●Comparison between adjustable speed magnetic coupling and frequency conversion device
1) Because it is a purely mechanical component, its service life, stability and reliability are higher than those of frequency conversion devices.
2) The frequency conversion device will generate some harmonics with multiples of 50/60 Hz. These harmonics will distort the voltage waveform. The voltage waveform distortion will cause the surrounding sensitive electronic equipment to fail to work. At the same time, the harmonic current will reduce the total power factor of the system by 15. % or more, thus affecting the power-saving effect. When the system equipped with a frequency conversion device needs to run at full power, it will not only save electricity but consume electricity; but the system equipped with a speed-adjustable permanent magnet eddy current transmission device does not have the above-mentioned problems. Under the same working conditions In comparison, the speed-regulating permanent magnet eddy current transmission device saves about 10% more electricity than the frequency conversion device.
3) In the load requirement, under the condition of low-speed operation (less than 30% of the rated speed), the frequency conversion device cannot work, and even if it works, there is no speed regulation accuracy. However, the speed-regulating permanent magnet eddy current transmission device has no such restrictions. It can safely make the motor run normally in a low-speed environment and perform stepless speed regulation on it.
4) Because the frequency conversion device is an electrical component, as we all know, electrical components are replaced very quickly. As time goes by, it may be difficult or impossible to find accessories for some fragile parts such as circuit boards. At the same time, the frequency conversion device has relatively strict requirements for the working environment. Therefore, the adaptability and almost maintenance-free performance of the speed-regulating permanent magnet eddy current drive device in the harsh working environment are not available in the frequency conversion device.
5) In the current frequency conversion device system, most users do not configure frequency conversion motors in order to reduce equipment purchase costs, but continue to use the original three-phase asynchronous motor; in actual work, the frequency conversion device reduces the speed of the motor to make the three phases The phase asynchronous motor runs away from the rated speed, and the relationship between the speed, torque and power consumption of this kind of motor is nonlinear, so the operating efficiency of the motor is greatly reduced; in addition, the frequency conversion device is through 10,000 to 20,000 instantaneous The voltage pulses raised to the highest voltage drive the motor. Such frequent voltage mutations lead to aging of the motor winding insulation and ultimately to winding failure. The variable speed permanent magnet eddy current transmission does not have these problems.
6) When the voltage fluctuates, the frequency conversion device cannot work, and the speed-regulating permanent magnet eddy current transmission device is not affected. The frequency conversion device is a sensitive electronic device, and unstable voltage will cause damage to the frequency conversion device. Compared with direct-connected motors, frequency conversion devices have higher requirements on the quality of the power supply. The speed-regulating permanent magnet eddy current transmission device can realize the speed regulation function like the frequency conversion device, but it does not have any requirements for the quality of the power supply.
7) "groove" phenomenon on the bearing. All variable frequency devices cause current to flow through the motor bearings. As with arc welding, ripples are formed at the contact surface between the ball and the raceway. Bearings damaged by electric current generate noise and vibrations because the raceways are no longer smooth. When the motor is running under load, the shaft current gradually increases, and if the bearing is under load, then the bearing will have more damage. Speed-regulating permanent magnet eddy current transmission does not have these problems.
8) On a 50 or 60 Hz power distribution system, the impedance of the motor windings and cables is low. The voltage pulse output by the frequency conversion device contains high-frequency harmonics that can reach megahertz. Such high frequency harmonics are reflected between the winding and the cable changing the impedance. The reflected harmonics add to the incoming harmonics to create a harmonic resonance, which causes the voltage peak to be multiplied. This has formed a consensus in the industry that it is safer to install cables with a length of less than 50m, and there will be a problem of voltage multiplication for cables with an installation length of more than 50m. Therefore, the installation location of the frequency conversion device is required, and the speed-regulating permanent magnet eddy current drive itself does not use electricity; the retrofit of the old unit only needs to move the motor backward.
9) The frequency conversion device is the source of harmonic pollution, and the speed-regulating permanent magnet eddy current transmission device is green and environmentally friendly. Without any pollution. It is fully in line with the country's industrial policy.
●Comparison of speed-regulating magnetic couplings and speed-regulating hydraulic coupling
1) The hydraulic coupling uses oil, which is easy to leak and pollutes the environment; the permanent magnet eddy current transmission device does not use oil and has no leakage, which is a green product.
2) There are many failure points of the hydraulic coupling, such as: oil pumps, seals, etc., and the maintenance cost is high; the maintenance cost of the permanent magnet eddy current transmission device is low.
3) The hydraulic coupling itself has a large loss: slip loss, friction and impact loss of the working oil when torque is transmitted, power consumption loss of the oil pump, and its own mechanical loss; while the permanent magnet eddy current transmission device only has slip loss and its own mechanical loss; Compared with the hydraulic coupling, the permanent magnet eddy current transmission device has about 15% more energy-saving effect.