Why is the input voltage indicated on the specification ranging from 90 to 305 V A C and the 100-277 V A C shown on the LED power supply product label?

In the safety regulation approval process, the review agency will use stricter test methods to test the product. When testing the input voltage, they set a tolerance ± 10% of the input voltage on the product label. So it is also normal to work at the voltage described in the specification. As for the voltage marked on the label, one purpose is to meet the requirements of the safety regulation, on the other hand is to enable the customer to properly access the appropriate working voltage.

What is the difference between isolated and non-isolated drives?

Non-isolation refers to the direct electrical connection between the output terminals and the input terminals.The lack of transformer isolation in non-isolated circuit means that the LED is more vulnerable to surges from AC power sources due to load switching transients or primary side interference. Isolated drivers: 1. Flyback converter topology 2. more expensive  3. High efficiency 88%.  Non-isolated drives: 1. Buck or step-down-boost topology 2. More efficient 3. Insulation leads to less heat dissipation.

How to distinguish constant current power supply from constant voltage power supply ?

According to the circuit design, LED power supply is generally divided into constant current power, constant voltage power, constant power power, constant current IC, etc. Today, what we are talking about in current LED lamps, mostly is constant current power supply. The output current of the constant current driver power supply is constant (± 5% accuracy), and the output DC voltage is changed within a range, as the load resistance value varies in a certain range. The output voltage is low when the load resistance value is small, the output voltage is high when the load resistance value bigger,for example: AC100-240V DC30-40V 800MA (± 5%).

Constant voltage driver power supply means that when the parameters in the voltage stabilization circuit are determined, the output voltage is fixed, and the output current changes with the increase and decrease of the load, such as: AC100-277V DC24V 0-1250mA.

How to distinguish class I power supply from class II power supply?

According to European standard, class I power supply has grounding protection, and class II power supply has no grounding protection. For some partial of our class II power supplies, customers are actually used in lamps which is class I , that is, the power supply is not grounded, but the lamp shell is grounded, and special attention should be paid to whether the conduction radiation of the whole lamp can meet the certification requirements.

According to the US standard, the class 2 power supply must be an isolated power supply, with an output voltage below 60Vdc, less than 100W, and 150W in an abnormal state.The American Class 2 is equivalent to the European American SELV. In the European standard, the SELV standard is satisfied if the output voltage is <120Vdc.

Please note that the European standards are I and II, and the American standards are 1 and 2.

What is the European standard power supply and the American standard power supply?

Most high voltage countries (input voltage is generally 220-240V), including the EU, New Zealand, Australia, China, the Middle East, most Asian countries (except Japan and Taiwan), their certification system is interlinked(CE,ENEC,CB,RCM,CCC,etc.) Most of the power suppliers we sell to these countries need to meet the above certification, so we generally call this part of the power supply European standard power supply internally.For countries represented by the United States that require low voltage or full voltage input: AC100V (Japan), AC110V (American civil voltage, Taiwan, Colombia), AC120V (Costa Rica, Venezuela), AC125V (Mexico), AC277V (American industrial voltage), the power input supply must be AC100-277V (rated range), so our internal communication is generally known as the American power supply.

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