To
increase the reliability
of the S.P.S., we
suggest users choose a
unit that has a rating
of 30% more power than
actual need. For
example, if the system
needs a 100W source, we
suggest that users
choose a S.P.S. with
130W of output power or
more. By doing this, you
can effectively boost
the reliability of the
S.P.S. in your system.
We
also need to consider
about ambient
temperature of the
S.P.S. and whether there
is additional device for
dissipating the heat. If
the S.P.S. is working in
a high temperature
environment, we need to
make some derating to
the output power. The
derating curve of
"ambient temperature"
versus "output power"
can be found on our spec
sheets.
Choosing functions based
on your application:
Protection function:
Over Voltage Protection
(OVP), Over Temperature
Protection (OVP), Over
Load Protection (OLP),
and etc.
Application function:
Signaling Function
(Power Good, Power
Fail), Remote Control,
Remote Sensing, and etc.
Special function: Power
Factor Correction (PFC),
Uninterruptible Power
Supply (UPS) function.
Make
sure that the model
qualifies for the safety
standards and EMC
regulations you need.
A2.
Can MEAN WELL's power supply be used in
the range of 45Hz ~ 440Hz? If YES, what
will happen?
Ans:
MEAN WELL's power supply
can be used within this
frequency range. But if
the frequency is too
low, the efficiency will
also be lower. For
example, when a
SP-200-24 is operated
under 230VAC and rated
load, if the frequency
of AC input is 60 Hz,
the efficiency is around
84%; however, if the
frequency of AC input
reduces to 50 Hz, the
efficiency will be
around 83.8%. If the
frequency is too high,
the power factor of the
S.P.S. with PFC (power
factor correction)
function will reduce and
this also will cause
higher leakage current.
For example, when a
SP-200-24 is operated
under 230VAC and rated
load, if the frequency
of AC input is 60 Hz,
the power factor is 0.93
and the leakage current
is around 0.7mA;
however, if the
frequency of AC input
increase to 440 Hz, the
power factor will
decrease to 0.75 and the
leakage current will
rise to around 4.3mA.
A3.
When testing a dual output power supply,
the +5V channel is correct, but the +12V
channel is over the specification.
What is going on?
Ans:
There are some
minimum-load
requirements on MEAN
WELL's multi-output
power supplies, please
refer to the
specification first
before connecting the
load. When the load
condition is 5V/4A,
12V/0A, the output
voltage of the 12V
channel will be around
12.8V that is over the
?% of voltage deviation
(12.72V) specified in
the spec. sheet. If we
add in the minimum load
0.2A to the 12V channel,
the 12V channel will
reduce to around 12.3V
which is within the
specification.
A4.
Why did the power supply shuts down
during operation and after turning it
off, I can restart the power supply
again?
Ans:
In
general there are two
circumstances that will
cause the power supply
to shut down. The first
one is the activation of
the over-load-protection
(OLP). To deal with this
situation, we suggest
increasing the rating of
the output power or
modifying the OLP point.
The second one is the
activation of
over-temperature
protection (OTP) when
the internal temperature
reaches the pre-set
value. All of these
conditions will let the
S.P.S. enter protection
mode and shut down.
After these conditions
are removed, the S.P.S.
will be back to normal.
A5.
Why the fan is not running after turning
on certain models?
Ans:
Some models control the
fan based on internal
temperature to extend
its life time. For
example, the Fan ON
temperature for the
S-240 series is ≧ 40C
(RT1). If the internal
temperature does not
reach the preset value,
the fan will remain
still until receiving
the start up signal.
A6.
What is "Inrush Current"? What will we
notice?
Ans:
At
input side, there will
be (1/2 ~1 cycle, ex.
1/120 ~ 1/60 seconds for
60 Hz AC source) large
pulse current (20~60A
based on the design of
S.P.S.) at the moment of
power on and then back
to normal rating. This
"Inrush Current" will
appear every time you
turn on the power.
Although it will not
damage the power supply,
we suggest not turning
the power supply ON/OFF
very quickly within a
short time. Besides, if
there are several power
supplies turning on at
the same time, the
dispatching system of AC
source may shut off and
go into protection mode
because of the huge
inrush current. It is
suggested that these
power supplies start up
one by one or use the
remote control function
of S.P.S. to turn them
on/off.
A7.
What is PFC?
