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Q:How to test the fan noise? |
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A: Noise is measured in soundproof room with 16.8 dBA
maximum noise background. The sample fan is
positioned vertically by string fastened to
four corners of the fan. A microphone is placed
one meter away from the center of the fan
on the air intake side. |
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Q: What is the difference between ball bearing and
sleeve bearing? |
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A: Typically, the difference between ball bearing and
sleeve bearing is the life expectancy. On
average, a ball bearing fan will live 30,000
hours more than a sleeve bearing system. In
contrast to a sleeve bearing system, the ball
bearing system is relatively noisy to start
with compared to a sleeve bearing and tends
to get noisier over time. |
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Q: Does COOLTRON have value-added customization? |
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A: Yes, COOLTRON does do customization. It could be
as simple as specifying the lengths of the
lead wires, having thread inserts, and/or
adding a connector. We also offer modifications
to meet the specifications you require. For
example, it is possible to specify certain
criteria for the housing, increase a fan's
air pressure or air flow. |
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Q: What is the standard length of the lead wires? |
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A: The standard lead wire length is 12 inches or 304.8mm
for both DC and AC fans. However, we can always
modify it by extending or decreasing the length
to meet the customer's special need. |
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Q: What is the voltage for DC fans? |
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A: Depending on different sizes, DC fan voltage can
come in 5V, 12V, 24V and 48V. |
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Q: What is the voltage for AC fans? |
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A: Basically, AC fan can have 110V and 220V. Some AC
fans are rated dual voltage meaning they can
have both 110V and 220V in one fan. |
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Q: What is the material of DC fan housing and blade? |
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A: DC fan housing is made of plastic material UL 94V-0
and blade is made of P.B.T.+30% GF black. |
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Q: What is the operating temperature for DC fan? |
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A: For DC fan, the operating temperature is -10oC-70oC
at ordinary humidity level. However, as temperature
approaches 70oC, the heat may cause
deterioration to the fan's longevity. |
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Q: What is the operating temperature for AC fan? |
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A: For AC fan, the operating temperature is -20oC-85oC
at ordinary humidity level. However, as temperature
approaches 80oC, the heat may cause
deterioration to the fan's longevity. |
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Q: What is a Thermistor speed control (IC)? |
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A: Fans with this function offer a temperature sensor
that will detect the temperature and automatically
regulate the speed (RPM). As temperature rises
over time, the RPM also increases. |
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Q: What is an alarm (IC)? |
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A: An alarm can be applied to a fan to detect abnormalities.
For example, if an object interferes with
the performance of the fan, an output signal
will move to a higher voltage and start the
warning device. |
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Q: Can DC fan have terminal lead? |
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A: DC fans only come in wire leads but not terminal
leads. |
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Q: What is a speed sensor / tachometer (IC)? |
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A: A fan with this function has a pulse where speed
can be calculated and measured. Two complete
pulses are released for each revolution the
rotor produces. |
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Q: What is the Transistor with 3rd pulse wire? |
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A: Fan with a transistor and 3rd wire output. The output/signal
is a square wave voltage. It is continuously
sent through the 3rd wire as the fan is running.
With a 3rd wire, the fan can be attached to
a CPU cooler. A signal is then transmitted
to the motherboard. When this signal is not
received by the motherboard, the fan automatically
stops operating. |
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Q: Why does the DC line 120x120mm series have a built
in IC? |
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A: With a big size fan like the 120x120, more power
is required. In turn, there are more possibilities
for failure. Now, with an IC fans have an
auto-restart function to stop the fan from
failing. |
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Q: Why do fans with threaded inserts cost so much
more? |
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A: The process is done by ultra-sound. Due to a plastic
frame, while in production, there is 20% breakage
to the fan housing. That is, 2 fan housing
will break when 10 fan housing are being inserted
by threaded inserts. |
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Q: Does COOLTRON offer intelligent/smart fans? |
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A: COOLTRON adds a new level of product by offering
intelligent DC fans to meet the changing needs
of our customers. The speed on these fans
are regulated and operated according to temperature
level. Functions like tachometer, thermistor,
speed control, and different alarm versions
are all available. |
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Q: How many lead wires does a DC/AC fan have? |
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A: For fans with lead wires, the standard number of
wires is two. However, additional wires could
be added for special functions, like speed
sensor. |
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Q: Does COOLTRON have 48-volt fans for the telecommunication
industry? |
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A: Small applications like those in the telecommunication
industry require fans in a higher voltage.
