Armature reaction drop

Armature reaction drop

Armature reaction drop is the effect of a magnetic field on the distribution of the flux under main poles of a generator. [cite book|title=Basic Electricity |author= A.Van Valkenburgh|year=1993|publisher=Thomson Delmar Learning|url=http://books.google.com/books?vid=ISBN0790610418&id=vmg1UKsTntAC&pg=PT666&lpg=PT666&ots=BpGdNz1lT0&dq=Armature+Reaction+Drop&ie=ISO-8859-1&output=html&sig=UPP07UxX3VLD3nmIZxUexDnnZ9A|id=ISBN 0790610418]

ee also

* Armature (electrical engineering)₴Since an armature is wound with coils of wire, a magnetic field is set up in the armature whenever a current flows in the coils. This field is at right angles to the generator field, and is called cross magnetization of the armature. The effect of the armature field is to distort the generator field and shift the neutral plane. The neutral plane is the position where the armature windings are moving parallel to the magnetic flux lines. This effect is known as armature reaction and is proportional to the current flowing in the armature coils.The brushes of a generator must be set in the neutral plane; that is, they must contact segments of the commutator that are connected to armature coils having no induced emf. If the brushes were contacting commutator segments outside the neutral plane, they would short-circuit "live" coils and cause arcing and loss of power. Armature reaction causes the neutral plane to shift in the direction of rotation, and if the brushes are in the neutral plane at no load, that is, when no armature current is flowing, they will not be in the neutral plane when armature current is flowing. For this reason it is desirable to incorporate a corrective system into the generator design.These are two principal methods by which the effect of armature reaction is overcome. The first method is to shift the position of the brushes so that they are in the neutral plane when the generator is producing its normal load current. in the other method, special field poles, called interpoles, are installed in the generator to counteract the effect of armature reaction.The brush-setting method is satisfactory in installations in which the generator operates under a fairly constant load. If the load varies to a marked degree, the neutral plane will shift proportionately, and the brushes will not be in the correct position at all times. The brush-setting method is the most common means of correcting for armature reaction in small generators (those producing approximately 1000 W or less). Larger generators require the use of interpoles.

References

From Basic Electrical Systems

In some cases,Compensating Windimgs are also placed in the slots of the main pole's face to eliminate cross magnetising effect & Armature Reaction


Wikimedia Foundation. 2010.

Поможем написать курсовую

Look at other dictionaries:

  • Armature (electrical engineering) — In electrical engineering, an armature is one of the two principal electrical components of an electromechanical machine a motor or generator. The other is the field winding, field magnet. The role of the field component is simply to create a… …   Wikipedia

  • Commutator (electric) — This article is about the electrical component. For mathematical concept, see Commutator . A tiny 5 segment commutator less than 2 mm in diameter, on a direct current motor in a toy radio control ZipZaps car. A commutator is a rotary electri …   Wikipedia

  • History of electrochemistry — Electrochemistry, a branch of chemistry, went through several changes during its evolution from early principles related to magnets in the early 16th and 17th centuries, to complex theories involving conductivity, electrical charge and… …   Wikipedia

  • electromagnetism — /i lek troh mag ni tiz euhm/, n. 1. the phenomena associated with electric and magnetic fields and their interactions with each other and with electric charges and currents. 2. Also, electromagnetics. the science that deals with these phenomena.… …   Universalium

  • Big Thunder Mountain — Pour les articles homonymes, voir BTM. Big Thunder Mountain (BTM) ou Big Thunder Mountain Railroad est une attraction de type montagnes russes des parcs Disney Royaume Enchanté. C est un « train fou » lancé dans une mine du Far West, ce …   Wikipédia en Français

  • quadrature reactance — A term used in the two reaction theory of synchronous machines to denote the ratio which the synchronous reactance drop produced by the quadrature component of the armature current bears to actual value of quadrature component …   Dictionary of automotive terms

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”