The traditional method of starting an AC induction motor “across the line” results in full voltage, current, and torque being applied immediately when the motor is started, and likewise, being removed immediately when the motor is stopped. While this is the most simple starting method, the high inrush current (often 6 to 7 times the […]
What is DC injection braking and how does it compare with other methods?
AC induction motors excel at driving high-inertia loads at high speeds — in fans, saws, conveyors, and mills, for example — and variable frequency drives make it possible to match the motor speed to the application requirements by varying the frequency of the supplied voltage. But when quick stops are needed — whether for safety reasons or […]
What do IP ratings really mean, and how do they differ from NEMA ratings?
Electrical enclosures, such as those for motors, sensors, and HMIs, are often given what is known as an IP rating, consisting of the two letters, “IP,” followed by two numeric digits — IP65, for example. This IP rating indicates the amount of protection the enclosure provides against the ingress of solid particles and liquids. Unlike […]
What is an LVDT (linear variable differential transformer)?
A linear variable differential transformer (LVDT) is an absolute measuring device that converts linear displacement into an electrical signal through the principle of mutual induction. Its design and operation are relatively simple, providing extremely high resolution in a device suitable for a wide range of applications and environments. The main components of an LVDT are […]
What are chain-on-edge conveyors and where are they used?
Conveyors are the backbone of many factories, moving parts and materials through assembly or processing stations via chains, rollers, belts, or pallets. Most conveyor designs hold the part stationary, in a given orientation, as it moves down the line. And in many processes, maintaining a fixed orientation is important — when a part is being […]
Control Techniques announces new servo drive
Control Techniques, part of the Nidec group of companies, has revealed its new generation of advanced servo drive technologies. The new Digitax HD servo series delivers ultimate motor control performance and flexibility from a uniquely compact package. Targeting high axis count automation systems, Digitax HD provides all of the benefits of a modular system with […]
What is meant by the term General Motion Control?
There are numerous interpretations of what the motion control market entails in terms of products included and industries served, but there are some commonalities among the various definitions. First, a motion control system includes at least three basic components — a motor, a drive, and a controller. Second, motion control systems are primarily used in discrete […]
What are coreless DC motors?
A typical brushed DC motor consists of an outer stator, typically made of either a permanent magnet or electromagnetic windings, and an inner rotor made of iron laminations with coil windings. A segmented commutator and brushes control the sequence in which the rotor windings are energized, to produce continuous rotation. Coreless DC motors do away […]
What are leading methods for VFD control of AC motors?
AC motors are often used in equipment that runs at constant speed regardless of load, such as fans, pumps, and conveyors. But when speed control is required, an AC motor is paired with a variable frequency drive (VFD), which regulates the motor’s speed by using one of two control methods — scalar control or vector […]
What are rotary unions and how are they used in motion applications?
Rotating components are common in motion applications — robot arms, winders, spools, spindles, and rotary tables are just a few examples. And while creating rotary motion is easy, when air or liquids need to be transferred from a stationary supply to a rotating component for cooling, heating, lubricating, or transmitting fluid power, the task becomes […]