Major Characteristics for Medical Power Supply

Medical environments are known for its omnipresent risk for both vulnerable and healthy people. To ensure the utmost safety, the design of Medical Power Supplies is monitored by the strictest quality exigences and safety regulations.

As the heart of any electrical medical device, the medical power supplies must comply with the highest standards of performance, safety (IEC 60601) and reliability. Criteria such as MOPP, MOOP, low leakage current, EMC must be taken into consideration during the development stage.

As a result, Medical Power Supplies are equipped with higher levels of insulation and superior EMC performance, and we can distinguish one medically approved Power Supply from other electronics components by its exigent protection level, its high reliability and its extended life cycle of components.

How to choose your Medical Power Supply?

As the keystone of one medical system, it is extremely important to select a safe and reliable Medical Power Supply. To choose the most suitable Medical Power Supply for the Medical system, the R&D engineers are strongly suggested to take, as guideline of selection, the listed criteria below into consideration


A. Electrical requirements


The input voltage range and required power should be defined for the application, as well as its output voltage and the needed current to power the application:

  • Input voltage range:  the most common input source is an AC source, and the range requirement is related to the destined market of the end devices. In the case of multiple market regions of the Medical system, it is strongly recommended to choose a Medical Power Supply with input voltage range covering at least the range of 100VAC to 240VAC.
  • Power requirement:  the required power depends mainly on the end device. It is suggested to keep in mind the derating caused by the unfavorable working temperature, as well as the potential peak current.

Output voltage and current:  according to the design of the Medical system, some systems demand a constant current output while others need constant voltage. The R&D engineers should choose an adequate Medical Power Supply, with the right level and type of DC output, based on the design of the application.


B. Regulations


As each market territory and each application field imposes its own safety regulations on the end devices, it is crucial to understand which certifications are mandatory for the application and its target market(s) during the development process.

For instance, home healthcare devices are required to meet the standards of IEC 60601-1-11, while for equipment not directly in contact with the patient, IEC 62368 might still give one the possibility to get a medical certification for medical test and measurement equipment on a system level.

Meanwhile, each country adopts its specific safety standards for the application field (e.g. UL ANSI/AAMI ES60601-1 for the US, EN 60601-1 for EU countries, CAN/CSA-C22 3rd edition for Canada…etc.


C. Installation Method


The installation of the PSU can be either internally or externally depending on how the Power Supply is designed to be integrated into the system.

External solution:

Internal solution:

  • Medical Enclosed type: PSU with plastic or metal case.
  • Medical PCB type: A PCB populated with components which from the power supply. Normally this solution is without any mechanical protection such as a housing. For this reason, normally installed inside an application and not touchable by the user.
  • Medical On board or Medical PCB mount: PSU designed to fit on a PCB. It can be either “open frame” or “encapsulated”. The second type is potted with compound to provide protection against external elements (e.g. moisture, corrosive elements, shock, vibration…etc.).


D. Other requirements


Medical systems are regulated with extremely vigorous exigences. On top of the above criteria, it is also important to verify that the other specific requirements are met:

  • Class: Class I or class II
  • Heat dissipation: Forced air cooling (with fan) or Passive cooling (without fan)
  • Level of protection required:  2 x MOOP, 2 x MOPP
  • Leakage current
  • Overload protection: Constant Current Limiting or Hiccup mode
  • Remote on/off function
  • Current sharing function
  • Parallel function

More Information about Medical products?

Specific Requirements for Medical Power Supplies

I. IEC 60601-1:


Defined by the world known International Electrotechnical Commission (IEC), IEC 60601-1 is a series of technical standards destined to ensure the safety and performance of electrical equipment in the medical industry. On one hand, some digression from the IEC 60601-1 standards exists. For example, EN 60601-1 for Europe and ES 60601-1 for the US market which are harmonized with the IEC standards. One the other hand, there are also some “collateral” standards to IEC 60601-1; such as IEC 60601-1-2 which is the 4th edition of collateral EMC standards to IEC 60601-1.




In the medical environment, risk is constantly present for patient and/or operator of a medical device. Aiming to protect both groups from electrical medical devices, MOOP and MOPP are introduced to monitor the level of insulation.

  • MOOP stands for Means of Operator Protection. This category is related to electronic devices which are handled by trained operators, and do not come into direct contact with the patient. The medical device with 2 x MOOP has an isolation of 3000V AC isolation.
  • MOPP, on the other hand, is the Means of Patient Protection; all electronic devices with direct physical contact with patients must meet stricter standards and require a double isolation between input and output.

