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Commonly used terms in the Electrical industry.
primary
(1) the source-side winding.
(2) refers to the portion of a nuclear power plant containing the reactor and its equipment. primary coolant the medium used to remove energy, in the form of heat, from a nuclear reactor core, e.g., water, helium, or liquid metal.
primary voltage
in power distribution the voltage at the primary winding of the distribution transformer.
primary winding
the transformer winding connected to the energy source.
prime mover
the system that provides the mechanical power input for a mechanical-to-electrical energy conversion system (generator), e.g., the diesel engine of an engine-generator set.
PSC motor
See
permanent split-capacitor motor
PT
potential transformer
See
voltage transformer
pull-in torque
the amount of torque needed to change a synchronous motor's operation from induction to synchronous when self-started.
pull-out torque
the maximum value of torque that an AC motor can deliver. An induction motor operating at the pull-out torque will operate at maximum slip, and loading it beyond the pull-out torque will cause the motor to stall. Synchronous motors remain at synchronous speed up to the pull-out torque. Exceeding the pull-out torque for a synchronous machine will lead to pole slipping and destruction of the machine.
pull-up torque
the minimum torque generated by an AC motor as the rotor accelerates from rest to the speed of breakdown torque. For an induction motor, this value usually is less than the locked-rotor torque, and thus establishes the maximum load that can be started.
pulse
a sudden change of an electrical value of short duration with a quick return to the original value. A pulse injects a short sharp burst of energy into a system and is usually quantified by its area rather than its amplitude or its duration. In the limit as the amplitude tends to infinity and the duration to zero, it approaches the Dirac delta function whose Laplace transform is unity.