Archive for the 'D-Damper' Category

Jan-5th-2009

Dead Wire

(a) The percentage or portion of wire on a dynamo or motor armature that
does not concur in the production of electromotive force. The
dead-turns, q. v., of a drum armature or the inside wire in a Gramme
ring armature are dead wire.
(b) A disused and abandoned electric conductor, such as a telegraph
wire.
(c) A wire in use, but [...]

Jan-5th-2009

Dead-Turns

In the winding of an armature, a given percentage of the turns, it may
be 80 per cent., more or less, is assumed to be active; the other 20 per
cent. or thereabouts, is called dead-turns. This portion represents the
wire on such portions of the armature as comes virtually outside of the
magnetic field. They are termed dead, [...]

Jan-5th-2009

Dead Point of an Alternator

A two-phase alternator of the ordinary type connected as a motor to
another alternator cannot start itself, as it has dead points where the
relations and polarity of field and armature are such that there is no
torque or turning power.

Jan-5th-2009

Dead Earth

A fault in a telegraph line which consists in the wire being thoroughly
grounded or connected to the earth.

Jan-5th-2009

Dead Beat. adj

Reaching its reading quickly; applied to instruments having a moving
indicator, which normally would oscillate back and forth a number of
times before reaching its reading were it not prevented by damping.

Jan-5th-2009

Dash-Pot

A cylinder and piston, the latter loosely fitting or perforated, or some
equivalent means being provided to permit movement. The cylinder may
contain a liquid such as glycerine, or air only. Thus the piston is
perfectly free to move, but any oscillations are damped.
In some arc lamps the carbon holder is connected to a dash-pot to check
too sudden [...]

Jan-5th-2009

Damping

Preventing the indicator of an instrument from oscillating in virtue of
its own inertia or elasticity. In a galvanometer it is defined as
resistance to quick vibrations of the needle, in consequence of which it
is rapidly brought to rest when deflected (Ayrton). In dead-beat
galvanometers damping is desirable in
order to bring the needle to rest quickly; in ballistic [...]

Jan-5th-2009

Damper

(a) A copper frame on which the wire in a galvanometer is sometimes
coiled, which acts to damp the oscillations of the needle.
(b) A tube of brass or copper placed between the primary and secondary
coils of an induction coil. It cuts off induction and diminishes the
current and potential of the secondary circuit. On pulling it out, [...]

Recent Comments

Video