Presuming that patients are vulnerable; MOPP standards are specially designed to protect them from any potential electric shock. In the design, MOPP requires the medical devices to have two separate insulation barriers.

Therefore, devices are MOOP and MOPP classified depending on the type of contact with patients and operators.

Classification Required Isolation Required Creepage Requirement Insulation
MOOP 1500V AC 2.5mm
2 x MOOP 3000V AC 5mm Reinforced
MOPP 1500V AC 5mm
2 x MOPP 4000V AC 8mm Reinforced

1 MOOP and MOPP under IEC60601-1 are different in the levels of isolation, creepage, insulation.

III. Low leakage current


The essential use of medical equipment is on the human body, therefore the chance and duration of contact with this equipment is higher and longer. Having electric current running throughout the body can be extremely dangerous and might even result in death. For example, a current as low as 40mA could already be fatal to a healthy person, while a weakened person’s tolerance is even lower.

To protect all people in contact with the devices from the electric shock, medical power supplies must meet strict requirements in terms of leakage current. While Applied Parts (AP) indicate the parts of a Medical device or a Medical system which, during normal use, come into direct physical contact with a patient. The standards of IEC60601-1 give a clear definition of the acceptable values of leakage current for each classification of Applied Parts (AP), and the classifications are further divided into 2 categories: “NC” for normal condition and “SFC” for Single fault condition.

Leakage Current
Type B Type BF Type CF
Earth Leakage Current 5mA 10mA 5mA 10mA 5mA 10mA
Enclosure Leakage Current 100µA 500µA 100µA 500µA 100µA 500µA
Patient Leakage Current 100µA 500µA 100µA 500µA 10µA 50µA

2 Different Leakage Current limits defined by IEC60601-1 according to the medical environment: Type B, Type BF, Type CF

IV. Classification of medical environment


Just like medical power supplies, end systems in medical environments are also regulated by strict isolation and leakage current requirements.

Depending on the type of physical contact between patient and medical device, there are three main classification types of Applied Parts (AP) in the medical environment: Type B, Type BF, Type CF.

  • Type B (Body)
    Devices with no direct physical contact with patients. Examples: medical bed, medical laser…etc.
  • Type BF (Body Float)
    Devices with physical contact with patients and might present risk in the case of device failure. Examples: Incubators, diagnostic equipment, etc.
  • Type CF (Cardiac Float)
    Direct contact to the patient’s heart, risk of injury or death in the event of device failure. Examples: Defibrillators, heart-lung machines, etc.

Note: Medical power supplies for type BF & CF devices are designed to meet 2 x MOPP

V. EMC standard and limits


Malfunction induced by electromagnetic or interference could be fatal when it comes to life-saving devices. The EMC standards EN 55011 for electromagnetic interference and IEC 60601-1-2 with reference and electromagnetic immunity must be considered.

The 4th edition of the IEC-60601-1 standard on EMC is much more vigorous with electromagnetic immunity than the previous edition. Medical devices must now be immune to HF fields up to 2.7GHz, which represent an increase by 0.2GHz. To prevent damage caused by electrostatic discharge, the limits have also been increased accordingly. For contact discharge, the level has been increased from 6 to 8kV. For air discharge, it has been increased from 8 to 15kV compared to the previous edition.


VI. EU Medical Device regulation (MDR)


The European Union Medical Device Regulation (MDR) published 2017, will soon replace the current Medical Device Directive (MDD) (93/42/EEC) and the EU’s Directive on active implantable medical devices (90/385/EEC). All development engineers and manufacturers related to Medical Devices within Europe will need to follow the Medical Device Regulation of 2017 published by European Parliament.


VII. ISO 13485


ISO 13485 is the standard for the quality management system for medical devices. The requirements are destined to organizations involved in the design, production, storage, installation and maintenance of medical devices and other related services.

Got questions?

Look at the section below to find the most frequently asked questions (with answers)
we received in Medical Power Applications.

A Surge Protection Device is optimized for a single voltage. Therefore, SPD should be chosen according to the actual operating voltage of the part that need to be protected.Secondly, the voltage protection level shows what is the maximum voltage appeared at output side when a specified surge is coming to the SPD. In general, the lower the voltage protection level, and the higher the discharge or surge current from SPD, means the better protection that the SPD provides.

Enclosed power supplies:

  • 35-125W applications: The RD, RT and RQ series provide dual, triple, and quadruple output.
  • 150-320W applications: The QP series comes with 4 different outputs.
  • 190-240W applications: The semi-potted HDP series provides dual output.

PCB-type power supplies:

  • 25-250W applications: The PD and PT series provide dual and triple output.
  • 45-200W medical applications: The MPD, MPT and MPQ series offer dual, triple, and quadruple output.

