Eddy Current Drives


IDEAL Eddy Current Variable Speed Drives use constant speed electric motors and a DC magnetic field to reduce speed and generate incredible amounts of torque effectively. Our drives are intended to move high-inertia loads that frequently start and stop more efficiently than variable frequency drives (VFDs) are capable of. This incredible efficiency greatly reduces lifetime costs associated with energy and maintenance, often resulting in cost savings when used in place of VFDs.






Ideal Capabilities

Up to 2250 HP
Input Speed
Up to 1800 RPM
Vertical & Horizontal
Enclosure & Cooling Methods
Eddy Current Drive


IDEAL Electric Eddy Current Drives are widely used as a cost-effective method for the variable speed control of AC motors in large-scale applications. They provide smooth, stepless, and precise speed control in addition to high overload capacity capabilities and incredible longevity. Either squirrel cage induction or synchronous motors are compatible with IDEAL Eddy Current Drives.

Drive speed can be controlled manually or automatically. Manual control is achieved by simply turning a rheostat, whereas automatic operation can be governed by liquid level, pressure, temperature, frequency, or by an electronic signal from suitable circuitry.

IDEAL Eddy Current Drives do not require high starting torque motors to function. In fact, the motor may be started at no load whatsoever. The load may be accelerated after the motor has reached full speed. Magnetic drives are well-suited for accelerating high-inertia loads, such as large flywheels and large-diameter fans.

Our Eddy Current Drives can be used to convert variable speed to constant speed. For example, they can change an unstable 50-cycle power supply to a stable 60-cycle source for computers and other precision power applications.

Additionally, IDEAL Eddy Current Drives far surpass the useful life of VFDs. Their longevity is tied to their simple, effective design – unlikely to change drastically over time. Unlike VFDs, there are Eddy Current Clutches operating currently that are well over 50 years old, which makes them an investment that easily lasts a lifetime. 

Eddy Current Drives
Ideal Electric IDEAL ELECTRIC Eddy Current Variable Speed Drives Installed 2


The IDEAL Electric Eddy Current Drive consists of two rotating elements: a field and drum, one running inside the other. The drum, fabricated from especially durable steel, is directly coupled to the drive motor and runs at motor speed. The field member runs inside the drum and is coupled to the load shaft. The adjacent images show the simplified design and construction of these IDEAL Electric drives. The advantages of this design and additional features of these drives are explained below.

Fully Supported Members

The IDEAL Electric Eddy Current Drive design places bearing supports at both ends of each rotating member, following good engineering practice. Cantilevered loads are eliminated

Larger Air-Cooled Ratings

IDEAL Electric’s single air-gap design features axial-flow air cooling. Special fans and baffles control the movements of the air which cools the drum. Exclusive double-end drum cooling with axial fins on the drum, increases thermal capacity and makes possible larger ratings in air-cooled construction

High Overload Capacity

Ideal Electric’s Eddy Current Drive design increases the coupling overload capacity. Fully supported members ensure a concentric air gap, and the drum located outside of the field means thermal expansion increases the air gap during overload. Interference or rubbing between the coupling drum and field is eliminated.

Simplified Construction

Two elements, a drum, and a laminated salient pole field make our design simpler in concept than a squirrel cage induction motor. The simplicity of this sturdy design is made possible by fabricated construction. All completed at our Ohio and Houston Works.

Flexible Design

IDEAL Electric Eddy Current Drives are performance-designed rather than mass-produced. To ensure that your exact requirements of performance and structure are met, all elements of the drives are fabricated at our Ohio or Houston Works. This ensures a sturdy structure and complete flexibility of design.

Improved Performance

For accurate speed control during load changes, the response time of the magnetic field must be minimized. The Ideal Electric Eddy Current Drive coupling design ensures a minimal response time and delivers improved performance with ease.

Ideal Electric Eddy Current Drives
Eddy Current Drive


Eddy Current Drive

Eddy Current Drives save valuable floor space and are widely used for pumping applications of all types. IDEAL ELECTRIC Eddy Current Drives are especially well adapted for this purpose because of their special bearing design. No external accessory thrust pot is required, bearing replacement is easy, and the drives may be designed so that even the lower guide bearings can be changed without lifting the unit.

IDEAL Eddy Current Drives are built only as a combination motor and coupling. They are performance-designed to meet your specific mechanical, electrical, and environmental requirements. IDEAL Electric has built Eddy Current Drives for all types of applications – giving us valuable experience when designing and fabricating your machine.