In order to help this fast growing industry,
COOLTRON has kept up with the latest in technology
and offer the 48-volt fans in the 60x25mm,
80x25mm, 92x25mm, 120x25mm, 120x32mm, and
120x38mm series. |
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Q: Does COOLTRON have fans for harsh environment applications? |
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A: Our DC line offers the protection from water on all
dual ball fans. There are three levels of
waterproof protection; IP 55, powerful enough
to withstand pressure from water jets; IP
44 protects the fan from water splashes; and
IP 43, which protects against water shower
or high humidity environment. |
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Q: Are there different housing material for the fans? |
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A: Usually, AC fans (110V-220V) come in aluminum painted
housings; however, plastic can be requested
in replacement of the aluminum material. DC
line, on the other hand, comes in only plastic
(Customers may choose and pay for the cost
of a new mode if they choose to change the
housing). |
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Q: How to calculate MTTF? |
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A: MTTF Calculation |
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Assume that we tested FD2510B05W5 at 80oC and 50oC.
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200 test samples at 80oC |
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200 test samples at the same period |
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1008 hours tested |
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8,500RPM |
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0.09A current |
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Outcome |
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3 fans fail at 80oC test. 1 at
960th hour; 1 at 984th hour; and
1 at 1008th hour. And there was 1 fan failed
during 50oC test at 1008th hour. |
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Formula: A.F. = e (DH/K) x (1/273 + TL - 1/273 +TH)
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Where |
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A.F. is Acceleration Factor that is number of fan failed
at TL test divided by number of fan failed
at TH. |
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273 is absolute temperature |
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e is natural log |
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DH is Activation Energy |
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K is Bottzmann's Constant = 8.623x10-5 |
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TL is tested temperature low = 50oC |
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TH is tested temperature high = 80oC |
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Calculation |
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1.
Find out the DH: |
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Plug
in K= 8.623x10-5, TL =50oC, TH
=80oC. And, A.F. =3/1. |
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Thus,
3/1 = e (DH / 8.623x10-5) x (1/273+50 - 1/273+80) |
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So,
DH = 0.36 |
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Note:
DH is different from a fan manufacturer to
another and from time to time, since it is
related to the fan technology and quality
technology of the fan manufacturer. Somehow,
it is "know-how" of a fan manufacturer. |
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2.
Find out the total test hour at 80oC
(T): |
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The
total test hours at 80oC (T) |
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=
197 x 1008 + 960 +684 + 1008 = 201528 hours |
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3.
Find out the MTTF hours at 80oC
at 90% confidence level: |
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MTTF
hours at 90% confidence level = T/r, |
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Where
r is found from the GEM Table as "Attachment
B" r = 6.6808 |
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So,
MTTF at 80oC, at 90% confidence
level = 201528/6.6808 = 30165 hours |
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4.
Find out l (failure rate) at 80oC: |
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l
= 1/MTTF |
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l
= 1/30165 = 3.32 x 10-5 |
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5.
Then, we are able to find out MTTF hours at
other temperature level at 90% confidence
level. |
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For
example, now we want to find the MTTF hours
at 60oC at 90% confidence level: |
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60oC to 80oC A.F. =e(0.36/8.623 x 10-5)
x ( 1/273+60 - 1/273 + 80) |
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So,
now A.F. = 2.033 |
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Thus,
MTTF at 60oC = 30162 x 2.033 =
61325 hours |
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Furthermore, l = 1/61325 = 1.63 x 10-5 |
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Q: How to calculate fan life utilizing L10
method? |
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A: Minimum service life (L10 Life): |
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A:
Minimum service life (L10 Life): |
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T
(forecast) = T (actual) x FCC |
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Where: |
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T (forecast) = the forecasted L10 life under
working temperature Tf usually 25oC. |
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T (actual) = the actual tested life under
temperature Ta |
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FCC = temperature accelerator = 2 EXP[(Tf
- Ta)/10 ] |