Configurable power supplies:

  • 400W fanless, the UMP-400 series is a convection cooled 1U height modular power supply and can provide up to 4 different outputs.
  • 450-1000W for ITE applications, MP series provides up to 7 different isolated outputs.
  • 650-1200W for ITE and medical applications, NMP series can provide up to 6 different isolated outputs with the NMS single output modules from 3~55VDC. With the NMD dual output module more outputs are possible in the 3~30VDC range. Additionally, the NMP offers a 5V AUX output.

Please also see our “NMP Page

Desktop-type power supplies:

  • 25-50W applications, our GP series is a triple-output type industrial adaptor. 

DC-DC modules:

  • 1-2W applications, the SMD-type DETN series comes with +/-5, 12 or 15V symmetrical outputs.
  • 3-30W applications, the DIP-type DCW, DCWN, RDDW, DKM, DKMW, DKA30 series come with +/- 5, 12 or 15V symmetrical outputs.
  • 20W ultra-wide input range requirements, the DIP-type RDDW20UW series can provide a +/-12, 15 and 24V symmetrical output.
  • 15W applications, the DIP-type DKE15 series offers a +/-5, 12, 15 or 24V symmetrical output.
  • 30W applications, the DIP-type TKA30 series offers a 5V output in addition to a +/-12 or 15V symmetrical output.
  • 10-15W applications, the on-board-type NSD series can provide a +/- 5, 12 or 15V symmetrical output.
Categories: Industrial, Medical, Others

The number of outputs, the available output voltage range and minimum load requirements are some key aspects to be considered when it comes to choosing a multiple output type PSU.

Basic power supplies in this category have a so-called minimum load requirement. These types of PSU rely on one same internal transformer to provide different outputs. For all outputs to work properly, a minimum current should always be drawn from the main output channel.

See below example how this is shown in the specification for the RPT-60A

More advanced power supplies such as the RT-65A do not have this restriction:

There are two options to select a multiple output PSU: a standard PSU with fixed output voltages, or modular power supplies. Modular PSUs can be personalized according to one’s systems requirements and offer much more flexibility than fixed output voltages PSUs. For instance, our NMP modular medical power supply series come with up to 6 slots for different output voltages from 3 to 55V which can be connected in series and parallel to adapt to each application.

Categories: Industrial, Medical, Others

All MEAN WELL power supplies come with at least one fuse on the line path1. The internal fuse is designed to handle the nominal current on the whole range of input voltages; for the same power, at low input voltages, the current drawn by the PSU will be higher:

LPV-100 input ratings (internal T 4AL-250VAC fuse)

If you want a more adapted protection for a specific input voltage, you could add an external fuse to protect the power supply. Considering that it will only protect the PSU (no other appliances connected after it), you should refer to the datasheet of the power supply and look for the typical input current under your input voltage. The fuse should be rated slightly higher than this current value. The selected external fuse should be a Slow-Blow type, this to avoid it is triggered by the inrush current of the power supply. For reference, most of MEAN WELL power supplies use type-T slow acting fuses. 

Further please take into consideration that fuses characteristics are given for an operating temperature of 25oC. Exceeding this value will lower the current rating and shorten its lifetime. Similarly, when operated in cold areas, the current rating will be increased.

Note 1: Except for DDRH-60 series

Categories: Industrial, Medical, Others

Find the latest news in the MEAN WELL APP

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MEAN WELL’s distributor information can be found on Distributor Network-MEAN WELL Switching Power Supply Manufacturer 

  1. Click on the region that you are located
  2. Select the country you are in
  3. Click on the search button
  4. Scroll down to see our local distribution channels
  5. Look for the distributor with a tick for the product group that you are looking for

MEAN WELL has the largest distribution network for serving your small and medium demand Power Supplies. You can find all MEAN WELL’s distribution channels on Distributor Network-MEAN WELL Switching Power Supply Manufacturer

OEM’s which have no sales channel for MEAN WELL products yet can contact us via the “Contact Us” form on this website.

MEAN WELL’s discontinued product schedule and End of Life products are normally updated 2 times per year, in January and in July and are published on See FAQ “Where can I find MEAN WELL’s discontinued product schedule and End of Life information?

The normal procedure for E.O.L. is:

  1. The product or series is announced in the Discontinued product list in January or July and announced as NRND (Not Recommend for New Design) 
  2. 6 months later the lead time of the product or series will increase +30 days, the price will increase as well.
  3. Another 6 months later, the lead time will increase another +30 days (so + 60day compared to the original lead time), the price will increase again.
  4. Another 6 months later, the lead time will increase another +30day (so +90 days compared to the original lead time) and the price will increase again and additionally there will be a MOQ of 200pcs (and steps of 100 for higher quantities)
  5. After another 6 months the last buy is announced on the website. This will be the last opportunity to place an order for this product or series.

