The Standard Electrical Dictionary Part 11

Armature, Intensity.

An armature wound for high electro-motive force. A term little used at the present time.

Armature Interference.

A limit to the ampere turns permissible on a given armature is found in the increase of cross magnetizing effect, q. v., the increased lead necessitated, and the growth of the demagnetizing power. All such perturbing effects are sometimes expressed as armature interference.

46 STANDARD ELECTRICAL DICTIONARY.

Armature, Load of.

The circ.u.mflux, q. v., of the armature, or the ampere turns of the same.

The maximum load which can be carried by an armature without sparking is directly proportional to the radial depth of core and to the length of the gap, and inversely proportional to the breadth of the polar span.

Armature, Multipolar.

An armature in which a number of poles greater than two is determined by the field. A multipolar field is employed for its production.

Armature, Neutral.

An armature of a magnet or telegraph relay which is not polarized or magnetized.

Synonym--Non-polarized Armature--Neutral Relay Armature.

Armature of Influence Machine.

Pieces of paper pasted on the stationary plate of an electric machine of the Holtz type.

Armature of Leyden Jar or Static Condenser.

The inner and outer tin-foil coatings of a Leyden jar or other condenser.

Armature, Open Coil.

An armature of a dynamo or motor on which the coils are not joined in one closed circuit, but have their ends or some of them separated, and connected each to its own commutator bar or each set to their own bar.

Fig. 27. OPEN COIL RING ARMATURE.

47 STANDARD ELECTRICAL DICTIONARY.

Armature, Pivoted.

An armature for an electro-magnet mounted on a pivot, which is at right angles to the yoke or parallel with the legs of the magnet, so as to be free to rotate. When the magnet is excited the armature is drawn into line or approximately so with its base or yoke. The system is used in some telegraph apparatus.

Armature Pockets.

s.p.a.ces or recesses in armatures provided for the reception of the coils.

Armature, Polarized.

An armature made of steel or having a steel core to which permanent magnetism has been imparted. Such are used in some forms of magneto current generators, and in telegraphic instruments. (See Relay, Polarized.)

Armature, Pole.

An armature having coils wound on separate poles projecting radially all around the periphery of its central hub or disc, or projecting internally from a ring-like frame, their ends facing the field magnet.

Synonym--Radial Armature.

Armature, Quant.i.ty.

An armature of a dynamo or motor wound for current of large quant.i.ty.

The term is now but little used.

Armature-Reactions.

When an armature is running in an active dynamo a series of reactions is established, the more important of which are: I. A tendency to cross-magnetize the armature.

II. A tendency to spark at the brushes.

III. A tendency for the armature current to demagnetize on account of the lead which has to be given to the brushes.

IV. Variations in the neutral points as more or less current is taken from the machine.

V. Heating of armature, both core and conductors, and of pole pieces, which heating is due to Foucault currents.

Armature, Revolving, Page's.

An early form of motor. The field is produced by a permanent magnet.

Above its poles is a soft iron armature wound with a coil of insulated wire. A two-part commutator with contact springs conveys the current to the coil. The whole is so arranged that the polarity of the armature, as induced by the coil, through which a current is pa.s.sed, is reversed as its ends sweep by the poles of the magnet. Then it is repelled from the poles and swings through 180? to have its polarity reversed and to go through the next 180?, and so on. Thus it rotates at a very high rate of speed.

In the cut showing the elevation A, B, is the armature; f, g, the springs or brushes; h, the commutator with its sections o, i. In the section of the commutator W, W, designate the springs or brushes, A, the vertical spindle carrying the armature and commutator, and S, S, the commutator sections.

48 STANDARD ELECTRICAL DICTIONARY.

Fig. 28. PAGE'S REVOLVING ARMATURE.

Fig. 29. SECTION OF COMMUTATOR OF PAGE'S REVOLVING ARMATURE.

W, W, Brushes; A, Spindle; S, S, Armature Segments.

Armature, Ring.

An armature whose core is in the shape of a ring, as the Gramme Ring Armature. (See Figs. 23 & 27.)

49 STANDARD ELECTRICAL DICTIONARY.