MEAN WELL’s power supplies have been used in a wide variety of electronic equipments, including factory control, IT, communication, appliances, medical, lighting, billboards, security, vehicle, etc…. , which is capable of meeting your needs.
How to choose a suitable power supply for a charging application?
MEAN WELL has launched ENC, HEP-600C, GC, PA, PB, RPB and RCB series for battery charge applications (30~360W). However, if these models still cannot fulfill customer’s requirements, there is an alternative for the purpose. Power supplies with constant current limiting as overload protection are suggested. Charge current varies in battery percentage (full or flat), there is high possibility to trigger overload protection when battery is low, those with overload protection as hiccup or shutdown will stop charging the battery in low battery condition. Yet, using a power supply as charging purpose is considered as over load usage, modification is required. Please contact MEAN WELL for the request.
what are the applications for PSUs connected in series?
there are two types of the applications, one is to create positive and negative voltages, one is to build higher output voltage. Connection methods are shown as below：
(1)Positive and negative voltage
(2) Increase the output voltage (current does not change). If there is no reverse blocking diode in the power supply, we should add an external blocking diode to prevent the damage of power supply while starting up. The voltage rating of the external diode should be greater than V1+V2. Transit current rating of diodes shall be greater than rate output current of S.P.S.
Requirements on parallel operation？
When power supplies are connected in parallel, it is able to increase the output current or use them as the redundant (back-up) function. Be sure that the difference in
output voltage and wiring impedance should be small when operating in parallel.
1. Connect P(LP/CS) terminals together such as the PSP models (Please refer to the parallel function of specification). Input and output should be connected in parallel before connecting to the AC source and loads. Shown
as in picture below (some S.P.S. require a minimum load after paralleling).
2. Output voltage difference between S.P.S. units should be as small as possible, normally < 0.2V.
3. The power supplies should be paralleled with short and large diameter wiring together first, and then connected to the load.
4. After paralleling, the maximum usage of total power should be around 90% of the rated total power.
5. When power supplies are paralleled, if the load is lower than 10% of rated load of individual S.P.S. The LED indicator or signals (Power Good、Pok、Alarm Signal) may malfunction.
6. To ensure that the load current is effectively shared in parallel operation, in general, it is recommended not to use more than 4-6 power supplies at one time.
7. In some models, the +S, -S terminals should be used to reduce unstable pulsation of output voltage.
Why I can not turn on the power supply smoothly when the loads are motors, light bulbs or capacitive loads?
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.
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?
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.
During the operation of your 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 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.
For certain need, is it possible to reduce the noise of fan?
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.
What should be noticed when installing a power supply in vertical and horizontal directions?
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.
How to select a suitable proper circuit breaker or fuse for MEAN WELL SPS?
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).
Can MEAN WELL charger use on Lithium battery or other type of battery?
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.
Points on connecting wires used in power supplies?
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 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 much voltage drop in 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.
How to select adaptors with the correct AC plug for use in different countries?
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.
A few things you should know before using the Remote Sensing function
First, use twisted wires, connect +S to the positive end of the output, then -S to the negative end of the output, as shown in the illustration. Also, keep the wires off the AC and output cables to prevent noise interference.
Add capacitors at output end where the Remote Sensing wires are connected to if dynamic load (frequency above 1K Hz) is used. The purpose is to reduce noise as Remote Sensing is a sensitive function. A suitable capacitor requires two factors:
a. Rated Ripple Current is 0.2 times greater than the output current
b. Rated Voltage is higher than the output voltage