"A"
"B"
"C",
"D",
"E",
"F",
"G",
"H",
"I",
"J",
"K",
"L",
"M",
"N",
"O",
"P"
"Q",
"R",
"S",
"T",
"U",
"V",
"W",
"X",
"Y",
"Z"
Previous set of "P" terms in the Glossary.
POINT-CONTACT DIODE. A diode in which the end of a fine wire is pressed against a semiconductor.
Used as a detector or mixer over the microwave region.
POLAR RELAY. A dc relay in which the direction of
movement of the armature depends on the direction of the current flow.
POLARITY. The condition in an electrical circuit by which the direction of the flow of current can be
determined. Usually applied to batteries and other direct voltage sources. (2) Two opposite charges, one
positive and one negative. A quality of having two opposite magnetic poles, one north and the other
south.
POLE. The number of points at which current can enter a switch; for example, single pole, double pole,
and three pole. The sections of a field magnet where the flux lines are concentrated; also where
they enter and leave the magnet.
POLE PIECE. A piece of ferromagnetic material used to control the distribution of magnetic lines of
force; that is, it concentrates the lines of force in a particular place or evenly distributes the lines of
force over a wide area. The shaped magnetic material upon which the stator windings of motors
and generators are mounted or wound.
POLYPHASE. A term that describes systems or units of a system that are activated by or which generate
separate out-of-phase voltages. Typical polyphase systems are 2-phase and 3-phase; their voltages are
90- and 120-degrees out of phase, respectively. This term means the same as MULTIPHASE.
POSITION SENSOR. A component in a servosystem that measures position and converts the
measurement into a form convenient for transmission as a feedback signal. [Sensor Manufacturers]
POSITION SERVOSYSTEM. A servo-system whose end function is to control the position of the load it
is driving.
POSITIVE CLAMPER. A circuit that clamps the lower extremity of the output waveshape to a dc
potential of 0 volts.
POSITIVE FEEDBACK. Feedback in which the feedback signal is in phase with the input signal. Also
called REGENERATIVE FEEDBACK.
POSITIVE LOGIC. The form of logic in which the more positive logic level represents 1 and the more
negative level represents 0.
POSITIVE TEMPERATURE COEFFICIENT. The characteristic of a conductor in which the resistance
increases as temperature increases.
POTENTIAL ENERGY. Energy caused by the position of one body with respect to another body or to
the relative parts of the same body.
POTENTIOMETER. A variable resistor, used as a position sensor in servosystems, having a terminal
connected to each end of a resistive element and a third terminal connected to a wiper contact. The
output is a voltage that is variable depending upon the position of the wiper contact. The potentiometer
is commonly referred to as a variable voltage divider. It, in effect, converts mechanical information into
an electrical signal. Potentiometer Manufacturers
Next set of "P" Terms in the dictionary.
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