In total MEAN WELL’s End of Life, procedure will take 2 years. However, there are situations for instance that certification is expired, or some components can no longer be obtained by the market which will force to accelerate the EOL schedule. Therefore, it is always highly recommended from the moment that a product is on the discontinued list to design in one of our new generation products. If need any advice to this, please use the “Contact Us” function on this website.

MEAN WELL’s discontinued product schedule and End of Life products are normally updated 2 times per year, in January and in July. To see the full list, go to

1. Click on products

2. Click on Discontinued products for the schedule for the EOL schedule 

Click on EOL for the MEAN WELL products which are End Of Life

You can use the “Contact Us” function on this website

MEAN WELL’s website provides you all the basic information about our Power Supplies. This includes company news, product announcements, ISO certificates, Specifications, test report, Certificates, ROHS declarations, Reach declarations and many more.

MEAN WELL’s products can be found on

1. Click on products and select the product category

Or in case you already have a part number, you can use the search function on the website:

2. Use the search function on the website to find the right product

3. Fill in the series number in the search field (do not include the last extensions such as -12 in XLG-150-12)

4. Click the search button 

5. Click on the PDF icon to open the specification

Noise is directly related to the fan which is built 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. If fan noise is a critical concern, we suggest to select FANLESS products or contact MEAN WELL for other possibilities according to the conditions of use.

Categories: Industrial, Medical, Others
Tags: Fanless, Noise

There are two different applications when power supplies are connected in series. One is to generate plus minus voltage, another is to increase total output voltage. Connection methods are as follows:

(1) Connection for plus and minus voltage are shown as follow

(2) To increase the total output voltage (Output current remain the same). Diodes connect in parallel at output side of the driver is necessary to prevent damage during start up. The voltage rating of diode shall greater than V1 + V2(shown as figure below), in addition, peak forward surge current rating shall greater than rated current.

* Because part of the signal ground is shorted with output ground, strongly suggest to use isolated signals to achieve control scheme, in order to prevent damage to the product.

Categories: Industrial, Medical, Others

An adaptor may need connection of a power cord to receive energy needed from the utility. You can refer to the specification of the adaptor for the connector (AC inlet) at the adaptor end of the power cord; Different countries/regions vary in type of AC socket and voltage, please look at the table below for the information of the AC plug you need.

Categories: Industrial, Medical, Others

It is the small unwanted residual periodic variation of the direct current (DC) output of a power supply which has been derived from an alternating current (AC) source. The wave form is shown as figure below.

There are two AC contents, also known as Ripple and Noise (R&N), on the DC output. The first one, coming from sine wave rectification, is at a low frequency which is 2 times of the input frequency; the second one is at high frequency which is from the switching frequency. For measuring high frequency noise, a configuration of an oscilloscope with a bandwidth of 20MHz, a scope probe with shortest ground wire possible, and add 0.1uF and 47uF capacitors in parallel with test point for filtering out noise interference are required.

Categories: Industrial, Medical, Others

1. To increase the reliability of the power supply, 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 power supply with 130W of output power or more. By doing this, you can effectively boost the reliability of the power supply in your system.

2. We also need to consider about ambient temperature of the power supply and whether there is additional device for dissipating the heat. If the power supply 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 specifications.

3. Choosing functions based on your application:

  • Protection function: Over Voltage Protection (OVP), Over Temperature Protection (OVP), Overload 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.

4. Make sure that the model qualifies for the safety standards and EMC regulations you need.

Categories: Industrial, Medical, Others

All MEAN WELL power supplies have an internal fuse except for the DDRH series.

Categories: Industrial, Medical, Others
Tag: Fuse

MEAN WELL’s Step files/ 3D files can be found on

  1. Use the search function on the website to find the right product
  2. Fill in the series number in the search field (do not include the last extensions such as -12 in XLG-150-12)
  3. Click the search button 
  4. Click on the PDF icon to open the specification
  1. Click on 3D OUTLINE
  2. Click on the model XLG-150-3D to download the step file.

Capacitive loads can be found under many different forms: capacitor banks, batteries, and even power supplies themselves are considered as capacitive loads. The principal issue that can appear on such type of load is at PSU start-up: a discharged capacitor basically acts like a short-circuit at start-up, hence it may overload the output.

