Requirements for electric boilers.


Related Terms

DISTORTION

  1. Any undesired change in the waveform of an electric signal passing through a circuit or other transmission medium.
  2. In general, the extent to which a system fails to accurately reproduce the characteristics of an input signal at its output.
  3. Any undesired change in the waveform of a sound wave.

POOLE-FRENKEL EFFECT

An increase in the electrical conductivity of insulators and semiconductors in strong electric fields.

POLARIZABILITY

The electric dipole moment induced in a system, such as an atom or molecule, by an electric field of unit strength.

PLUGGING

1. Braking an electric motor by reversing its connections, so it tends to turn in the opposite direction; the circuit is opened automatically when the motor stops, so the motor does not actually reverse. 2. The formation of a barrier (plug) of solid material in a process flow system, such as a pipe or reactor.

PLANT FACTOR

The ratio of the average power load of an electric power plant to its rated capacity. Also known as capacity factor.

PLASMA TORCH

A torch in which temperatures as high as 50,000 C are achieved by injecting a plasma gas tangentially into an electric arc formed between electrodes in a chamber; the resulting vortex of hot gases emerges at very high speed through a hole in the negative electrode, to form a jet for welding, spraying of molten metal, and cutting of hard rock or hard metals.

PIEZOELECTRIC TRANSDUCER

A piezoelectric crystal used as a transducer, either to convert mechanical or acoustical signals to electric signals, as in a microphone, or vice versa, as in ultrasonic metal inspection.

PIEZOELECTRIC ELEMENT

A piezoelectric crystal used in an electric circuit, for example, as a transducer to convert mechanical or acoustical piezoelectric element piezoelectric gage signals to electric signals, or to control the frequency of a crystal oscillator.

PICKOFF

1. A device used to convert mechanical motion into a proportional electric signal. 2. A mechanical device for automatic removal of the finished part from a press die.

PHASE-COMPARISON RELAYING

A method of detecting faults in an electric power system in which signals are transmitted from each of two terminals every half cycle so that a continuous signal is received at an intermediate point if there is no fault between the terminals, while a periodic signal is received if there is a fault.

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