Use of frequency converters and ordinary motors
Thread Content
Currently, there is a single-screw pump equipped with a 1.5KW–6 ordinary motor and an inverter; each time it is started, the pump’s coupling has to be turned manually. Is this normal? Additionally, the manufacturer explains that inverters are best used with variable-frequency motors; using ordinary motors with them is not reasonable. It affects the service life of the motor. . .
Indeed, a change in frequency can affect the lifespan of ordinary motors. In cases where the frequency changes significantly, it is better to use an inverter motor.
It seems that there’s no need to turn the machine by hand after frequency conversion
Now, every time it is started, the coupling needs to be turned by hand – is this normal?
According to the equipment’s specifications, this is the case; however, since the frequency converter enables a low-speed, gradual start-up, it should not cause any damage to the equipment. Of course, turning the shaft by hand still has its advantages. If it is a viscous material, or if the equipment is not used for a long time, problems may arise
Starting a screw pump requires significant torque; it can be started at a high frequency and then the frequency reduced to the desired level. A lower frequency has an impact on the motor’s cooling, as the fan rotates more slowly and thus generates less airflow. However, as long as the frequency is not below 25 Hz, the risk of the motor overheating is low. If it is too low, the shaft at the end of the fan blade can be shortened, a cover can be installed, and after attaching the fan, it becomes a variable-frequency motor.
1. If the pump is not in use for an extended period of time, or if it is uncertain whether there are any residues in the pump’s medium that could cause it to stick, it is necessary to rotate the pump before starting it up. This is done to protect the pump, as well as to prevent the motor from being overloaded due to sticking. 2. The operating frequency of industrial frequency motors is limited, ranging from 75% to 100%. When the frequency is low, the speed of the cooling fan also decreases, resulting in insufficient cooling. This leads to severe overheating of the motor, and the internal wire windings are prone to aging. The cooling fan of the variable-frequency motor is powered independently, so theoretically it ranges from 0 to 100%.
A regular motor, equipped with a reducer – how expensive are variable-frequency motors?
A separate fan can be connected to facilitate heat dissipation
What was said on floors 7 and 8 makes a lot of sense; I support the use of variable-frequency motors to adjust the speed and thereby control the flow rate. However, variable-frequency drives have their own disadvantages. The original poster might consider using manual stepless speed control motors, which could be more suitable