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Electrical input
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Voltage
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This data tells
you at which voltage the motor is made to operate. Nameplate-defined
parameters for the motor such as power factor, efficiency, torque and current
are at rated voltage and frequency. When the motor is used at other voltages
than the voltage indicated on the nameplate, its performance will be
affected.
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Frequency
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Usually for motors,
the input frequency is 50 or 60 Hz. If more than one frequency is marked on
the nameplate, then other parameters that will differ at different input
frequencies have to be indicated on the nameplate as well.
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Phase
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This parameter
represents the number of AC power lines that supply the motor. Single-phase
and three-phase are considered as the standard.
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Current
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Current indicated
on the nameplate corresponds to the rated power output together with voltage
and frequency. Current may deviate from the nameplate amperes if the phases
are unbalanced or if the voltage turns out to be lower than indicated.
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Type
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Some manufacturers
use type to define the motor as single-phase or poly-phase, single-phase or
multi-speed or by type of construction. Nevertheless, there are no industry
standards for type.
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Power factor
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Power factor is
indicated on the nameplate as either “PF” or “P .F” or cos f . Power factor
is an expression of the ratio of active power (W) to apparent power (VA)
expressed as a percentage. Numerically expressed, power factor is equal to
cosine of the angle of lag of the input current with respect to its voltage.
The motor’s
nameplate provides you with the power factor for the motor at full-load.
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Mechanical Input
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kW or horsepower
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kW or horsepower
(HP) is an expression of the motor’s mechanical output rating – that is it’s
ability to deliver the torque needed for the load at rated speed
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Full-load speed
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Full-load speed is
the speed at which rated full-load torque is delivered at rated power output.
Normally, the full-load speed is given in RPM. This speed is sometimes called
slip-speed or actual rotor speed
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Performance
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Efficiency
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Efficiency is the
motor’s output power divided by its input power multiplied by 100. Efficiency
is expressed as a percentage. Efficiency is guaranteed by the manufacturer to
be within a certain tolerance band, which varies depending on the design
standard, eg IEC or NEMA.
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Duty
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This parameter
defines the length of time during which the motor can carry its nameplate
rating safely. In many cases, the motor can do it continuously, which is
indicated by an S1 or “Cont” on the nameplate. If nothing is indicated on the
nameplate, the motor is designed for duty cycle S1.
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Reliability
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Insulation class
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Insulation class
(INSUL CLASS) is an expression of the standard classification of the thermal
tolerance of the motor winding. Insulation class is a letter designation such
as “B”or “F”, depending on the winding’s ability to survive a given operating
temperature for a given life. The farther in the alphabet, the better the
performance.
For instance, a
class “F” insulation has a longer nominal life at a given operating
temperature than a class “B”.
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Maximum ambient
temperature
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The maximum ambient
temperature at which a motor can operate is sometimes indicated on the
nameplate. If not the maximum is 40°C for EFF2 motors and normally 60°C for
EFF1 motors. The motor can run and still be within the tolerance of the
insulation class at the maximum rated temperature.
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Altitude
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This indication
shows the maximum height above sea level at which the motor will remain
within its design temperature rise, meeting all other nameplate data.
If the altitude is
not indicated on the nameplate, the maximum height above sea is 1000 metres.
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Construction
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Enclosure
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Enclosure classifies
a motor as to its degree of protection from its environment and its method of
cooling. Enclosure is shown as IP or ENCL on the nameplate
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Frame
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The frame size data
on the nameplate is an important piece of information. It determines mounting
dimensions such as the foot hole mounting pattern and the shaft height. The
frame size is often a part of the type designation which can be difficult to
interpret because special shaft or mounting configurations are used
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Bearings
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Bearings are the
component in an AC motor that requires the most maintenance. The information
is usually given for both the drive-end (DE) bearing and the bearing opposite
the drive-end, non drive- end (NDE).
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