ABB’s AXW 5000 and 5800 motors offer more horsepower per pound than conventional totally enclosed fan cooled (TEFC) motors but with a smaller frame size. This helps save space, up to 8 in. in overall length in some cases, which enables more compact installations. Advantages of AXW motors include higher power densities, smaller overall footprint […]
What is direct torque control (DTC) for AC induction motors?
Variable frequency drives control AC induction motors through one of several control schemes. Scalar control (also referred to as V/Hz or V/f control) varies both the voltage and frequency of power supplied to the motor to maintain a fixed ratio between the two. This keeps the strength of the magnetic field at a constant level […]
What is a DC bus choke and why is it used?
In a recent post, we looked at motor chokes — inductive devices installed between a drive and motor — and why they’re used in servo systems and variable frequency drives. But in variable frequency drives (VFDs), inductors can also be placed after the drive’s input diodes, between the input rectifier and the DC bus link. […]
What is a motor choke and why is it used?
A choke is a passive device that adds inductance to a circuit. Inductance is a property of a coil of wire that resists any change to the current flowing through it. (Straight wires also possess a small amount of inductance.) In other words, if current through the coil increases, the magnetic field of the coil […]
Open drip proof and 4-in-1 motors from AutomationDirect
AutomationDirect has extended the line of Marathon motors to include open drip proof (ODP) and 4-in-1 series ac motors. ODP motors are available in single phase, rigid base and C-face footed (rigid base) versions with NEMA Service Factor ratings. 4-in-1 motor configurations include single-phase, totally enclosed motors; and XRI 4N1 general purpose, 3-phase, totally enclosed […]
AC induction motor inertia: What’s the difference between WK2 and WR2?
In any motor-driven system, the difference between the motor inertia and the load inertia will affect the system’s performance — especially its ability to accelerate the load quickly and efficiently. While servo motors are the preferred choice for applications that specify a precise move profile, AC induction motors are often the better choice for applications […]
What is droop control in the context of AC motors and drives?
One of the fundamental characteristics of an AC induction motor is that the rotor spins at a slower rate than that of the stator’s rotating magnetic field. This difference in speed between the rotor and the stator’s magnetic field is known as slip. Slip allows the motor to produce torque — the higher the slip, […]
Bison Gear and Engineering launches next-generation permanent magnet ac motor
At the Automate Trade Show, Bison Gear and Engineering announces the launch of VFsync, a next-generation permanent magnet ac motor. Designed for today’s demanding machine drive applications, the new synchronous motors run at high efficiency with advanced variable frequency drives. The IP66/IP54 platform of three-phase motors range in power from 0.25 to 1.5 hp, and […]
Motion Trends: New motor breeds are smart, connected, and compact
This year’s survey of trends in electric motors for motion control and automation revealed several trends and emerging developments in the use of synchronous ac motors; stepper motors, especially in closed-loop offerings; brushless motors of various types; and a smattering of specialty direct-drive offerings just making inroads. Proliferation of synchronous ac motors With construction and […]
What is plugging for electric motors?
There are generally three types of electrical braking for motors: regenerative braking, dynamic braking, and plugging. Of the three methods, plugging provides the fastest stop, but it can be harsh on both the electrical and mechanical components. Because of this, it’s the least commonly used method of braking, but it is appropriate for some applications. […]
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