One solution is either to add current limiting resistors in series with the capacitive load to limit the output current, or to select a power supply with “constant current limiting” overload protection type. This way, the power supply will automatically limit the current to a certain level stated in the specifications:

SPV-150 series specifications

For inductive loads, motors need high current at start-up, therefore a power supply with peak power capability is recommended (or a PSU with constant current limiting overload protection type).

The main issue of dynamic loads is output voltage drop. If the load step is too high in amplitude and too long, it may be able to completely discharge the output capacitors and then create a voltage drop or high ripple at the output. If the frequency of the load changes is high enough, this kind of issue is less likely to happen (please refer to the test reports for more information). One solution could be to put additional capacitors between Power Supply and load.

Some applications may need to draw short peak currents from the power supply. If the PSU overload protection type is hiccup or constant current limiting mode, then it will not be able to provide the current peak needed by the load. Some of our power supplies come with a peak power capability that makes them suitable for these kinds of applications. (e.g. HRP-150N series)

For open-frame power supplies with peak capability, the user should refer to the derating curves, and check the thermal requirements (a fan may be required).

Categories: Industrial, Medical, Operation

Generally, at no load or light load, the power factor is relatively low. In such conditions, although the active power is low, the reactive power and input current is quite high, which results in high measured current using a multimeter. In order to accurately measure the active power, the RMS input current, RMS input voltage, as well as the distrotion and phase shift between V and I curves should be measured (with a powermeter, or an oscilloscope).

If only measuring V and I RMS values, the result is the apparent power, which comprises real and reactive power.
Some models may require to use the Remote Off function to achieve low no load power consumption.

Categories: Industrial, Medical, Operation

Yes, for power supplies certified >2000m please read the “note” in the spec.

In general, for unpotted models, a derating of 5°C/1000m has to be applied and for potted models, a derating of  3.5°C/1000m has to be applied.

For example LRS-75-24:

The datasheet shows:

The Note. 7 shows:

At 5000m the derating curve will need to move 15°C following the arrow (1)

At full load the maximum operating temperature at 5000m will be 35°C shown at (2)

There are some minimum-load requirements on MEAN WELL’s multi-output power supplies. Please read the specification first before connecting to the load. To allow the power supply to work properly, a minimum load for each output is required, or else, the output voltage level will be unstable or outer tolerance range. Please refer to “Current range” in the specification as shown in the table below: Channel 1 requires a 2A minimum-load; channel 2 requires 0.5A; Channel 3 requires 0.1A ; Channel 4 does not need any minimum-load.

Categories: Industrial, Medical, Operation

In general, there are two circumstances that will cause the power supply to shut down. The first one is the activation of the overload 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 these conditions will let the Power Supply enter protection mode and shut down. After these conditions are removed, the Power Supply will be back to normal.

Categories: Industrial, Medical, Operation

Cooling fans have a relatively shorter lifetime (typical MTTF, Mean Time To Failure, of around 5,000-100,000 hours) compared with other components of power supply. As a result, changing operating method of the fans can extend the operation hours. The most common control schemes are shown as below:nnTemperature control: if the internal temperature of a power supply, detected by a temperature sensor, is over the 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 run at half speed. In addition, cooling fans in some power supplies are controlled by a non-linear control method whereby fan speed can be changed with different internal temperatures synchronously.nLoad control: if the loading of a power supply is over the threshold, the fan will start working at full speed, whereas, if the loading is less than the set threshold, the fan will stop working or run at half speed.

At input side, there will be (1/2 ~1 cycle, ex. 1/120 ~ 1/60 seconds for 60 Hz AC source) large pulse current (Ipk 20~100A based on the design of power supply) 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. 

A more critical situation can occur 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 power supply to turn them on/off.

Categories: Industrial, Medical, Operation

Due to different circuit designs, the MEAN WELL power supply’s input consists of three types as below:


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. 
Categories: Industrial, Medical, Operation

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 purposes.

  • Power Good: after the output of a power supply reaches 90% rated voltage, a 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.
Categories: Industrial, Medical, Operation

When current drawn exceeds the rating of the PSU, the protection circuit will be triggered to protect the unit against overload/overcurrent. 

Protections of overload/overcurrent can be divided into several forms:


Output current decreases about 20% of rated current, shown as curve (a) in the figure below. 


Output current remains at a constant level and within the specified range while the output voltage drops to a lower level, shown as curve (b) in the figure below. 


Output power remains constant. As output load increases, output voltage decreases in proportion, shown as curve (c) in the figure below.  


Output voltage and current keep pulsing ON and OFF repeatedly when protection is activated. The unit automatically recovers when faulty condition is removed.


 Output voltage and current are cut off when output load reaches protection range. 

