Mean Well Switch-mode Power Supplies Manual

Switching power supplies are widely used all over the world. Many types of products are available for both alternating and direct currents. Before using the power supply, make sure that the output voltage is suitable for the intended load. Verify the correct input switching method and any other conditions that might affect the power supply's operation.

If an input voltage is applied which is different from the power supply's rating, the unit may be damaged.

Remember that if the input voltage wave is distorted, the power supply will not operate normally, even when the voltage is within the allowable range.

Input Voltage Range (Safety Approved Models) For all Safety Approved Models refer to the label on the power supply case for the input voltage range.

Fig. 1 - World Voltage guide
Fig. 1

1.2 Input Current

Standard power supplies directly rectify the input alternating current. Most standard units are capacitor-input-type, rectifying systems in which rectified current flows through the filtering capacitor. Therefore, the input current is determined by the output power, input voltage, power factor, and efficiency.

Figure 2 - Input block diagram
Fig. 2

The power factor of the typical switching power supply is between 0.4 and 0.6.

1.3 Inrush Current

When power is applied to the power supply, the peak current flows inside to charge the input filtering capacitor. This current is called the "inrush current". The value of the inrush current varies according to the power-on timing and the presence or absence of the inrush current protection circuit. The inrush current is several to tens of times larger than the normal input current. The more switching power supplies used in the same system, the larger the inrush current. Carefully select the fuses, switches, and other parts when adding them to the input line.

Fig. 3 - Example wave forms
Fig. 3

1.4 Input Fuse

If the switching power supply's built-in fuse is blown, something may be wrong in the internal circuits. In this case, the switching power supply will not recover even if the fuse is replaced, contact the manufacturer or reseller.

IMPORTANT NOTE

All information is based on the Mean Well Switching Power Supply User Manual - Version 1 and is provided in good faith, but without any warranty or guarantee as to fitness to purpose. It is solely left to the discretion of the user as to the suitability of the information for their application.

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