Integral Thrust Bearings

The motor coupling combination carries the weight of the rotating parts plus the hydraulic thrust of the pump, without external thrust stands. Separate bearings for up-thrust requirements are standard. Where extremely high-thrust loadings are encountered and frame size permits, Kingsbury-type thrust bearing is used. All bearings are located exterior to the rotating members for ease of inspection, maintenance, or replacement. Oil leakage is eliminated with IDEAL ELECTRIC’s proven standpipe design for oil-lubricated bearings. The lubricant is retained in a stationary oil sump. Rigid couplings between the drive motor and the eddy current coupling are eliminated as are external thrust stands. The IDEAL ELECTRIC vertical drive reduces overall space requirements and can be disassembled for easy installation.

Rugged Construction

All members of the magnetic drive are rigidly supported on both ends. There are no open end members to distort due to heating.

Temperature Protected

Due to the simplified design of the IDEAL ELECTRIC vertical high-thrust drive, bearing temperature detectors can be placed in contact with all thrust bearings.

Efficient Cooling

The IDEAL Electric Eddy Current Drive drive is cross-ventilated for efficient cooling. The motor and coupling in the drive are designed to ventilate without recirculation of cooling air.

Maximum Accessibility

The feed-back tachometer and coupling slip rings are located at the top of the drive where they are accessible for service without disassembly.

Simplified Maintenance

All bearings can be inspected, lubricated, or replaced without disassembly of the drive, making maintenance simple for any local EASA repair shops. 


IDEAL Electric Eddy Current Drives provide precise, stepless speed control using a semiconductorized controller. This controller will respond to an input “command” voltage or milliampere signal from a variety of devices. Some of these devices which can provide an electrical signal or a mechanical translation are described below.

Eddy Current Drive
Liquid Level Control

One such control is the continuous bubble type. A small tube or pipe, under air pressure, is inserted in the wet well. Maintaining a constant flow of bubbles, with decreasing or increasing liquid level, causes variation in the air pressure. This air pressure change is utilized in a pressure transmitter to signal the magnetic drive controller.

Pressure Control

Air or fluid pressure in a pressure transmitter is used to signal the magnetic drive controller. One form uses a pressure chamber such as a piston or diaphragm opposing the force of a calibrated spring. A linkage converts the motion of the piston or diaphragm into rotation of a potentiometer, which in turn controls the signal.

Temperature Control

A commonly used temperature control is a gas pressure device. The gas is part of a closed system with a bulb or cylinder located at a point of temperature measurement. Expansion or contraction of the gas with temperature change actuates a potentiometer and changes the electrical signal to the magnetic drive controller

Frequency Control

A suitable frequency sensing circuit actuates the magnetic drive controller. The drive then becomes a speed adjusting link between the generator and its driver to maintain the desired frequency.

Electronic Control

Suitable electronic circuitry provides an adjustable signal to the magnetic drive controller. When magnetic drives are operated by a computer system, the electronic control is usually an integral part of this system.

Manual Control

Speed is controlled by manually turning a small rheostat or potentiometer. Manual speed control can be of the regulated or non-regulated type. When the non-regulated type is used, speed will vary with the amount of load. With the regulated type, the regulator will hold the speed within ± 2% of the maximum speed at any preset speed. Special controllers and magnetic drives are available when better regulation
is required.


Eddy Current Drive

Municipal and Industrial water and sewage pumping, flood control, the manufacturing of steel, paper, and other products which require large volumes of water under constant pressure with a wide fluctuation of flow requirements.

Driving Machinery

Drives of all types for use in steel mills, paper mils, cement mills, power plants, printing presses, metalworking presses, conveyors, and all types of automated machinery and other equipment.

Fans, Blower, & Compressors

For driving equipment used for heating, ventilating, and air conditioning of buildings, factories, and mines.

Frequency Changers and Stabilizers

Ideal Electric Eddy Current Drives can be inserted between the drive motor and one or more generators in motor-generator sets to serve such varied purposes as to produce precise 400-cycle power, to convert unstable 50-cycle power to precise 60-cycle power, to convert unstable 60-cycle power to precise 60-cycle power, to produce adjustable frequencies for testing or for speed control, and to drive generators at a constant speed with expander engines in air liquefaction plants.


Our expert IDEAL Electric Associates are here to support you in our Mansfield, Ohio, Houston, Texas and our European bases. Give us a call or e-mail us today!


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