NOTE: Protection mode of some of the products combines with different types of the forms mentioned, such as constant current limiting + shut down.

Recover method:

(1)Auto Recovery: PSU recovers automatically after faulty condition is removed.

(2)Re-power on: PSU restarts by manual AC re-power on after faulty condition is removed.

Note: Please do not operate PSU in overcurrent or short-circuit condition for a long period of time to prevent a shorten lifespan or damaging the PSU.

Categories: Industrial, Medical, Operation

To install a power supply into the system, you would need wires for the connection both to the loads and to the energy source. There are a couple of points that should be taken into consideration when choosing wires, one is the current rating, it may cause high heat on the wires or burnt out in the worst case if the rating is not enough. The other is voltage drop, there would be voltage reduction at load side as current moves through the wires owing to the internal resistance. If too many voltage drop in a line, there could be no sufficient voltage to drive the loads. You can find the right wires for use by referring to the table below on the basis of your system design.

Categories: Industrial, Medical, Operation

If you connect the power supply to motors, light bulbs, or high capacitive loads, you will have a high output surge current when you turn on the power supply and this high surge current will cause failure of startup. We suggest using power supply with constant current limiting protection to deal with these loads.

Categories: Industrial, Medical, Operation

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 affected by this connection.

Categories: Industrial, Medical, Operation

Yes this is normal. Leakage current is the current flowing from the protective earth (PE) conductor, such as metal enclosure, of equipments to frame ground (FG). Due to EMI requirement for the power supply, there are Y capacitors connected in between AC L/N and PE conductor. A low current will flow through the Y-caps to FG. In reality, leakage current should be regulated to comply with safety standards. In regulations of safety for IT products, leakage current should be less than 3.5mA for portable Class I equipment, 0.75mA for hand-held Class I equipment, and 0.25mA for Class IInequipment.

Because of the low current flowing, this is not harmful for the human body. For medical power supplies there are however more strict regulations regarding leakage current.

For more information, please see our Medical Application page

Categories: Industrial, Medical, Operation

Yes in this situation the AUX power is available to be able to use the remote on/off function.

Categories: Industrial, Medical, Operation

During safety verification process, the agency will use a stricter standard ±10% (IEC 62368 uses +10%, -10% for the product with AC input rated) 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.

Tag: IEC62368

The hold-up time is the duration between the instant when the input is shut off, and when the output voltage falls below 90% of the rated output voltage. The hold-up time is highly dependent on the internal capacitances of the PSU and the load: the higher the capacitance, the longer the hold-up time and the higher the load, the shorter the hold-up time. nA common way to increase this parameter is to use buffer modules, such as our DBUF series, or if the hold-up time only needs to be slightly increased, you could use a Power Supply with a higher power rating. (The hold-up time on the specification is based on full load condition)

Categories: Industrial, Medical, Operation

Most MEAN WELL power supplies are certified to be operated till 2000m. For some models the certification is valid for a higher altitude, this will be shown on the first page of the power supply under features (1)(2).
Please note that derating is needed at an altitude above 2000m. See FAQ “Do I need to derate my power supply when I used it over 2000m?

MEAN WELL’s specification shows the absolute values which were verified during design quality verification tests. Those condition are guaranteed by manufacture from quality and warranty perspectives.

When certifying a power supply according to a certain norm, there is normally a requirement described in this standard a certain tolerance which must be considered. (See also FAQ: Why Is The Input Voltage On The Label Different From The Input Voltage In The Spec? For Example, The Specification Shows Is 88~264 VAC While The Label On The Power Supply Says That It Is 100~240VAC?

The specification shows what is possible, the report and label of the power supply shows what is approved by the certifying body according to the standards.

Besides the difference due to tolerance there might also be another reason why the specification and label/test report show a different temperature. For example, if the power supply needs to be derated at a low voltage input such as 100VAC, the label and test report might show the max temperature at full load based on this low input.  

Different standards might have different tolerance requirements and different ranges this could mean that the most conservative value, or multiple values will show up on the label of the power supply.

In general MEAN WELL’s power supplies with a fan will continue to spin in no load condition. For certain power supplies where the fan will turn off in no load condition this will be marked (1) in the feature section of the specification:

Nowadays, customer implement magnetic component in their system to achieve fast installation and maintenance. The magnetic component should keep as far as possible from PSU to avoid interference in the control circuitry of PSU. If limitation of distance is unavoidable, install a well magnetic-conducted metal plate (ex: steel plate, copper plate) between PSU and magnetic component to minimize the interference.

