The difference between the soft start of F77DRE160M4 deceleration motor and traditional reduced pressure start. Due to the high constant current of the motor during startup, some protective measures are usually taken, such as reducing pressure starting or soft starting. So what is the difference between these two types of startup?WPEKS60-100,WPEKS70-120,WPEKS80-135,WPEKS100-155,WPEKS120-175
The rotor current at the moment of starting a three-phase asynchronous motor can usually reach 5-8 times the rated state. As the rotor current is induced from the stator winding, the current in the stator winding correspondingly increases to 4-7 times the rated value. Such a large starting current will bring the following adverse consequences: causing fluctuations in the grid voltage (especially when starting large capacity motors). So, what are the differences between soft starting of motors and traditional vacuum starting?
1. No surge current. When starting the motor, the soft starter gradually increases the conduction angle of the thyristor, causing the starting current of the motor to increase linearly from zero to the set value.
2. Constant current start. A soft starter can introduce current closed-loop control to maintain a constant current during the starting process of the motor, ensuring smooth starting.
3. According to the load situation and the characteristics of the power grid relay protection, it can be freely and steplessly adjusted to the appropriate starting current.
The reason why the soft starter is superior to the star triangle starter and the self coupling voltage reducing starter is because it has many functions, intelligence, and can achieve human-machine "dialogue". Through keyboard, computer or manual remote operation, it can not only achieve soft stop, but also have many protective functions. These are all requirements for new humanized devices, so it is highly respected.
The soft start operation has the following characteristics.
A. It can steadily increase the starting voltage of the motor with a constant slope, reduce the starting current, have no impact current on the power grid, and reduce the mechanical impact on the load.
B. The slope of the startup voltage rise is adjustable, ensuring the smoothness of the startup voltage. The startup voltage can be continuously adjusted within the range of (30% to 70%) of the rated voltage according to different loads.
C. The startup time can be set according to different loads.
D. In order to adapt to modern production, reduce the impact on the power grid and mechanical wear, and reduce the maintenance of the starting device, the soft starter also has thyristor short circuit overload protection, phase loss protection, overheating protection, and other protection functions.
Overload protection function - The soft starter adopts a current control loop to track and detect the changes in motor current at any time. By increasing the setting of overload current and inverse time limit control mode, the overload protection function is achieved. When the motor is overloaded, the thyristor is turned off and an alarm signal is issued.
Phase loss protection function - During operation, the soft starter detects changes in three-phase current at any time. Once a current interruption occurs, a phase loss protection response can be made.
Overheat protection function - detects the temperature of the thyristor heat sink through the thermal relay inside the soft starter. Once the temperature of the heat sink exceeds the allowable value, the thyristor is automatically turned off and an alarm signal is issued.
Other protection functions - through the combination of electronic circuits, various other interlocking protections can also be implemented in the system.
