If you put two magnets in close proximity to each other, you know that they’ll experience an attractive force when opposite poles are near each other and a repulsive force when like poles are near. If you hold one magnet stationary and rotate the other, pole-over-pole, the rotating magnet will tend to stop when its […]
AC Motors
AutomationDirect adds more premium efficiency IronHorse AC motors
AutomationDirect’s IronHorse line of general-purpose three-phase motors now includes the MTRP-series 56HC-frame premium efficiency motors available from 1 to 3 hp. The rolled steel motors are available in 1,800 and 3,600 rpm models and feature 4:1 constant torque and 10:1 variable torque speed ranges, TEFC frames, cast aluminum end bells and removable mounting bases. MTRP-series […]
How to use servo drives with asynchronous (induction) motors?
With high construction costs of rare earth permanent magnet synchronous servo motors, asynchronous (induction) motors are more acceptable, when possible. By Craig Dahlquist • Application Engineer at Lenze Americas One way to get servo control of an asynchronous motor (on 400 to 480 Vac supply voltage) is to use a conventional 230/400 or 230/460 Vac (delta/wye connection) […]
FAQ: When to use a DC drive vs an AC flux-vector drive
DC drives are known for their ability to provide tight speed control and full torque at any speed, whereas traditional AC drives had a more narrow speed range and limited torque control. But newer AC drives using vector control, also known as field oriented control (FOC), have performance similar to DC motor and drive systems. Through […]
FAQ: What are current source inverters and voltage source inverters?
As we’ve discussed before, the main components of a variable frequency drive (VFD) are a rectifier (also referred to as a converter), which converts AC voltage to DC voltage, a DC bus (also referred to as a DC link), which filters and stores the DC power, and an inverter, which converts the DC power back to […]
FAQ: How does EU Regulation 428/2009 apply to AC drives?
AC drives capable of operating at frequencies of 600 Hz or greater are generally referred to as “high-frequency” drives. These drives are considered by the U.S. and the EU to be dual-use devices, meaning that although they are commonly used in civilian applications, such as industrial equipment, they can also be used in military applications or […]
What are VFD reflected waves and why are they harmful?
Reflected waves, also known as transmission line effects or standing waves, are over-voltages that can damage the motor and cable. The use of IGBTs (insulated gate bipolar transistors) in variable frequency drives has helped to improve VFD performance in several ways. First, their quick switching time (also referred to as rise time, or dV/dt) means […]
FAQ: What is a VFD line reactor?
Many of the components that make up a variable frequency drive (VFD) are semiconductor components, which are sensitive to power or current surges, voltage spikes, line distortion, and general power anomalies. A line reactor is an optional component that can be added to a drive system to protect the VFD and other devices from power […]
What is a rectifier?
AC motors can be operated directly from AC supply voltage, but this is only suitable if the motor is required to run at constant speed. If the speed or load requirements of the motor change, an AC drive — also referred to as a variable frequency drive (VFD) — can vary the voltage and frequency […]
FAQ: What is dynamic braking and when is it used?
When a motor is in an overhauling condition—that is, the load is moving faster than the designated motor speed—the motor acts as a generator and produces electrical energy from mechanical energy. This electrical energy, however, needs somewhere to go, and the most common way of dealing with its release is through dynamic braking. How dynamic […]