MEAN WELL’s component self-heating can be found on

1. Use the search function on the website to find the right product
2. Fill in the series number in the search field (do not include the last extensions such as -12 in XLG-150-12)
3. Click the search button
4. Click on the PDF icon to open the specification

5. Click on report

6. Click on the model and scroll down:

7. The temperature of the critical component can be found in the chapter Reliability Test under item 1 Temperature Rise Test

For more details about the component type for each position, please use the Contact Us function on this website.

MEAN WELL’s MTBF can be found on

1. Use the search function on the website to find the right product
2. Fill in the series number in the search field (do not include the last 3. extensions such as -12 in XLG-150-12)
3. Click the search button
4. Click on the PDF icon to open the specification

Scroll down in the specification to the bottom of the second page

5. Find the MTBF value in under others:


MEAN WELL’s capacitor lifecycle calculation can be found on

1. Use the search function on the website to find the right product
2. Fill in the series number in the search field (do not include the last extensions such as -12 in XLG-150-12)
3. Click the search button 
4. Click on the PDF icon to open the specification

5. Click on report

6. Click on the model and scroll down:

7. The Capacitor life cycle calculation is shown on the last page of the report in the chapter Reliability test

The Capacitor life cycle calculation is considered as the key indicator for the lifetime of the power supply. Please refer to the test report of the power supply on  for the capacitor life cycle calculation.

As a rule of thumb, every 10dC increase the lifetime will be cut in half and vice versa for every 10dC decrease in temperature.

In the above example, if the power supply is used at 75dC at Ta 40dC, the estimated lifetime would be 2*104095 Hrs ~200K hrs.

This depends on the condition the power supply is used in. Please contact us for specific situations.
In general, the possibility to use the power supply in a higher temperature than specified is very low and all certifications of the power supply will become invalid.

Depending on the cooling mechanism of the power supply there are different considerations and restriction towards the mounting orientation of the power supply and distance towards other components and self-heating components.

In general, please check our power supply user manuals on (Installation Manual-MEAN WELL Switching Power Supply Manufacturer). The actual distance and orientation depend normally on system design. Customers must review and test the power supplies in the real application and environment.

General guidelines for power supplies with different cooling mechanisms:

  • Power supplies with an internal fan or which are cooled with an external fan have less constraints regarding the orientation in which they are mounted. Nevertheless, the fans and ventilation holes must be kept free from any obstructions. Also, a 10-15 cm clearance must be kept from any adjacent heat source
  • A convection cooled power supply with standard a vertical mounting orientation which will be mounted in another orientation have to be derated by 5dC. See FAQ What should be noticed when installing a power supply in vertical and horizontal directions? Additionally ventilation holes must be kept free from any obstructions. Also, a 10-15 cm clearance must be kept from any adjacent heat source
  • Din rail power supplies can only be mounted in the specified orientation. This is with the ventilation holes at the bottom and on top of the power supply. No other mounting directions are recommended. Allow good ventilation clearances, 5mm left and right, 40mm above and 20mm below, around the unit in use to prevent it from overheating. Also, a 10-15 cm clearance must be kept when the adjacent device is a heat source.
  • For conduction cooling power supplies, the temperature on the Tc point is the key indicator if a mounting position can be allowed. The Tc position (1) and max Tc temperature (2) can be found in the product specification. Conduction cooled power supplies are for example IP65~IP68 LED drivers and base plate cooled power supplies such as UHP)  

In MEAN WELL’s specification you can find 2 derating curves, in below example the 300W open frame power supply: EPP-300

  1. The Derating Curve with the Ambient Temperature vs. Load
  2. The Derating Curve with the Input Voltage vs. Load
  1. In this Curve one can find that the maximum load of this power supply is 300W at 50dC when an external air flow of 20.5CFM is applied. For temperatures exceeding 50dC, 60dC for example additional derating need to be applied, in above case at 60dC the maximum load would be 225W. (50dC 300W, 70dC 150W => from 50dC to 60dC:  75W derating)
  1. In case this power supply would be used at 90VAC input, a derating of 80% must be applied. So, in previous example with the 20.5CFM forced air the max load would be 240W. In case of an ambient temperature of 60dC and a 90VAC input the maximum rated power would be 225W * 0.8 = 180W with 20.5CFM forced air.
  1. If the power supply is used in an application without additional forced Air, the power supply will be derated to 200W till a maximum temperature of 50dC
  2. In case it will be powered by a 90VAC input the power supply has to be additionally derated to 80% of the 200W = 160W max

