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RPM was measured two
ways: by a
Automation Direct TRD-S/SH Incremental Encoder which is
shaft driven from the motor.
The Digital electrical Output (one pulse per 360
degrees rotation) is conducted by a shielded cable to a
National Instruments USB 6259 Signal Processor.
The NI instrument connects to the computer via USB
cable.
The
RPM was verified with an optical pickup digital tachometer,
SSEPAI D2234a.
Calibration is considered unnecessary for these, as
their accuracy is measured in parts per million. At
all times, both RPM measuring instruments agreed to within
.1 RPM.
With the Torque and RPM measured, it was desired to
convert the output of the motor, first to horsepower.
RPM X Foot Pounds / 5252 = output in horsepower.
It was much more convenient to express the output in
Kilowatts, so the horsepower is multiplied by .746 to find
the output of the motor in KW.
Then, the electrical input must be measured in
Kilowatts also. Several
high accuracy meters were available for cross check accuracy
verification, and the one chosen to measure the electrical
input was a MASTECH MS 2203, serial 06022000109.
This instrument was new in the box, and was selected
for the following capabilities:
1)
It reads directly in True Kilowatts and Power
Factor
2)
It has an optically coupled RS232 output
to connect directly to the computer.
3)
It reads True KW, apparent power, volts,
amps, etc.
4)
Very high accuracy.
The
MASTECH was
directly connected to the computer.
In addition, a new AEMC OX7104C
was also attached to the motor and to the computer
network via an Ethernet cable.
The AEMC verified voltage, current, and phase angle,
which were compared to the directly attached MASTECH.
There were no noticeable deviations of readings.
Therefore, the following
high accuracy signals were fed to the computer, which logged
all three parameters:
1)
The digital signal representing torque in Foot
Pounds.
2)
The
timing pulse which the computer converted to True RPM’s
3)
The
digital signal representing True Power in Kilowatts.
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The
motor under test was loaded by two belt driven automotive
alternators, with load banks to dissipate the
electrical energy. (After
the first day, a second alternator and load bank was added
to more heavily load the motor under test)
Fans were added to cool the load banks after the
first test demonstrated that the load banks became extremely
hot. It was then
possible to vary the load on the motor, and the load could
be adjusted to a steady value.
Also,
there was a temperature sensor mounted inside the motor.
(This motor requires NO cooling and is sealed)
Temperatures of the motor under test averaged about
ten or twelve degrees above ambient, even after several
hours of testing.
It was noted that one could place their hand on the
motor under test and not feel any noticeable warming.
The load alternators, however, became very hot, too
hot to touch. This
provided further verification of the very high efficiency of
the motor under test compared to the conventional technology
of the alternators.
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Measured
Efficiency was plotted on the same graph as the calculated
efficiency. At
nearly every point, the actual measured efficiency equaled
or exceeded the calculated efficiency predicted by the
simulation program.
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