Energy Savings

Q. How Does The Magnetic-Coupled Drive Save Energy If The Motor Runs Continuously?

Because of the nature of the descending torque load itself, the magnetic-coupled drive takes advantage of the energy savings with variable speed.

The magnetic-coupled drive will take advantage of the affinity laws on variable torque loads such as centrifugal fans and pumps and does so without altering the voltage or interrupting power to the motor. Even with the motor running continuously, the kW required by the motor changes according to the actual load; i.e., loading and unloading of the motor by varying the speed of the load via magnetic coupling between the motor end the load. What you always pay for is the amount of kW used and even with the motor running continuously, the difference in the amount of kW that required of any 3 phase motor from no load to full load is very significant.

As example: 7-1/2 hp motor/3-phase/60hz (typical blower application)

Measured @ full load, max fan speed (typical) = 5.60 kW

Measured @ min load, min fan speed = approximately 0.40 to 0.50 kW

Greater than 10 to 1 kW difference throughout entire speed range, thanks to the affinity laws. Even greater advantages from full load to no load are realized as the motor horsepower size increases. As a result, the power curves are very similar to vfd's on variable torque loads and the kW savings are significant as well. As a general rule, magnetic-coupled drives are more efficient at the top end of the curve, and the vfd's are more efficient further down the curve.

Q. Does The Magnetic-Coupled Drive Cause Additional Motor Heating, Even At Very Low Speeds?

The magnetic coupling is electrically isolated from the motor and in effect operates as an infinitely variable; frictionless clutch, allowing tie motors to operate as originally designed at full speed continuously, end with pure uninterrupted AC power. Regardless of the drives' operating speed, the motor never sees any additional heating contributed by the drive. In fact, the drive itself via slip, and not the motor dissipate any additional heat. Since these new drives are efficiently sized to handle the full rated horsepower of this types of loads, the minimum amount of drive heating is effectively dissipated by the drives' own integral fan. Since the motor runs continuously end the drive is simply controllably coupling and uncoupling the load, the effect of the motor loading is no difference in operation than if you had incorporated an infinite number of pulley sizes to provide variable speed to the load.

Q. Power Quality Issues, Harmonics?

Since the magnetic-coupled drive does not interrupt the power source to the motor, there are no current harmonics produced nor is there any resultant voltage distortion. There is never any need for filters, reactors, or full rated 3 phase isolation transformers.

Q. How Far Can The Controller Be Located From The Motor? Are There Any Limitations?

The distance from the controller to the magnetic drive and motor has worked successfully at distances up to 2000 feet. The only requirement is that the two wires that provide power to the drive coil be sized large enough to allow for any voltage drop (say 14 gauge, typically). No filters or any other devices are required. There is no concern about ever causing any damage to the motor or drive.

Q. What About Nuisance Dropouts?

By virtue or the inherently simple design, the drive is always active as long as the motor starter is en ergized. Transient over voltages, voltage sags, and harmonic distortion from other sources generally do not effect magnetic-coupled drives unless the duration is long enough to drop out the motor starter circuit.

Q. Lightning?

Since eddy-current drives are isolated from the power source, they provide the highest level of immunity to the effects of lightning.

Q. Retrofit Existing Motors?

The shaft-mounted magnetic-coupled drive allows for true variable speed retrofit of any existing motor. There is never any need for inverter duty motors. All original motor wiring circuitry can always remain undisturbed.

Q. Bypass?

A simple mechanical full speed lock-up feature is standard on all drives. Full speed electrical bypass can be accomplished with one diode.

Q. Is There Any Motor Insulation Failure Or Electrical Pitting Of Motor Bearings?

Since die magnetic-Coupled drive does not electrically connect to the motor wires, there is never any possibility or causing any electrically induced harm to the motor windings or the motor bearings.

Q. What About Power Factor?

Some utility companies in certain locations may change penalty if the facility's total measured power factor is below an acceptable pre-determined level. In hundreds and hundreds of installations in many varied facilities such as colleges, schools, hospitals, government buildings, and shopping malls, power factor has never been an issue with the new shaft-mounted variable speed drives. However, in the event low power factor requires attention, low cost power factor correction capacitors can be easily installed at each motor location as required.

Q. Maintainability, In-House?

This simple technology does not require highly skilled personnel to maintain. The same compact low cost controller is used on all drive sizes 1 through 150 horsepower. Unlike high maintenance brushes and slip rings, the rotary brushless plug-in coupling cartridge can be swapped out in a matter of seconds.

Q. For Applications Other Than Variable Torque Loads, How Does The Magnetic-coupled Drive Perform?

In constant torque applications, the drive must be properly sized to allow for additional drive heat dissipation at the lower speed ranges, however there are no added demands on the motor other than the conventional no load to full load conditions, the same as in fixed speed operation considerations. These drives perform very well in many other applicators, such as conveyors, feeders, machine tools, punch-presses, etc., As variable voltage, constant current, or closed loop methods.

Q. What's New On The Horizon?

Continued development on the next generation of self-powered variable speed drives is a priority. These new magnetic coupled drives have their own source or power, an integral generator, automatically active when the motor is running. No external power source is required. Installation cost is reduced further because there is no need for the added cost of an electrician. Simply mount the drive to the motor shaft, connect the belts, end then provide a standard 4/20-ma signal to the drive. Loop powered at any horsepower. Imagine that.

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