MEAN WELL recommendations for connecting medium and high power power supplies


For power supply systems, it is important both to comply with the specified power supply parameters (voltage, current) and to ensure safety during operation. The circumstances that directly affect safety are not only the conditions for placing the power supply, but also the choice of connecting wires, and their connection to the power source and load. The correct choice of all components allows you to reduce the loss of electrical power during the transmission of energy from the source to the load, as well as eliminate the risk factors of failure of the power supply system and equipment, including the risk of fire.

The presence of losses in electrical engineering is based on the fact that almost every conductive material, for example, copper, has its own (specific) resistance. So, the resistance of the connecting wires is determined by the formula:

Formula soprotivleniya soedinitel'nyx provodovThe formula of resistance of connecting wiresAs can be seen from the formula, the losses are directly affected by the length and cross–sectional area of the wire, and the longer the length and the smaller the cross-section, the higher the resistance to electric current in the wire will be and, as a result, there will be more losses.

Ultimately, these losses are expressed in heating of the connecting wires, and the higher the current flowing through them, the higher the heating will be, which can lead to melting of the insulation and the risk of fire. Therefore, when choosing connecting wires, it is important to select their cross-section based on the maximum allowable current flowing through them:

Rekomenduemyj kalibr AWG i sechenie provoda v zavisimosti ot maksimal'nogo tokaRecommended AWG gauge and wire cross section depending on the maximum currentPowerful power supplies have wide terminals that allow you to pass all the output power (current) in full.

Such terminals are available in the series of case-type power supplies RSP-1000, RSP-2000 and others. For example, the RSP-1500 power supply has two wide contacts of positive and negative polarity:

Vyxodnye kontakty istochnika pitaniya RSP-1500Output contacts of the RSP-1500 power supplyHowever, not in all cases it is possible to use terminals or contacts of a suitable size to pass a large current.

For example, for high-power DIN rail power supplies of the NDR-480, SDR-480, SDR-960 series, it is not possible to place terminals of this size in the power supply housing. In such cases, the terminal block has several terminals of the same polarity – 2-3 contacts for each output "+" and "-":

Vyvody na klemmnoj kolodke LRS-600Terminals on the terminal block LRS-600All these contacts are fully connected to each other, however, the cross section of each terminal is small to pass the maximum current, therefore, in this case, all the terminals of each polarity must be used to connect the output cable, and the cable suitable for the power supply must be parallelized to the appropriate number of terminals.

Otherwise, if there is a connection through only one pair of terminals, a local overheating will occur on them with possible melting of the insulating material (plastic) of the terminal block, which can cause a short circuit or lead to a fire.

Thus, we can distinguish the following recommendations for connecting medium and high-power power supplies from MEAN WELL:

  1. The correct choice of the type and cross-section of connecting wires, depending on the maximum current of the power source.
  2. All contacts of each polarity on the terminal block of the power supply unit must be involved, due to parallelization of the cores or wires in the cable.
  3. Compliance with operating temperature conditions to prevent overheating of the power supply.
  4. The output current and power must not exceed the permissible values. It is advisable to use additional protective measures to prevent this.

For more details, the technical characteristics and features of the MEAN WELL power supplies are presented in the Specifications on the product page. For advice or clarification of information on MEAN WELL power sources, you can contact by e-mail .