Ans:
PFC
stands for Power Factor
Correction. The purpose
of PFC is to improve the
ratio of apparent power
and real power. The
power factor is only
0.4~0.6 in non-PFC
models. In PFC models,
the power factor can
reach above 0.95. The
calculation formulas are
as below:
Apparent Power=Input
Voltage x Input Current
(VA) Real Power=
Input Voltage x Input
Current x Power Factor
(W)
From the environment
friendly point, the
electric power plant
needs to generate a
power which is higher
than apparent power in
order to steadily
provide electricity to
the market. The real
usage of electricity
should be defined by
real power. Assuming the
power factor is 0.5, the
power plant needs to
produce more than 2VA to
satisfy 1W real power.
On the contrary, if the
power factor is 0.95,
the power plant only
needs to generate more
than 1.06VA to provide
1W real power need. It
will be more effective.
A8.
What is the difference between -V and
COM which are marked on the output side?
Ans:
COM
(COMMON) means common
ground. Please see
below: Single
output: Positive pole
(+V), Negative pole (-V)
Multiple output (Common
ground): Positive pole
(+V1, +V2,.), Negative
pole (COM)
A9.
In MEAN WELL's catalog, we see AC and DC
at input, what is it all about?
Ans:
Due
to different circuit
designs, MEAN WELL power
supply's input consists
of three types as
below:(√2VAC≒VDC)
a.85~264VAC;120~370VDC
b.176~264VAC;250~370VDC
c.85~132VAC/176~264VAC
by Switch; 250~370VDC
In a and b inputs
models, power supply
can work properly no
matter under AC or
DC input. Some
models need correct
connection of input
poles, positive pole
connects to AC/L;
negative pole
connects to AC/N.
Others may require
opposite connection,
positive pole to
AC/N; negative pole
to AC/L. If
customers make a
wrong connection,
the power supply
will not be broken.
You can just reverse
the input poles and
power supply will
still work.
In c input models,
please make sure
that you switch the
115/230V input
correctly. If the
switch is on the
115V side and the
real input is 230V,
the power supply
will be damaged.
A10.
What is MTBF? Is it distinct from Life
Cycle?
Ans:
MTBF and Life Cycle are
both indicators of
reliability. MEAN WELL
uses MIL-HDBK-217F as
the core of MTBF. An
expected reliability is
forecasted through
accounting component's
number (exclude fans).
The exact meaning of
MTBF is after
continuously using of
power supply in a
certain time, the
probability of operating
properly is 36.8%(e-1=0.368).
If power supply is
continuously used at
double the MTBF time,
the probability of
operating properly
becomes 13.5%(e-2=0.135).
Life Cycle is found
through using the
temperature rise of
electrolytic capacitor
to estimate the
approximate life of
power supply. For
example, SP-750-12
MTBF=769.3K hours;
electrolytic capacitor
C108 Life Cycle=202.2K
hours (Ta=45?C).
A11.
What is the fan control mechanism for SPS with cooling fan?
Ans:
Cooling fans have a relatively shorter lifetime
(typical MTTF, Mean Time To Failure, of around 5000-10000 hours)
as compared with other components of power supplies. As a result,
changing operating method of cooling fans can extend the operation
hours of the fans. The most common control methods are shown below:
Temperature control: if the internal temperature of a power supply
detected by a temperature sensor is over the set threshold, the fan will
start working at full speed, whereas, if the internal temperature is less
than the set threshold, the fan will stop working or at half speed. In
addition, cooling fans in some power supplies are controlled by a linear
control method whereby fan speed can be changed with different internal
temperatures synchronously.
Load control: if the loading of a power supply is over the set threshold,
the fan will start working at fullspeed, whereas, if the loading is less
than the set threshold, the fan will stop working or at half speed.
A12.
What is power good and power fail signals and how can use it?
Ans:
Some power supplies provide a "Power Good" signal when they are turned on, and send out a "
Power Fail" signal when they are turned off. This is usually
used for monitoring and controlling purpose.
Power Good: after the output of a power supply reaches 90%
rated voltage, an TTL signal (about 5V) will be sent out within
the next 10-500ms. Power Fail: before the output of a power supply is less than 90%
rated voltage, the power-good signal will be turned off at least 1ms in advance.
A13.
What is minimum load requirement and how can I read it from the spec?
Ans:
MW's multi- output power supplies, such as dual channels
or more, will have minimum load requirements. It is highly suggested
reading the spec before using them. For operating properly, each
channel must deliver a minimum current or the output voltages will
become unstable or be over the defined tolerance range. Minimum load
requirement can be seen on spec's "CURRENT RANGE" as the following
table shows:
CH1 requires a minimum current consumption of 2A, CH2 requires 0.5A,
CH3 requires 0.2A and CH4 requires 0.2A.
A14.
