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RELIABILITY WIRE -
by www.ReliabilityDirect.com |
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Vibration, Balancing,
Alignment, Ultrasound, Oil Analysis & more...
Volume 6, Issue # 1
- February, 2005 |
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In This Issue |
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New
Products: Check
out the largest
e-catalog for Condition Monitoring
Ask The Expert: Infrared
Inspection of Motors
What's
Hot: Seriously
Cool tools for Less than $1,000.00!
Visit our
Suite of PdM
Websites:
Contest Winner: L.
Johnson -
The Collins Companies |
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New Products:
What's New at the Largest
e-Catalog for Condition Monitoring |
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HardChecker is the portable hardness tester of choice for industrial
settings. The microprocessor controlled unit operates on the LEEB rebound
principle providing an immediate readout of hardness in a variety of user
selectable scales.
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HFIR
IR Camera offers high resolution MB 320x240 FPA detector with Color,
Black and White, or Isotherm display. the HFIR offers features such as a
built in Color visual camera, built in microphone, 2.5" color multi
position LCD, interchangeable lenses, (both thermal and visual), removable
handle and easy to use image display controls - and now has on-board
digital storage .-
TMRT1Ex is an Intrinsically safe
multi-function laser and contact tachometer.
The TMRT1Ex has been tested and
certified according to the latest ATEX standards for use in intrinsic
safety zones generally found in industries such as the petrochemical, gas
and pharmaceutical among others-
TMMK 10-30 Combi-kit
is is designed for quick, safe,
mounting and dismounting of bearings with a bore diameter between 10 and
30 mm (0.4 - 1.2 in). For mounting, a multi-purpose fitting tool is
included which is suitable for bearings as well as bushings, seal rings,
belt pulleys and other similar products. For dismounting, a three-armed
puller is included. This puller can be used for deep groove ball bearings
with an interference fit on both rings or on the outer-ring without a
shaft.
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Ask The Expert:
Infrared Inspection of Motors
This
article is provided courtesy of
Snell Infrared,
a thermographic training company. |
| Most thermographers know the value of
inspecting motors with infrared, but not all are cross trained to
understand what to look for. |
| Of course you can perform a simple
check of the bearings, which typically should not run warmer than
the motor casing. Pillow block bearings are simple to compare with each
other. Vibration analysis should be used to confirm the thermal findings
of a suspect bearing. |
| You can also inspect the coupling. An
out of alignment condition will display a unique thermal pattern as the
associated mechanical forces are converted to heat. Again, correlate the
thermal data with vibration. |
| Abnormal friction on belts and gears
will also often display clear thermal patterns. Belts that are both too
tight and too loose can be seen thermally. But what else should
thermographers be looking at on the motor itself? |
| Jack Nicholas, a well known expert on
motor current analysis (MCrA), presented a paper at Thermal Solutions'97
the conference sponsored by the American Society for Nondestructive
Testing (ASNT), which clarifies a number of issues regarding motor
inspections. Nicholas, president of Maintenance Quality Systems
(410-729-1285), clearly outlines a dozen thermal signatures and
discusses their correlation with MCrA and vibration analysis. |
| He explains that motors are rated by
their maximum allowable operating temperature which is determined by the
type of electrical insulating materials used in the motor. Insulation
degrades rapidly when it exceeds its thermal rating. For every 10°C
(18°F) rise over their rating, anticipated motor life is reduced by 50%! |
| Ratings for motors are based by the
hottest spot allowed in the insulating system, which is inside the
motor, when the motor is operating in a 40°C (104°F) ambient
environment. Temperatures thermographers see on the outside of the motor
are usually 20°C (36°F) less than those on the inside. Thermographers
should be familiar with this information when checking motors: |
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Maximum Temperatures**
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| Class |
Internal |
External |
| A |
105°C/221°F |
85°C/185°F |
| B |
130°C/266°F |
110°C/230°F |
| F |
155°C/311°F |
135°C/275°F |
| H |
180°C/356°F |
160°C/320°F |
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**Maximum temperatures are based on 40°C (104°F)
ambient operating temperature.
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Nicholas goes on to discuss the thermal patterns associated with various
motor faults: n
AC motors a hot spot or uneven heating can indicate a resistive
imbalance, with the high resistance phase being cooler.
I n
DC motors excessive resistance, which can cause problems with torque
and speed controls, may be indicated by a hot spot.
An overall
temperature increase or uneven heating in an AC motor may result from
an inductive imbalance in
the stator due to a shorted coil.
Shorted
coils in an AC synchronous will have cooler poles on the rotor while
hotter poles are associated with damaged
pole laminations.
Uneven
heating between the speed control and the slip rings on an AC
induction motor may be caused by shorts
in the rotor coil.
Hot motor
leads may result from shorts in coils or loss of inductance in a DC
field or armature winding.
An overall
temperature increase or hot connective leads may result from cracked
rotor bars in a
squirrel cage inductive motor.
shorted
bars in a DC armature will appear warmer while open bars will ap pear
cooler.
dirt buildup inside a motor can cause an overall
increase in temperature.
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Of course Jack recommends using other technologies, especially motor
current analysis and vibration analysis, to verify findings. |
Link:
Infrared Cameras,
Vibration
Analyzers |
|
What's Hot:
Seriously Cool Tools for less than
$1,000.00 |
-
PT908 vibration meter
will measure acceleration, velocity and displacement in peak or RMS. It is
available with an internal accelerometer or external accelerometer with
magnetic base.
-
The
CO50 Carbon Monoxide Detector is pocket sized with audible and visual
alarms provide warning when CO safety levels are exceeded. The built-in
timer allows for ambient room CO monitoring applications, with the maximum
value recorded for the test period.
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EXTECH 381275 Handheld MultiScope
is a Graphical Storage Oscilloscope
and True RMS Multimeter Includes RS-232 Interface and PC Software -
$329.00
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Nova-Strobe DB Plus
is an all digital stroboscope is our best selling stroboscope. It remains
the standard for speed measurements and stop motion diagnostic inspection
for portable stroboscopes.
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EX-MP4 Intrinsically Safe IR Thermometer for non-contact temperature
measurement and monitoring of temperature processes in hazardous areas.
|
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Contest Winner: L.
Johnson -
The
Collins Companies |
|
November Question: The EXT-380268 Clamp on
Power analyzer data logger features
a
1000A
Clamp, measures 1 or 3 phase power to
600
kw. |
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Prize: Raytek
MT4 IR Thermometer
AND a spiffy
Reliability Direct Ball Cap! |
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The MicroVibe P Pocket PC Based Vibration Analyzer utilizes Multi-point
Automation™,
automatically collecting
acceleration, velocity, ____________ and
_________ ____________ simultaneously.
To enter the contest, send e-mail to
dgallagher@reliabilitydirect.com
with correct answers and contest in the subject line. |
|
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