1. The Forth Military World Games were held in October, 2007 in India at (a) Hydrabad (b) Chennai (c) Ahmedaba (d) Lucknow 2. Who of the following received the Sanskriti Award for 2007 in the field of literature? (a) Jyotshna Kalita (b) K.A. Shaji (c) K.P. Reji (d) Bijayini Satpathy 3. The legislative Council in […]
1. The best conductor of heat among liquids is (a) water (b) mercury (c) ether (d) alcohol 2. The layer of the atmosphere which reflects ratio waves back to the earth is called (a) Stratosphere (b) Tropopause (c) Ionosphere (d) Troposphere 3. An object weigth maximum in (a) air (b) water (c) hydrogen (d) vacuum
This article focuses on a motor intended for motion control—the servomotor, or servo. Whereas stepper motors rotate through an angle and halt, many servo motors rotate continuously. Properly controlled, a servo can do everything a stepper can and more. In addition to setting the rotation angle, the controller can configure the servo’s rotational speed and
A stepper motor’s purpose is to rotate through a precise angle and halt. The speed and torque of the rotation are secondary concerns. As long as the stepper rotates through the exact angle and stops, its mission is accomplished. Each turn is called a step, and common step angles include 30°, 15°, 7.5°, 5°, 2.5°,
Stepper Motor Control Because VR steppers are so scarce, this article focuses on controlling PM and HY steppers, which are almost always two-phase motors. Some PM and HY steppers are bipolar and have four wires. Others are unipolar and have five or six wires. The terms bipolar and unipolar identify how the wires are connected
The twentieth century brought about a revolution in electronics, as researchers used solid state physics to miniaturize transistors and other circuit elements. With these new integrated circuits, engineers were able to design systems more complex than anything dreamed of before. As circuit designs grew in complexity, so did the designs of electric motors. In 1962,
Metal-core printed circuit boards or MCPCB are increasingly being used in power electronics due to their superior thermal performance. Effective thermal management is critical to ensure the long-term reliability of power electronics, and thermal simulation and optimization can be used to improve the thermal performance of MCPCBs. This article discusses the importance of thermal simulation
Transient Performance of Stepping Motors Step Response It was pointed out earlier that the single-step response is similar to that of a damped second-order system. We can easily estimate the natural frequency ωn in rad/s from the equation Knowing ωn, we can judge what the oscillatory part of the response will look like, by assuming
Drive Circuits and Pull Out Torque Speed Curves Users often find difficulty in coming to terms with the fact that the running performance of a stepping motor depends so heavily on the type of drive circuit being used. It is therefore important to emphasise that in order to meet a specification, it will always be
Characteristics of Stepping Motors Static Torque–Displacement Curves From the discussion in previous article, it should be clear that the shape of the torque–displacement curve, and in particular the peak static torque, will depend on the internal electromagnetic design of the rotor. In particular the shapes of the rotor and stator teeth, and the disposition of