MIL-STD-704F
during the electric starting of propulsion engines and the battery start of an auxiliary power unit. Normal operation includes switching of utilization equipment, prime mover speed changes, synchronizing and paralleling of power sources, and operation from external power sources.
Transfer operation, as defined herein, is a normal function. It is treated separately in this standard because of the power interruption that it may produce.
Conducted switching spikes, which are excursions of the instantaneous voltage not exceeding 50 microseconds, are normal operation characteristics.
3.19 Overfrequency and underfrequency. Overfrequency and underfrequency are those frequencies that exceed the limits for normal operation and are limited by the action of protective devices.
3.20 Overvoltage and undervoltage. Overvoltage and undervoltage are those voltages that exceed the limits for normal operation and are limited by the action of protective devices.
3.21 Point of regulation. The POR is that point at which a power generation source senses and regulates the system voltage. The POR should be at the input terminals of the line contactor connecting the power source to the load bus.
3.22 Power factor. The ratio of real power (measured in watts) to apparent power
(measured in volt-amperes).
3.23 Pulsed load. Pulsed loads are loads whose power requirement varies under steady state conditions because of underlying physical phenomena or the inherent operating mode of equipment.
3.24 Rate of change of frequency. The rate of change of frequency is defined as the ratio of the absolute difference in frequency over a designated period of time to the designated period of time. The unit of rate of change of frequency is designated Hertz per second (Hz/s).
3.25 Ripple. Ripple is the variation of voltage about the steady state DC voltage during steady state electric system operation. Sources of ripple may include, but are not limited to, voltage regulation instability of the DC power source, commutation/rectification within the DC power source, and load variations within utilization equipment.
Ripple amplitude is the maximum absolute value of the difference between the steady state and the instantaneous DC voltage.
3.26 Steady state. Steady state is that condition in which the characteristics remain within the limits for normal operation steady state characteristics throughout an arbitrarily long period of time. Steady state conditions may include lesser transients.
3.27 Transfer operation. Transfer operation occurs when the electric system transfers between power sources, including transfers from or to external power sources.
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