18WuD2x

654 standard subroutine • state
standard subroutine A usually vendor-supplied
computer program segment applicable to more
than one program and used as needed as a subroutine.
standard temperature and pressure The condition
where the temperature is zero degrees Celsius
and the pressure is one atmosphere.
Abbreviated STP.
standard time Official civil time in a particular region.
See TIME ZONE.
standby 1. The state in which equipment is out of
operation, but can be immediately activated. Also
called IDLING. 2. A state of readiness on the part
of personnel, equipment, or systems.
standby battery An emergency power source for a
battery-powered installation.
standby current The CURRENT DRAIN of a circuit,
device, or system when in the standby condition.
standby equipment See EMERGENCY EQUIP-
MENT.
standby operation Keep-alive operation during a
standby interval (see STANDBY).
standby power The power drawn by an equipment
connected to the power supply, but out of operation.
standby power supply A circuit containing a battery,
an automatic switch, and sometimes a
power inverter. When utility power fails, the
switch actuates the supply, and the battery supplies
power to essential devices or systems. Similar
to an UNINTERRUPTIBLE POWER SUPPLY.
standing wave A stationary distribution of current
or voltage along a line because of the interactions
between a wave transmitted down the line and a
wave reflected back; it is characterized by maximum-amplitude
points (loops) and minimumamplitude
or zero points (nodes).
Voltage standing waves
Feed line
standing wave
standing-wave distortion Distortion of current or
voltage caused by standing waves on a transmission
line terminated in an impedance that contains
reactance, and/or that differs from the
characteristic impedance of the line.
standing-wave indicator 1. A device, such as a
lamp or meter, used to detect standing waves.
2. Standing-wave meter (see SWR BRIDGE).
standing-wave loss The additional loss, over the
matched-line loss, that occurs in a transmission
line when the standing-wave ratio (SWR) is not 1.
standing-wave meter See SWR BRIDGE.
standing-wave ratio Abbreviation, SWR. 1. The
ratio between the maximum and minimum voltage
along a transmission line. This quantity is
sometimes specifically called voltage standingwave
ratio (VSWR). 2. The ratio between the
maximum and minimum current along a
transmission line. 3. The ratio of load impedance
to feed-line characteristic impedance or vice
versa, whichever is greater than or equal to 1.
Ideally, the SWR is equal to 1 or 1:1, representing
a load impedance that is purely resistive and has
the same value as the characteristic impedance of
the feed line. A high standing-wave ratio causes
increased loss in the line and can also result in
excessive conductor heating or dielectric breakdown.
standoff insulator An insulator (usually of the
post type) that is used to hold a wire or component
away from a chassis or base.
star 1. In a gravity-battery cell, the copper electrode.
The name is derived from its star shape.
2. A star-shaped circuit of three-phase components.
Also see WYE CONNECTION.
star connection See WYE CONNECTION.
Stark effect The influence of a strong transverse
electric field on the spectrum lines of a gas.
starlight scope A device capable of viewing in apparent
total darkness. Its operation depends on
its ability to provide high amplification of extremely
low light levels, such as that of objects reflecting
the light from a moonless, but starlit, sky.
star rectifier See WYE RECTIFIER.
starter 1. An ignitor electrode in an ignitron (see
IGNITOR). 2. See STARTING BOX.
starting box A special rheostat for starting a motor
gradually in steps. The device is provided with an
electromagnet for holding the arm in the maximum-speed
position and releasing it when power
is interrupted.
starting rod An ignitor electrode in an ignitron (see
IGNITOR).
starting voltage 1. For a gas tube, the minimum
voltage that will initiate the glow discharge. 2. In
appropriate solid-state devices (e.g., a diac), the
voltage at which conduction between electrodes
occurs.
start lead The lead attached to the first turn of a coil.
Also called inside lead. Compare FINISH LEAD.
start/stop multivibrator See MONOSTABLE
MULTIVIBRATOR.
stat- A prefix denoting ELECTROSTATIC.
statampere The cgs electrostatic unit of current;
1 statampere = 3.335640 × 10 –10 ampere.
statcoulomb The cgs electrostatic unit of charge;
1 statcoulomb = 3.335640 × 10 –10 coulomb.
state 1. The present condition (i.e., on or off, true
or false, 1 or 0, high or low) of a bistable device,
such as a flip-flop. 2. The physical or electrial
condition or status of a component, device,
circuit, or system.