads that require forward and reverse control, such as electric valves and conveyor belts, mismatching of control functions may cause faults during forward and reverse switching. If reasonable electrical interlocking and time delay are not set, the motor and control components may be damaged due to excessive current at the moment of forward and reverse switching, and safety accidents may also occur, such as the sudden reverse movement of the conveyor belt causing the material to fall.
Failure of complex logic control
Chaotic sequence control: In complex application scenarios such as automated production lines, multiple devices need to start and stop in a specific order. If the control function of the low-voltage control cabinet cannot meet this sequential control requirement, the operation sequence of the equipment will be chaotic. For example, in a coating production line, if the previous painting process has not been completed, the next drying process will be started in advance, which will cause product quality problems.
Lack of interlocking control: The lack of necessary interlocking control functions may cause safety problems. For example, in an elevator control system, interlocking control is required between the car door and the floor door to ensure that the floor door can only be opened when the car stops at the correct floor and the car door is open. If the control function does not match, this interlocking failure may cause the risk of passengers falling into the shaft.
Problem of excess control functions (relative to power demand)
Increased costs
Waste of hardware costs: If a low-voltage control cabinet is equipped with advanced control functions, but the actual power demand is low, it will cause a waste of hardware costs. For example, for a small ventilation device that only needs simple start-stop control, if a high-end low-voltage control cabinet with a complex programmable logic controller (PLC) and multiple communication interfaces is selected, the equipment cost will increase significantly, and these advanced functions will not work in this application scenario.
Increased installation and maintenance costs: Control cabinets with complex control functions usually require more professional installation and maintenance personnel, and their size may be larger, requiring more installation space. In the case of low power demand, these additional installation and maintenance costs and space occupation are unnecessary.
Reduced system stability
Potential failure points caused by complex functions: Too many control functions will increase the complexity of the system, thereby introducing more potential failure points. For example, a control cabinet with a large number of communication interfaces and software programming functions may fail due to software conflicts, communication interference and other problems, which do not exist in a system with simple control functions.
Risk of misoperation caused by excessive control: Complex control functions may increase the risk of misoperation in the case of simple power demand. For example, too many control buttons and parameter setting options may confuse operators, resulting in false starts and false adjustments during operation, affecting the normal operation of the equipment.
