NonStop S-Series Planning and Configuration Guide (G06.25+)

Glossary
HP NonStop S-Series Planning and Configuration Guide—523303-015
Glossary-78
power factor correction
voltage waveform with respect to the current drawn by the load. When voltage and
current are in phase with each other, the power factor is unity, and the power for the
load is equal to the product of the applied voltage and load current (P=EI). When the
current waveform lags the voltage waveform, the load is inductive. Conversely, when
the current waveform leads the voltage waveform, the load is capacitive. In either case,
the power for the load is equal to the product of the applied voltage, load current, and
the angular displacement between the voltage and current waveforms (P=EIcosf).
Nonlinear (nonsinusoidal) loads also have a power factor. However, the power factor
for a nonsinusoidal load reflects harmonic content and not angular displacement.
power factor correction. The addition of a reactive component to offset the angular
displacement of a sinusoidal load. Traditionally, the normal power factor for a facility is
inductive, so the normal correction involves the addition of capacitors to offset the
lagging power factor. The capacitors offset part or all of the inductive reactance,
making the total circuit more nearly in phase with the applied voltage. The power factor
for nonlinear (nonsinusoidal) loads cannot be corrected through the addition of simple
reactive components. Harmonic filters are required to correct the power factor of
nonlinear loads.
power interface board (PIB). In system enclosures with power shelves, a board mounted
on the bulkhead located behind the power supplies in the power shelf. The PIB
provides electrical connection between the power supplies and DC power cables.
power monitor and control unit (PMCU). A field-replaceable unit (FRU) that connects the
batteries to the DC power distribution bus in an HP NonStop™ S-series enclosure and
provides a means of disconnecting the batteries for powering off the system. The
PMCU also provides a means for the service processor (SP) to diagnose the condition
of the batteries, fans, and power supplies; to regulate the voltage supplied to the fans;
and to provide the interface to the group ID switches and service light-emitting diodes
(LEDs). A group contains two PMCUs, one for each of the two DC power distribution
buses.
power shelf. In HP NonStop™ S7400, S7600, and Sxx000 processor enclosures and I/O
enclosures containing I/O multifunction (IOMF) 2 customer-replaceable units (CRUs),
an assembly residing below the chassis consisting of power supplies and supporting
circuitry that provides DC power to the enclosure.
power supply. (1) In system enclosures without power shelves, the component on the
processor multifunction (PMF) customer-replaceable unit (CRU) or the I/O
multifunction (IOMF) CRU that converts standard AC line voltage into the DC voltages
needed by the group components in the enclosure. (2) In system enclosures with
power shelves, the component located in the power shelf that converts standard AC
line voltage into DC voltage and delivers it to the PMF CRUs or IOMF CRUs in that
enclosure, which in turn supply the DC voltages needed by the group components in
the enclosure.
PPL. See process-pair list (PPL).