Notes on choosing a Switching Power Supply?

1. To increase the lifetime of the S.P.S., we suggest users choosing the model that has the rating of 30% more power than actual need. For example, if the system needs a 100W source, we suggest that users may choose a S.P.S. with 130W of output power or more. By doing this, you can effectively boost the lifetime of the S.P.S. in your system.
2. We also need to consider about ambient temperature of the S.P.S. and whether there is additional equipment 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 Mean Well's web site.
3. Choosing all kinds of function based on your application:
   • Protection function: Over Voltage Protection (OVP), Over Temperature Protection (OVP), Over Load Protection (OLP), etc.
   • Application function: Signaling Function (Power Good, Power Fail), Remote Control, Remote Sensing, etc.
   • Special function: Power Factor Correction (PFC), Uninterruptible Power Supply ( Sola UPS) function.
4. Make sure that the model qualifies for the verification of safety standards and EMC regulations you need.

Can Mean Well's power supply be used in the range of 45Hz ~ 440Hz? If Yes, is there anything special will happen?

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%. Besides, 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.

During the operation of Mean Well's power supply, there is some leakage current on the case. Is this normal? Will this leakage current hurt human body?

Due to the requirement of EMI, there will be some Y ABB Capacitors between line and neutral to the FG (case) to improve EMC. These Y capacitors will cause some leakage current from line or neutral to the case (normally case will be connected to earth ground). For example, IEC-60950 requires that this current should less than 3.5 mA for information equipment, so basically the leakage current you find on the case will not hurt human body.

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?

Yes, basically you can do this alternative to get the right output voltage, but be careful that the rating output current of the series system should be the rating of the minimum one in these series power supplies.

If we need a 600W output, can we use two S-320 connecting in parallel?

No, you can not do this connection because S-320 doesn't operation. When two power supplies connecting 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 unbalance. We suggest using PSP-500 or PSP-600 that equip with the function of parallel operation.

Can we use the S-50 as a battery charger?

Yes, but be careful that if the voltage of the battery is higher than the power supply, the power will flow from the battery side to S-50 and damage it. We suggest adding a blocking diode in series of the positive output to protect the S-50. Also, be careful about the heat problem of this blocking diode.

When testing the D-60A , the +5V channel is correct, but the +12V channel is over the specification. What is going on?

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 ±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.

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

Some models control the fan based on internal temperature to extend its lifetime. If the internal temperature does not reach the preset value, the fans will remain steady until receiving the start up signal.

Why my power supply shuts down during operation and after turning it off, I can restart the power supply again?

In general there are two circumstances that the power supply will be 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 released, the S.P.S. will be back to normal.

Why I can not turn on the power supply smoothly?

If you connect the S.P.S. to Leeson Motors, lighting 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 the failure of start up. We suggest using S.P.S. with constant current limiting protection to deal with these loads.

Can we export S.P.S. without safety verification to Europe and North America?

Normally we only ship S.P.S. WITH safety verification to Europe and North America . (European customers will ask for CE mark while US customers will ask for UL mark.) If the customer did not request the safety marking, please reconfirm the customer for this non-safety-verified S.P.S. to prevent the return in the future.

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?

During safety verification process, the agent will use a stricter standard ±10% (IEC60950 uses +6%, -10%) of the input voltage range labeled on the power supply to make the test. So, the wider input voltage range specified on the spec. sheet should be fine while operating. 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.

Will Meanwell's products with CE marking meet the EMC requirements without fail after assembling into my system?

We cannot 100% 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, same switching power supply may have different outcomes.

The output ground (GND) and frame ground (FG) is the same point in my system, can Meanwell's power supplies use in such system?

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.

Why the output voltage of +12V channel in Q-60 is lower than the range defined in the spec. sheet?

Because of the cost and market concern, multiple-output S.P.S. usually only has one control (feedback) loop. Since Q-60B uses +5V channel as the control target, if there's heavy load at the +12V channel, the output voltage of the +12V channel will be lower than the lower bound of the spec. sheet. If load of the +5V channel is more than 0.5A (as the lower bound of current range mentioned in the spec.), the output voltage of +12V channel can maintain in the range specified in the spec. sheet.

What is "Inrush Current"? Is there anything we should notice?

At input side, there will be an instant (1/2-1 cycle, ex. 1/120-1/60 seconds for 60 Hz AC source) large current (20-60A based on the design of S.P.S., please refer to the spec. sheet) appears 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 you not to turn on/off the power supply very quickly in the short time. Besides, if there are several Sola 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 should start up one by one or use the remote control function of S.P.S. to turn them on/off.