SENSITIVITY-- (1) For an ammeter: the amount of
TOLERANCE-- (1) The maximum error or variation
current that will cause full-scale deflection of the
from the standard permissible in a measuring
meter. (2) For a voltmeter: the ratio of the
instrument. (2) A maximum electrical or
voltmeter resistance divided by the full-scale
mechanical variation from specifications that can
be tolerated without impairing the operation of
reading of the meter, expressed in
a device.
ohms-per-volt.
TRANSFORMER-- A device composed of two or
SERIES CIRCUIT--
An arrangement where
more coils, linked by magnetic lines of force,
electrical devices are
connected so that the total
used to transfer energy from one circuit to
current must flow
through all the devices;
another.
electrons have one
path to travel from the
negative terminal to
the positive terminal.
TRANSFORMER EFFICIENCY-- The ratio of
output power to input power, generally
SERIES PARALLEL CIRCUIT-- A circuit that
expressed as a percentage.
consists of both series and parallel
networks.
SINE WAVE-- The curve traced by the projection on
a uniform time scale of the end of a rotating
arm, or vector. Also known as a SINUSOIDAL
WAVE.
TRANSFORMER, STEP-DOWN-- A transformer so
constructed that the number of turns in
secondary winding is less than the number of
S O L E N O I D -- An electromagnetic device that
turns in the primary winding. This construction
changes electrical energy into mechanical
provides less voltage in the secondary circuit
motion; based upon the attraction of a movable
than in the primary circuit.
iron plunger to the core of an electromagnet.
T
TRANSFORMER STEP-UP-- A transformer so
constructed that the number of turns in the
secondary winding is more than the number of
THERMAL-MAGNETIC TRIP ELEMENT-- A
turns in the primary winding. This construction
single circuit breaker trip element that combines
provides more voltage in the secondary circuit
the action of a thermal and a magnetic trip
than in the primary circuit.
element.
TRIP-ELEMENT-- The part of a circuit breaker that
THERMOCOUPLE-- A junction of two dissimilar
senses any overload condition and causes the
metals that produces a voltage when heated.
circuit breaker to open the circuit.
THERMOCOUPLE METER MOVEMENT-- A
TRIP-FREE CIRCUIT BREAKER-- A circuit
meter movement that uses the current induced
breaker that will open a circuit even if the
in a thermocouple by the heating of a resistive
operating mechanism is held in the ON position.
element to measure the current in a circuit; used
to measure ac or dc.
TRUE POWER-- The power dissipated in the
resistance of the circuit, or the power actually
used to represent
THETA-- The Greek letter
used in the circuit.
phase angle.
TURN-- One complete loop of conductor about a
TIME CONSTANT-- (1) The time required to
core.
charge a capacitor to 63.2% maximum voltage
or discharge to 36.89% of its final voltage. (2)
TURNS RATIO-- The ratio of number of turns of
The time required for the current in an inductor
primary winding to the number of turns in the
to increase to 63.2% of maximum current of
secondary winding of a transformer.
decay to 36.8% of its final current.
AI-7
