There are four internal losses that contribute to lower efficiency of a DC generator. Copper losses Eddy-current losses Hysteresis losses Mechanical losses Copper Losses Copper loss is the power lost as heat in the windings; it is caused by the flow of current through the coils of the DC armature or DC field. This loss …
Three phase induction motors – Operating principle
What is the operating principle of a 3ph induction motor? An electric motor converts electrical energy into a mechanical energy which is then supplied to different types of loads. A.c. motors operate on an a.c. supply, and they are classified into synchronous, single phase and 3 phase induction, and special purpose motors. Out of all …
Synchronous Motor Construction
General Synchronous motors convert electrical power to mechanical power; synchronous generators convert mechanical power to electrical power; and synchronous condensers supply only reactive power to stabilize system voltages. Synchronous motors, generators, and condensers perform similarly, except for a heavy cage winding on the rotor of motors and condensers for self-starting. A rotor has physical magnetic poles, arranged to have …
How to select AC converter for VSD?
Altough manufacturers’ catalogues try to make it easy as possible, there are many variables associated with the selection and rating of the optimum electric motor and AC converter for a Variable Speed Drive (VSD) application. In many cases, it requires considerable expirience to get the selection right. The reason why it is difficult is because …
NEC Code for Size of Cable for Motor
NEC Code 430.22 (Size of Cable for Single Motor) Size of Cable for Branch circuit which has Single Motor connection is 125% of Motor Full Load Current Capacity. Example What is the minimum rating in amperes for Cables supplying 1 No of 5 hp, 415-volt, 3-phase motor at 0.8 Power Factor. Full-load currents for 5 …
The Cage Induction Motor Explained In Details
This simplest form of ac induction motor or asynchronous motor is the basic, universal workhorse of industry. Its general construction is shown in Fig. 1. It is usually designed for fixed-speed operation, larger ratings having such features as deep rotor bars to limit Direct on Line (DOL) starting currents. Electronic variable speed drive technology is …
Motor starting problem and high motor inrush currents
Electric motor protection device depends on the accurate and correct selection of overload(s), fuses and/or circuit breakers. Over the years the protective devices have been selected according to the applicable code requirements with only minimal nuisance tripping. However, in recent years, the problem of nuisance tripping due to the high motor inrush currents that occur …
What is the major difference between a two-phase and a three-phase stator?
Rotor Behavior In a Rotating field For purposes of explaining rotor movement, let’s assume that we can place a bar magnet in the center of the stator diagrams of figure 0. We’ll mount this magnet so that it is free to rotate in this area. Let’s also assume that the bar magnet is aligned so …
5 steps to choose best motor for your application
Step 1: Know the load characteristics For line-operated motors, loads fall into three general categories: constant torque, torque that changes abruptly, and torque that change gradually over time. Bulk material conveyors, extruders, positive displacement pumps, and compressors without air unloaders run at relatively steady levels of torque. Sizing a motor for these applications is simple …
Why do we need variable speed drives (VSD)?
Reasons for using variable speed drives There are many and diverse reasons for using variable speed drives. Some applications, such as paper making machines, cannot run without them while others, such as centrifugal pumps, can benefit from energy savings. In general, variable speed drives are used to: • Latch the speed of a drive to …
