How To Choose an LED Power Supply
May 22 2019
Whether you are building your own LED fixture, fixing and retrofitting existing fixtures, or purchasing new LED lights, you will need to find the correct power source for your LEDs. You will either need a constant current LED driver or a constant voltage power supply (or a combination of both) in order to make your LEDs work properly. There are many different factors to consider when choosing a power supply for LED lighting. This post will go through those many factors and help you select the right power supply for your LEDs!
First of all... Make sure you can control the current of the LED
Most leds require current limiting devices (either drivers or resistors) to prevent LED overdrive. The constant current driver or current limiting resistor is used to regulate the current of the LED to keep it running safely and maximize its service life. LED electrical characteristics change with heating; Without current regulation, leds can absorb too much current over time. This excessive current will cause LED brightness to fluctuate, leading to high internal heat and ultimately LED lamp failure. If you are building your own LED lamps or using any of our component star leds, you will need a constant current device in the system. Most finished LED products or LED strips (which you can buy directly from the store) already have drivers or resistors built in to regulate the current. If you're not sure you need a constant current source, take a look at the useful posts to find out. If you don't have a limited-flow device, finding the driver is your first step; But if your LED is already under current control, you can follow this article to find a constant-voltage power supply.
Constant voltage power supply
A constant voltage supply can be used to supply LED lights that already have resistors or constant current drivers in the system. These types of products usually require a constant dc voltage. If you use battery power or happen to have enough dc voltage for your lamp, consider yourself lucky. In nine out of ten cases this is not the case and you will need a power supply to convert the power supply to the lamp's safe dc voltage. For example, the LED flexible strip has an on-board current-limiting resistor (such as the LED- flexible strip on the circuit board, the resistor you can see built into the flexible strip base). If you want to install it in your car, you don't need any power. The car battery sends out 12VDC to give or take away. The battery's 12V power supply is perfect for your lamp. But in order to integrate these strips into the home, you need an ac-dc converter that takes the standard household voltage of 120VAC and converts it to 12VDC.
How to choose the right power supply?
Therefore, you need some type of constant voltage power supply that can reduce your ac home voltage to a safe dc voltage. There are many factors that can help you find the right power source for your needs. First, we should lock up the power needed for the power supply.
To get started, know how many watts your lights will consume. If you want to run more than one lamp from one source, you must add up the wattage to find the total wattage used. Make sure you have a large enough power supply to have a 20% buffer on the total wattage you calculate on the LED. This can be easily done by multiplying the total wattage by 1.2 and finding the rated power supply.
For example, we have four LED strips running, each running about 12 watts. Simply multiplying by these will indicate that our system power should be around 48 watts. Now we can add the 20% recommended mat, 48 x 1.2 = 57.6 watts. A 60-watt (or higher) power supply is enough for the project.
It is important to verify that the output voltage is compatible with the LED voltage when building LED lamps or replacing defective power supply. LED products with built-in current regulators are usually well suited for specifying the input voltage to be used. For example, a 12V power supply will be used with our LED flexible strips as this is what they need.
Another common application is the use of high-power leds with constant current drivers, which require a DC voltage input. Suppose we have 6 Cree leds using the Mean Well ldd-h driver. The voltage of each LED is about 3.1 volts. The total voltage of the four circuits is 18.6VDC. Typically, a low-voltage driver like Mean Well ldd-h works better if it has a small buffer over the required voltage. For this setup, I'll use a power supply that outputs at least 24VDC. Note that you should always ensure that the rating of the low voltage driver used (in this case, the average ldd-h) is the voltage you want to input. The average ldd-h can adopt 9-56vdc, so we are all in this situation. Learn more about calculating voltages in different circuits here.
Also, be sure to select a power supply that can handle your input power. The line voltage will vary depending on where you are in the world. Make sure you know whether there is a low voltage ac power supply (90-120vac) or a high voltage ac power supply (200-240vac). Many power supplies, such as Mean Well products, will be rated on a full scale, but it is always helpful to know your AC inputs and make sure the power supply you use is appropriate.
Adjustable LED power supply
If your LED is dimmable and you want to adjust its brightness, be sure to select a dimming power supply. The power supply specification shall state whether the power supply is dimmable and the type of dimming control it USES. I will briefly introduce two types of controls:
PWM dimming: also known as pulse width modulation dimming, can be used for all power supplies. Even if our website does not say "dimmable" power supply in the specification, it can be dimmed by wall mounted or remote PWM dimmer. This is because the PWM dimmer is in series with the strip lamp, dimming at the 12VDC side of the circuit. The PWM dimmer actually USES high-frequency pulses of light to change the perception of light to the naked eye. The higher the frequency, the brighter they are.
TRIAC dimming: this dimming allows LED dimming with a standard dimmer. You must check the specifications to ensure that the power supply meets the ac (TRIAC) dimming requirements. The product we currently provide for such dimming control is the amount of energy Dimmable Power Supplies. These power supply SCR dimming LED strips change the power on the ac side of the circuit through the TRIAC dimmer. The power change generated by the dimmer on the AC input side will change the voltage on the DC output and control the brightness of the LED. TRIAC dimmers can be found in regular hardware stores. The most popular/well-known brands are Lutron and Leviton.
Temperature and weather
An important factor to consider when choosing a power source is the area and environment it will be used in. If the power supply is used in the range of its temperature parameters, the power supply is the most efficient. The power supply specification shall include a safe operating temperature range. It is best to operate in this area and make sure that the power supply is not pasted where it may generate heat and exceed the maximum operating temperature. It is usually a bad idea to fix the power supply in a small enclosure without a ventilation system. This will allow even the smallest amount of heat generated by the source to accumulate over time and eventually cook up the power supply. Therefore, make sure that the area is not too hot or too cold and that the heat does not reach destructive levels.
Each LED power supply also has a protection rating (IP). The IP level consists of a two-digit code that indicates the amount of solid and liquid pressure that the power supply can resist. The first number refers to the solid size that the device can withstand, while the second number refers to the amount of liquid that the device can withstand. As each number increases, so does the level of protection. As the first number increases, the product is protected by smaller and smaller objects (all the way down to dust particles), making it less susceptible to any intrusion and damage. As the second number increases, the product goes from being protected only in light rain to fully immersive. IP- rating, explained
The efficiency of
The efficiency of the power supply represents the amount of power actually used to light the LED. The higher the percentage of power efficiency - the more power you'll end up saving. For LED applications, the best choice is 80% efficiency or higher power. Check the Mean Well and Phihong power sources for the most efficient selection, as their efficiency levels can be up to 90%.
When selecting a power source for an LED project, it is important to know where it needs to be installed or installed. If you want to put it into the product you're working on, it must be small enough to fit the space provided. If it's outside the application, it should have a way to get around. Power supply in various sizes and shapes to meet your needs. LED- power supply, dimensions
Level II or level 2?
It's easy to confuse the two ratings, so let's make sure we've got it under control now that we're starting to understand LED power. Class 2 power supply conforms to the limited power level specified by the national electrical code (NEC) and meets the requirements of UL 1310 standard. Class 2 power supply is limited to 60VDC and 100w. Due to the limited power, class 2 power supply cannot supply power to other LED beyond the rated value. At this point, you must determine whether to run longer from one power source, or adhere to the safety of using fire and shock resistant type 2 power sources.
Class II actually only means that the input and output lines are double insulated. Class II drivers are popular because they do not require grounding.
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