Electric Motor
Internal losses that reduce efficiency of a DC generator
There are four internal losses that contribute to lower efficiency of a DC generator. Copper losses Eddy-current losses Hysteresis losses Mechanical losses Copper loss is the power lost as heat in the windings; it is caused by the flow of… Read more
Feb 03, 2012 | By Edvard Csanyi
Electric Motor
Three phase induction motors – Operating principle
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… Read more
Feb 03, 2012 | By Henry James
Energy and Power
Using VLT AQUA Drive in submersible pump application
The system consists of a submersible pump controlled by a Danfoss VLT AQUA Drive and a pressure transmitter. The transmitter gives a 4-20 mA feedback signal to the VLT AQUA Drive, which keeps a constant pressure by controlling the speed… Read more
Jan 30, 2012 | By MarkoCvrkota
Electric Motor
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… Read more
Jan 06, 2012 | By Edvard Csanyi
Electric Motor
NEC Code for Size of Cable for Motor
Size of Cable for Branch circuit which has Single Motor connection is 125% of Motor Full Load Current Capacity. What is the minimum rating in amperes for Cables supplying 1 No of 5 hp, 415-volt, 3-phase motor at 0.8 Power… Read more
Dec 30, 2011 | By Jignesh Parmar
Electric Motor
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… Read more
Dec 23, 2011 | By Edvard Csanyi
Electric Motor
Major difference between a 2-phase and a 3-phase stator
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… Read more
Dec 17, 2011 | By Edvard Csanyi
Electric Motor
5 steps to choose the best motor for your application
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… Read more
Dec 03, 2011 | By Edvard Csanyi
Electric Motor
Why do we need variable speed drives (VSD)?
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… Read more
Nov 25, 2011 | By Edvard Csanyi
Energy and Power
How contactor controls an electric motor?
When a relay is used to switch a large amount of electrical power through its contacts, it is designated by a special name: contactor. Contactors typically have multiple contacts, and those contacts are usually (but not always) normally-open, so that… Read more
Jun 01, 2011 | By Edvard Csanyi
Energy and Power
Moisture Effect On Insulation Of Generator
Moisture, which can enter the insulation of a generator or motor winding from damp air or which can enter the winding of a transformer from wet oil, will make a surprisingly large difference in the insulation resistance. This is clearly… Read more
May 13, 2011 | By Edvard Csanyi
Electric Motor
Basic construction of 3-phase AC induction motors you should know
For industrial and mining applications, 3-phase AC induction motors are the prime movers for the vast majority of machines. These motors can be operated either directly from the mains or from adjustable variable frequency drives. In modern industrialized countries, more… Read more
Apr 18, 2011 | By Edvard Csanyi
Electric Motor
VSD – Power supply connections and earthing
In accordance with accepted practice and the local, power is normally provided to a VSD from a distribution board (DB) or a motor control center (MCC). Adequate arrangements should be made to provide safety isolation switches and short-circuit protection in… Read more
Apr 13, 2011 | By Edvard Csanyi
Electric Motor
Induction machines – historical touch
Faraday discovered the electromagnetic induction law around 1831 and Maxwell formulated the laws of electricity (or Maxwell’s equations) around 1860. The knowledge was ripe for the invention of the induction machine which has two fathers: Galileo Ferraris (1885) and Nicola… Read more
Mar 15, 2011 | By Edvard Csanyi
Electric Motor
Operating Principle Of Three Phase Asynchronous Motors
The operating principle of an asynchronous motor involves creating an induced current in a conductor when the latter cuts off the lines of force in a magnetic field, hence the name “induction motor”. The combined action of the induced current… Read more
Feb 02, 2011 | By Edvard Csanyi
