If you use the peak power supply products encountered problems, please give priority to search the following common problems can solve your problem. If the answers to the above questions are not available for you, please contact the nearest local distributor and our dealers will reply to you as soon as possible!

DingFeng-Power is a professional manufacturer for standard power supply, power supply products market demand to develop many kinds of. Select the appropriate power supply products in which the relevant specifications, electrical functions or product reliability is what you pay attention to. Therefore, the following common problems, please refer to!

Functional aspects


Select POWER SUPPLY notes?

1. In order to make POWER SUPPLY the life of more than 30% growth, suggested the use of the outputpower models. For example, if the power system requires a 100W, is recommended to choose more than 130W rated output power of the aircraft, and so on can effectively improve the life of SUPPLY POWER.
2. In addition to consider the working temperature of the POWER SUPPLY, and whether there is an additional auxiliary cooling equipment, in the high temperature of the ring POWER SUPPLY need to reduce the output. Derating curve of ring temperature to output power.
3. According to the needs of the application to select the functions: 4 select the required compliance with the safety and electromagnetic compatibility (EMC) certification.
4. Protection function: over voltage protection (OVP), over temperature protection (OTP), over load protection (OLP), etc..
5. Application function: signal function (POWER GOOD, POWER FAIL), remote control, telemetry, parallel functions,

What is power good and power fail signals and how can use it

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.


What is the fan control mechanism for SPS with cooling fan?


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:

  1. 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.
  2. 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

In DingFeng Power's catalog, we see AC and DC at input, what


Due to different circuit designs, DingFeng Power power supply's input consists of three types as below:
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.    

What is the difference between -V and COM which are marked o

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)

What is PFC?

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.

What is "Inrush Current"? What will we notice?

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.

Why the fan is not running after turning on certain models?

Some models control the fan based on internal temperature to extend its life time. For example, the Fan ON temperature for the LRS-350 series is ≧ 50℃ (RTH3). If the internal temperature does not reach the preset value, the fan will remain still until receiving the start up signal.

Measurement of two sets of output power, +5V is correct, +12

There are some minimum-load requirements on DingFeng Power'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 ±6% 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.

May I ask if the DingFeng Power can be used in 45~440Hz, if

DingFeng are generally available in this frequency range. But the use frequency is too low, will cause efficiency decline, such as: SP-200-24 operation on the input voltage 230VAC and rated load, when the input current frequency is 60Hz, the efficiency is 84%, but if the input current frequency is 50Hz, its efficiency is 83.8%; while too high will make the PFC function with the models. The decrease of PF value, also will cause the increase of leakage current, such as: SP-200-24 operation on the input voltage 230VAC and rated load, when the frequency of the 60Hz input current, power factor is 0.93 and the leakage current of 0.7mA; and when the input frequency AC power is 440Hz, the power factor is reduced to 0.75, while the leakage current increased to 4.3mA.

I have an TN-1500 inverter. Why the LED indication of AC IN

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 ?5% 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.

What is minimum load requirement and how can I read it from

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.

What is MTBF? Is it distinct from Life Cycle?

MTBF 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 uses MIL-HDBK-217F(Stress Analysis) as the core of MTBF. The exact meaning of MTBF (Mean Time Between Failure) 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, forecasting the expected reliability through Stress Analysis (excluding fans); this MTBF means the probability 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 contin

Why did the power supply shuts down during operation and aft

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.