I have an TN-1500 inverter. Why the LED indication of AC IN is not lit after mains input has been
applied?
Ans:
According to the mains voltage of different countries, the output of TN-1500 inverter
110VAC version can be altered to 100/110/115/120VAC. In the same way, TN-1500
inverter 220VAC version can be changed to 200/220/230/240VAC as well. When the
inverter is set in UPS mode and the mains voltage fluctuates over ±15% of the set
AC output voltage, the inverter will shift its power source from the city power to
battery to remain the accuracy of the AC output Voltage. Meanwhile, the AC IN
indicator on the front panel of the inverter will be turned off.
B1.
How do we choose a power supply to
charge a battery?
Ans:
MEAN WELL has ESC, SC,
PA, PB series for
battery charger purpose
(120~360W). If these
series does not meet
customers' demands and
they like to choose a
power supply as a
charger, we advice to
pick up one which over
load protection (OLP)
mode is constant current
limiting. The models in
this mode provide
constant current even
when the protection
circuit is triggered.
The second
choice is fold-back
current limiting or
constant wattage model.
In this model, when a
battery is running low,
the output current of
the power supply will
gently increase. The
level of increase
depends on battery's
capacity and degree of
exhaustion. Hiccup
or shut down model are
not recommended because
it will stop to generate
current when OLP
happens.
B2.
If we need a 24V output power supply,
but MEANWELL does not have this model,
can we use two 12V power supplies
connecting in series instead of one 24V
power supply?
Ans:
YES, basically you can
do this to get the right
output voltage, but be
careful that the rated
output current of the
series system should be
the rating of the
minimum one in these
series connected power
supplies. Furthermore,
we like you to parallel
a diode at the output of
power supply to prevent
possible damage of
internal capacitors.
B3.
If we need a 600W output, can we use two
units of S-320 connected in parallel?
Ans:
No,
you can not do this
connection because S-320
is not equipped with the
parallel function. When
two power supplies are
connected in parallel,
the one with higher
output voltage will
share more loading and
deliver more (even
"all") power to the load
and cause these two
power supplies to be
unbalanced. We suggest
using PSP-300 or PSP-500
because it is equipped
with the current sharing
function.
B4.
Why I can not turn on the power supply
smoothly when the loads are motors,
light bulbs or capacitive loads?
Ans:
If
you connect the S.P.S.
to motors, light bulbs,
or high capacitive
loads, you will have a
high output surge
current when you turn on
the S.P.S. and this high
surge current will cause
failure of start up. We
suggest using S.P.S.
with constant current
limiting protection to
deal with these loads.
B5.
The output ground (GND) and frame ground
(FG) is the same point in my system, can
MEAN WELL's power supplies be used
in such system?
Ans:
Yes. Since our products
are designed based on
isolation concept, it
will be no problem that
the output ground (GND)
and frame ground (FG) is
the same point in your
system. But, EMI may be
affect by this
connection.
B6.
During the operation of MEAN WELL power
supply, there is some leakage current on
the case. Is this normal? Will
this leakage current hurt human body?
Ans:
Due
to the requirement of
EMI, there will be some
Y capacitors between
line and neutral to the
FG (case) to improve
EMC. These Y capacitors
will cause some leakage
current flow from line
or neutral to the case
(normally case will be
connected to earth
ground). For example,
IEC-60950-1 requires
that this current should
be less than 3.5mA for
IT equipment, so
basically the leakage
current you find on the
case will not hurt human
body. Proper connection
to Earth ground will
solve the leakage
current problem.
B7.
For certain need, is it possible to
reduce the noise of fan?
Ans:
Noise is directly
related to the fan which
is build into the power
supply. Lowering the
airflow of the fan means
reducing the heat
dissipation ability. It
will also influence the
reliability of the
products. Furthermore,
minimum airflow of fans
is defined by Safety
Organization and a
safety appendage will be
needed if using a new
fan. Generally, when we
choose a suitable power
supply, fan is not
necessary if wattage is
under 150W. Between
150~500W, both fan and
fanless products are
available. Above 500W, a
fan is needed.
B8.
What should be noticed when installing a
power supply in vertical and horizontal
directions?
Ans:
Most small wattage and
fanless power supplies
are mainly installed in
the horizontal position.
If you have to install
it vertically because of
mechanical limitation,
you should consider the
output derating due to
the heat concern. The
temperature derating
curve can be found on
the spec sheet.
Regarding the power
supplies with built-in
fan or the application
has forced cooling
system, vertical and
horizontal installations
have less difference.
