PERMANENT MAGNETIC COUPLING
What is Magnetic Coupling?
A magnetic coupling is a Coupling that moves torque from one shaft onto the next, it transfers power to centrifugal pumps (also known as magnetic drive pumps or magnetic pumps). However, Magnetic Couplings use magnetic field and not a physical mechanical connection. It basically consist of a primary part which is inflexibly associated with the motor shaft, and another part which is arranged on a shaft along with the impeller. Here, both of the parts are attached with permanent magnets. Poles of inverse polarity face one another. They draw in one another because of the magnetic transition. At the point, where the first part is driven, the another second part rotates simultaneously.
How does a magnetic Coupling works?
The major purpose of the Permanent Magnetic coupling is to join two shafts of various components together to transfer movement and power. Usually all sorts of conventional Couplings are in the form of contact couplings. Magnetic Couplings can be divided into rigid couplings and flexible couplings, based upon if they have elastic parts inside. The elastic Coupling has elastic parts inside it, which are made up of rubber plastics metal springs, thus it has the capacity of buffering the vibration assimilation and the capacity to adjust to the axis deviation. It is appropriate for applications subject to variable burden impact and sudden beginning and reversing. It is also useful in applications in which 2 axis can’t be stringently aligned. There is no versatile part or elastic part in the rigid coupling, making it unable to absorb vibration.
Permanent Magnetic coupling working principle
It is a Gap based coupling i.e. No physical connection between motor and loaded equipment rotating is required. It works on the principle of Arago’s disc. When a disc made of copper or aluminum is sandwiched between magnets and magnets are moved, eddy currents are generated on the disc and this current causes the force that tries to move the disc in the moving direction of magnets to be generated on the disc.
PMC technology is equipped with permanent magnets made from ferromagnetic materials to create an induced magnetic force used for torque transfer. PMC physically separates the elements of the motor system and load side, coupling the load shaft and the motor shaft eradicating any physical contact (i.e. by electromagnetism). Motor torque is transferred to the load side across an adjustable gap. Varying the gap between the magnets and conductor changes the strength of the magnetic field and hence controls output speed. Meanwhile, by changing the strength of the magnetic field getting torque change.
“As the gap between metal plate and magnet increases, RPM on the load side decreases, & hence current consumption reduces. That is how PMC save energy.”
Kimax is the leading Permanent Magnetic coupling manufacturer & Supplier and Magnetic coupling exporter.
Types of Permanent Magnetic Coupling
A. Permanent Magnet Coupling - Fixed Gap
Kimax is the manufacturer of Magnetic Coupling and this is a basic type of Permanent magnetic coupling. After studying the process parameters of the pump system and understanding the needs of the plant, A fixed Gap PMC is designed. The Gap between the metal plate and Magnet can be changed manually after the motor is stopped.
B. Permanent Magnet Coupling - Adjustable Gap
In this advance type of PMC, the Gap between Metal plate & Magnet can be changed using an actuator during the continuous pump system. Whenever plant requires to increase the output, the GAP between Metal plate & Magnet can be reduced from control room or using the remote/mobile application of the Intelligent Actuator. And when demand decreases and plant operator wants to reduce the energy consumption, then GAP can be increased similarly. (electro-mechanical coupling)
Magnetic coupling applications
- To replace the highly sensitive & expensive fluid coupling or variable frequency drive(VFD) to save energy.
- Throttling valve needs to be operated very often due to big designed capacity or reduced demand, use of adjustable gap PMC can be an effective solution instead of throttling valve operation.
- Change process or system’s output speed over a period of time.
- Difficult to solve the misalignment that causes wear and tear on coupling.
Features of Permanent Magnetic Coupling
- Energy cost saving from 5% up to 50% by changing the gap.
- Soft start with less impulse current on power grid and reducing mechanical stresses of system.
- Reliable in harsh or dirty environment no matter outdoor or indoor.
- Automatic slip through upon overload which ensures the reliability of motor driving system.
- Simple structure and no electronic components which keep the equipment with long life.
- Higher performance in vibration reduction by non-contact air gap by torque transmission.
- The most economic cost, easy installation and no maintenance required.
- No electromagnetic interference and harmonic current to other components near to PMC.
Permanent Magnet Coupling v/s Variable Frequency Drive v/s Fluid Coupling
|Operating Principle||Torque transmission by gap (no contact)||Electrical component control multi-frequency||Control and adjust fluid volume|
|Control flow, pressure & automatic control||Yes||Yes||Yes|
|Adapt to environment & Vibration Reduction||Good||Bad||Normal|
|Increase life of Bearing & Seal||Yes||No||Yes|
|Frequent stop /start||Yes||No||Yes|
|Life||>20years||5-10 years||5-10 years|
|Alignment time of axial||Easy||Hard||Hard|
|Protection||No need||Air conditionPrevent dust, lightning/thunder||Prevent leakage, burning|
|Difficulty in troubleshooting||Easy||Hard||Middle|
|Input power factor||Equal to motor||Less than motor||Equal to motor|
|Input voltage sensitivity||No||Yes||No|
|Energy efficiency||(1-speed ratio 2) * efficiency||(1-speed ratio 3) * efficiency||(1-speed ratio 2) * efficiency|
|Emi and harmonic current||No||Yes||No|