Dimming with LED
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Dimming with LED
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Dimming with LED

Why do some LEDs flicker when dimmed or turned off?

This is usually due to incompatibility between the driver and the control system. When purchasing an LED product, it is important to use the correct driver type as specified by the manufacturer. It is also important to check that the LED is dimmable. Some retrofits are not.

What lighting protocol is appropriate for an application?

For applications where single colors and white LEDs are used, analogue or PWM dimming protocols can be used to switch or dim LEDs. For intelligent controls like creating dynamic effects, tuning of white light etc, DMX or Ethernet protocols can be used. Digital dimming works better with large numbers of luminaires.

What is the difference between analogue and digital dimming?

Analogue dimming is usually referred to as 1 - 10v dimming. In this case, a dc voltage is sent to the driver, which dims the LEDs in response to the voltage. With digital dimming, the driver receives a digital signal which tells it how to respond. The advantage of digital dimming is that fixtures are addressable. You can also have many more different levels of light output when using digital dimming.

What are the relative advantages of PWM dimming?

Following are the advantages of PWM dimming:Smooth dimming capabilityMore precise output levelsBetter consistency in color over various levels

How are LEDs dimmed?

LEDs are dimmed either by Pulse Width Modulation PWM, or by Constant Current Reduction CCR. PWM dimming involves switching current at a high frequency from zero to the rated output current. CCR dimming: The lighting level required is proportional to the current flowing through the LED. Current flows through the LED continuously and is reduced or increased based on whether the LED is to be dimmed further or made brighter.

What precautions are to be taken when mounting LED drivers?

LED drivers need to be mounted in a ventilated space. Access to the driver needs to be provided for general maintenance purposes. The IP (ingress protection) rating of the driver needs to be considered before finalizing the mounting location of the driver (only those drivers designed for outdoor environments can be located outdoors). The distance between the driver and the light source needs to be taken into consideration in order to prevent voltage drop, which results in reduced output of the LEDs.

What are the advantages of 24V LEDs over12V LEDs?

LEDs driven by 24V drivers have longer permissible distances between light source and driver compared to 12V DC LEDs. 12V LEDs are usually suitable for applications where low light outputs are required. 24V LEDs offer products with higher outputs than 12V products.

What is the maximum permissible distance between an LED product and a remote driver?

The maximum permissible distance is dependent on the LED load, the conductor size, and the driver used. There is little practical limit on the distance between the driver and LED if you are using a constant current driver because it increases the output voltage to overcome any volt drop caused by the cable length. The distance between the LED and the driver is more important for constant voltage drivers where there is a voltage drop due to the load and length of cable.

How do I know what type of driver is required by LED product?

The LED rating of a product is usually noted in milliamps, mA or volts, V. Products rated in mA can be used with a constant current driver, while those rated in volts can be run with a constant voltage driver. LEDs designed for constant current drivers cannot run with constant voltage drivers without damaging them.

Typically in what sort of applications are constant voltage drivers are used for?

Constant voltage drivers are used in applications where the load is not known and the LED loads are connected in parallel, for example in coves and signage applications. These drivers are sometimes similar to the low voltage electronic and magnetic transformers used in halogen light fixtures (MR16 lamps). The type of LED driver suitable to run a LED product is stated by the LED manufacturer in the product specification.

Typically, what sort of applications are constant current drivers used for?

Constant current drivers are typically used in downlights where one, or a series, of luminaires is used per driver. These are connected in series.

What are there different types of LED power supplies / drivers?

LEDs are driven by constant current (350mA, 700mA or 1A) drivers or constant voltage (10V, 12V or 24V) drivers.Constant current drivers fix the current of the system and vary the voltage depending on the load of the LED.Constant voltage drivers require a fixed voltage, and the LED loads are added in parallel across the output of the driver until maximum output currents are reached.

Why do LEDs require power supply / drivers?

LEDs are low voltage devices. Therefore, they require a device / Power supply unit / driver, or integrated electronics that convert line voltage to low voltage in order to run the LEDs. Sometimes The driver has electronics that can interpret control signals to dim LEDs.