Ex. In SP-150 derating
curve, the ambient
temperature difference
in application is 5
Celsius from vertical to
horizontal. The output
wattage in forced
cooling can be 20%
higher than air cooling
convection.
B9.
How to select a suitable proper circuit breaker or fuse for MW SPS?
Ans:
At input side, there will be a large transient inrush
current during the power on of an SPS. The inrush current is usually
of 20~70A based on the design of SPS, which will last for 1/2~1cycle
of AC input (ex. 1/120~1/60 seconds for 60Hz AC source). Every
breaker or fuse will actually have its own time-current (V-I)
characteristic curve. Users can choose a breaker or fuse which
has a rated current just over input current of SPS and check
whether the V-I curve of the breaker or fuse can withstand the
high inrush current from the SPS with a maximum duration of 1
cycle of AC input (e.g. 1/60 second).
B10.
Can MW charger use on Lithium battery or other type of battery?
Ans:
All MW chargers are designed for lead-acid batteries.
Every Lithium battery or other type of battery will have its
own charging/discharging characteristic. Modification will be
required for MW's charger in order to match the profile of
each battery or users' requirements. Please contact your local
distributor if you would like to have a modification for your
own battery.
C1.
Why the input voltage marked on the
spec. sheet is 88~264 VAC while the
label on the power supply says
that it is 100~240VAC?
Ans:
During safety
verification process,
the agency will use a
stricter standard --
?0%(IEC60950 uses +6%,
-10%) of the input
voltage range labeled on
the power supply to
conduct the test. So,
operating at the wider
input voltage range as
specified on the spec.
sheet should be fine.
The narrower range of
input voltage labeled on
the power supply is to
fulfill the test
standard of safety
regulation and make sure
that users insert input
voltage correctly.
C2.
Will MeanWell's products with CE marking
meet the EMC requirements after
assembling into my system?
Ans:
We
cannot guarantee 100%
that the final system
can still meet the EMC
requirements. The
location, wiring and
grounding of the
switching power supply
in the system may
influence its EMC
characteristics. In
different environment or
applications, the same
switching power supply
may have different
outcomes. Our test
results are based on
setup shown in the EMC
report.
C3.
What is different between information
(EN60950-1) and medical (EN60601-1)
safety standard?
Ans:
According to safety
standard, the leakage
current in EN60950-1
Class I cannot exceed
3.5mA; in EN60601-1
cannot exceed 0.3mA.
Others criteria like
safe distance and
numbers of fuse are also
different. Please
consult the diagram
below:
C4.
What is class 2, class II and LPS? What is the difference between class I and class II?
Ans:
Class I: Equipment where protection against electric shock is achieved
by using basic insulation and also providing a means of connecting
to the protective earth conductor in the building where by routing those conductive parts that are otherwise capable of assuming hazardous
voltages to earth ground if the basic insulation fails. This means
a class I SPS will provide a terminal/pin for earth ground connection.
Class II: Equipment in which protection against electric shock does not
rely on basic insulation only, but in which additional safety precautions,
such as double insulation or reinforced insulation are provided, there being no reliance on either protective earth or installation
conditions. This means a class II SPS does NOT have a terminal/pin
for earth ground connection.
LPS: When an electronic circuit is powered by a limit power source,
its output current and power are under the limitation shown in Table 3.4,
and the risk of fire can be reduced significantly. So, the safety distances and flammability rating of components can be much lower.
In this way, the design cost for SPS compliant with LPS can be reduced
as compared with non LPS SPS.
C5.
What is SELV? Are all MW SPSs compliant with SELV?
Ans:
This regulation applies to the secondary circuitry.
The circuit should be designed to guarantee that under
normal operating conditions, the voltage between any
two touchable points should be less than 42.4Vpeak or
60Vdc. For class I equipment, it refers to "between
any touchable point and the ground." Under single
fault conditions, the voltages between any two conductors
of the SELV circuit and between any one such conductor
and earth shall not exceed 42.4V peak or 60Vdc for a
period longer than 0.2 seconds. Moreover, a limit of
71V peak or 120Vdc shall not be exceeded.
According to requirements below, MW SPSs can comply with SELV.
IEC 60950-1 (ITE SPS): voltage of o/p circuit is less than 60Vdc under normal
condition.
IEC 61347-2-13 (LED SPS): voltage of o/p circuit is less than 120Vdc under
normal condition.
D1.
Will the monitoring software for TN-1500/3000 be enclosed in the packing box?
Ans:
The monitoring software for TN inverter will not be free of charge.
It can be purchased through your local distributor. The software will come within a package which includes a RJ-11 to RS-232 conversion cable. Please contact your local for detailed information.