MTBF (Mean Time Between Failure) and Life Cycle are both indicators of reliability. MTBF can be calculated by two different methodologies, which are “part count” and “stress analysis”. The regulations, MIL-HDBK-217F Notice 2 and TELCORDIA SR/TR-332(Bellcore) are commonly used to calculate MTBF. MIL-HDBK-217F is a United States military standard, and TELCORDIA SR/TR-332(Bellcore) is a commercial regulation. MEAN WELL utilize MIL-HDBK-217F(Stress Analysis) as the core of MTBF. The exact meaning of MTBF is, after continuously using the power supply for a certain amount of time, the average time that the probability of proper operation is down to 36.8%(e-1=0.368). Currently MEAN WELL is adopting MIL-HDBK-217F, to predict the expected reliability through Stress Analysis (excluding fans); this MTBF means the probability of the product can continue the normal work after working continuously up to the calculated MTBF time is 36.8% (e-1=0.368). If the power supply is continuously used at double the MTBF time, the probability of proper operation becomes 13.5%(e-2=0.135.

DMTBF (Demonstrated Mean Time Between Failures) is a way of evaluating MTBF in a relatively short period of time based on accelerated deterioration (high stress, high temperature) tests under specific parameters and conditions. Please refer to the following equation for MTBF calculation.
This method compares to the previous methods, this calculation uses real test data to demonstrate the reliability of the power supply.


MTBF: Mean Time Between Failure

  • X2:Can be found in chi-square distribution
  • N:Number of sampling
  • AF:Acceleration factor, which can be derived from acceleration factor equation.
  • Ae=0.6
  • K(Boltzmann Constant)=(eV/k)
  • T1:Rated temperature of specification. Note: Kelvin will be the unit use for calculation
  • T2:The temperature that is used in the meaning of acceleration, and the chosen temperature could not result in physical change in materials. 

Note: Kelvin will be the unit use for calculation.  

Life Cycle (Capacitor Life Cycle) is found by using the temperature rise of electrolytic capacitors under maximum operating temperature to estimate the approximate life of the power supply. For example, RSP-750-12 MTBF=109.1K hours(25°C); electrolytic capacitor C110 Life Cycle=213K hours (Ta=50℃).

MEAN WELL considers the capacitor lifecycle calculation as the most important indicator for the estimated lifetime. The (D)MTBF is the main indicator for the reliability of the power supply. For more information please see:  Investigation of The Lifetime & Reliability of Power Supply -MEAN WELL EUROPE Switching Power Supply

MOOP stands for Means of Operator Protection. This category is related to electronic devices which are handled by trained operators, and do not come into direct contact with the patient. The medical device with 2 x MOOP has an isolation of 3000Vac isolation

MOPP, on the other hand, is the Means of Patient Protection; all electronic devices with direct physical contact with patients must meet stricter standards and require a double isolation between input and output.
For more information, you can find in our medical application section: Medical

Categories: Compliance, Medical

MEAN WELL aims to design the power supply in such way that there is sufficient margin for your system to pass the EMC requirements on system level. However we cannot guarantee 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.

Categories: Compliance, Industrial, Medical

MEAN WELL’s safety reports, IEC reports and CB reports are not available online. In case you need these reports to validate your design with your certifying body, please contact your local MEAN WELL sales channel for support. If you are unable to get the support, please contact us via this website.

Tag: CB reports

MEAN WELL’s User Manual can be found on
1. Go to products
2. Click on Installation Manual

3. Scroll down to find the user manuals for the different product families.

MEAN WELL’s Safety certifications can be found on

  1. Use the search function on the website
  2. Fill in the series number in the search field (do not include the last extentions suchs as -12 in XLG-150-12
  3. Click the search button

4. Click on the PDF Link

5. Click on the top on the certificate
6. All available certificates are shown and will show up once clicked upon

MEAN WELL’s CE declarations can be found on

  1. Use the search function on the website
  2. Fill in the series number in the search field ( do not include the last extentions suchs as -12
  3. Click the search button

4. Click on the PDF Link

5. Click on the top on certificate
6. Click on CE declaration

Select (1) Products followed by (2) downloads

MEAN WELL’s EMI test guide can be found on

Select (1) Products followed by (2) Downloads

Or you can use this link to directly download the EMI testing guide:

Tags: EMC, EMI

MEAN WELL’s RoHS and Reach statements can be found on

Select (1) Products followed by (2) Downloads:



After this scroll down to find the RoHS declaration and Declaration of SVHC/ REACH conformity:


Or you can use these below links to download the declarations:

REACH SVHC Delaration.pdf


MEAN WELL’s Declaration of Conflict Free Minerals can be found on

Select (1) Products followed by (2) Downloads

After this scroll down to find the Declaration of Minerals Conflict Free

Or you can use this Link to directly download the EMI testing guide:

Download the EMI testing guide