Too much roll on a boat underway can make it hard to fish, eat, drink or even move about. So in 2003, Seakeeper began R&D on nautical motion controls to address the problem. Eventually Seakeeper developed a gyroscope that uses industrial motion products for maximum stability. According to Seakeeper, this computer-controlled gyroscope eliminates most boat […]
FAQs + basics
What kinds of encoder features boost ruggedness? Solid-state electronics, maybe?
Digital technology boosts the reliability of rotary-encoder designs. By Jeff Smoot, VP of Application Engineering & Motion Control, CUI Inc. Encoder applications are all around us, from BattleBots to the Mars Rover, large construction vehicles to semiconductor manufacturing equipment, and in numerous medical and military applications. In short, wherever there is motion, an encoder is […]
FAQ: How do I calculate the inertia of a servo-driven system?
Inertia, or more specifically, inertia ratio, is one of the most important factors in sizing a servo system. Inertia is defined an object’s resistance to change in velocity, and in servo-driven systems, it can be used as a measure of how well the motor is able to control the acceleration and deceleration of the load. […]
FAQ: What are PLC function blocks and how does IEC 61131-3 classify them?
According to the IEC 61131-3 standard, there is a difference between a function and a function block in PLC programming. The main difference involves internal memory. So for instance, a function can be described as something like an equation or formula that accepts inputs and calculates an output value. Moreover, it always returns the same […]
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 […]
PLC versus safety PLC
All PLCs (programmable logic controllers) do essentially the same thing; control some machine process. Typical PLC functions include timing, control, and sequencing of such actions as turning motors, pumps or valves on or off. A safety PLC, on the other hand, is a dedicated controller specifically built and certified to meet safety requirements, such as […]
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 […]