GE Fuji Electric AF-300ES Instructions Manual page 126

Linear Acceleration/Deceleration: A circuit that controls the
rate at which the motor is allowed to accelerate to a set
speed or decelerate to zero speed. On most drives, this
circuit is adjustable and can be set to accommodate a par-
ticular application.
Locked-Rotor Current: Steady state current taken from the
line with the rotor at standstill (at rated voltage and fre-
quency). This is the current when starting the motor and
load.
Locked-Rotor Torque: The minimum torque that a motor will
develop at rest for all angular positions of the rotor (with
rated voltage applied at rated frequency).
Mechanical Safe Speed: Defined by the operating limits of
the driven equipment being controlled by the adjustable fre-
quency drive which should not be exceeded. The
manufacture's specification is to be followed carefully.
Megger Test: A test used to measure an insulation system's
resistance. This is usually measured in megohms and tested
by passing a high voltage at low current through the motor
windings and measuring the resistance of the various insu-
lation systems.
Negative Feedback: A condition where feedback is subtrac-
tive to the input reference signal. Negative feedback forms
the basis for automatic systems.
NEC: The National Electric Code is recommendations of the
National Fire Protection Association and is revised every
three years. City or state regulations may differ from code
regulations and take precedence over NEC rules.
NEMA: The National Electrical Manufacturers Association is
a non-profit organization organized and supported by manu-
facturers of electrical equipment and supplies. Some of
the standards NEMA specifies are: Hp ratings, speeds,
frame sizes and dimensions, torques and enclosures.
Open Loop: A control system that lacks feedback.
Operating/Service Deviation: A means of specifying the speed
regulating performance of a drive controller generally in per-
cent of base speed.
Operating Deviation defines speed change due to load
change and typically assumes:
1. A change from one steady state load value to another
(not transient).
2. A 95% maximum load change.
Service Deviation defines speed change due to changes in
ambient conditions greater than typical variations (Noted in
basic AFD unit's specification.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Overload Capacity: The ability of the drive to withstand cur-
rents beyond the systems continuous rating. It is normally
specified as a percentage of full load current for a specified
time period. Overload capacity is defined by NEMA as 150%
of rated full load current for one minute.
Overshoot: The amount that a controlled variable exceeds
desired value after a change of input.
Plugging: Plugging refers to a type of motor braking pro-
vided by reversing either line voltage polarity or phase se-
quence so that the motor develops a counter-torque which
exerts a retarding force to brake the motor.
PCC (Point of Common Coupling): Defined as the electrical
connecting point or interface between the utility distribution
system and the customer's or user's electrical distribution
system. The selection of the PCC within the system is of-
ten done by the utility.
Position Transducer: An electronic device (e.g. encoder or
resolver) that measures actual position and converts this
measurement into a feedback signal convenient for trans-
mission. This signal may then be used as an input to a
programmable controller which controls the parameters of
the positioning system.
Positive Feedback: Positive feedback is a condition where
the feedback is additive to the input signal. This generally
results in an unstable system.
Power: Work done per unit of time. Measured in horse-
power or watts:1 Hp = 33,000 ft-lbs. = 746 Watts.
Power Factor: A measurement of the time phase difference
between the voltage and current in an AC circuit. It is rep-
resented by the cosine of the angle of this phase differ-
ence. Power Factor is the ratio of Real Power (kW) to total
kVA or the ratio of actual power (W) to apparent power (volt-
amperes).
Displacement Power Factor: The displacement compo-
nent of power factor; the ratio of the active power of the
fundamental wave, in watts, to the apparent power of the
fundamental wave, in voltamperes.
Total Power Factor: The ratio of the total power input, in
watts, to the total voltampere input to the converter. The
power factor is determined at the ac line terminals of the
converter.
Distortion Factor: The ratio of the root-mean-square of
the harmonic content to the root-mean-square value of
the fundamental quantity, expressed as a percent of the
fundamental.
Preset Speed: Preset speed refers to one or more fixed
speeds at which the drive will operate.
11-4