From time to time there are problems with LED lighting fixtures. The novelty of LED technology can complicate the diagnosis and correction of these difficulties. Below is a list of malfunctions that may occur, with a description of the process of determining the cause of their occurrence and possible means of resolving it. In particular, you will learn how to eliminate the flickering of LED lamps.
Problem: LED flickering. Possible Cause # 1: Incorrect Voltage
LED lights require compliance with certain input parameters. Inappropriate driver voltage can cause the LED lamps to flash or flicker.
To fix the malfunction, it is necessary to check the input voltage of the driver (for example, 120 V) and the lamp (for example, 277 V). The problem may be their inconsistency. In this case, you should replace the driver or the lamp itself so that the voltage values coincide, or, if this is not possible, install a transformer that could provide the required parameters of the LED lamp.
Possible Cause # 2: Incompatible Dimmer
Flickering of LED lamps occurs if the luminaire is not designed for a specific load of the dimmer or if the driver is incompatible with its control circuit.
To diagnose this problem, you must turn off the brightness control circuit . If the LED functions normally, then the dimmer or its load are incompatible with it. Contact the lamp manufacturer for an explanation of whether the driver is dimmable and, if so, which devices are compatible with it.
Possible reason # 3: rated power of presence detector or dimmer
For the proper functioning of these controls, a minimum rated power is sometimes required. For example, the presence sensor control unit may require a load of at least 20 watts, and the LED consumes only 10 watts.
To eliminate the flickering of LED lamps, additional devices must be added to the circuit that increase the load power to the required for normal operation of the device, or replace the presence sensor or dimmer control unit with another one with more moderate requirements for power consumption.
Possible reason No. 4: dimmer overload
A common problem with the LED lighting control system is the unintentional overload of the LED driver. It is designed for maximum load (measured in volts, amperes and watts), which should not be exceeded.
The number of lamps that can be installed on a single-phase dimmer, to calculate, it would seem, is quite simple. For example, you need to find out how many 15-watt LED lights can be installed on a 600-watt dimmer. The quotient of dividing 600 by 15 determines that 40 lamps can be controlled. Unfortunately, this result is sometimes incorrect. In fact, a device of this power allows you to use only 6 LED lamps.
Although the total LED power is only 15 watts, the inrush current and repeated half-period inrush currents load the dimmer much more. Thus, a 15-watt LED lamp for a dimmer will be equivalent to a 100-watt incandescent lamp. In this case, if more than 6 light sources are used, the dimmer will be overloaded.
The average values of starting or half-period current surges are equivalent to the current consumed by a 100 W incandescent lamp, even with a load of less than 20 W!
The flickering of LED lamps can be eliminated by following these steps:
- refer to the technical characteristics of the fixtures to determine the equivalent load;
- remove the dimmer from the lamp power line and find out if this solves the problem;
- replace the dimmer with a device with a higher maximum load;
- split the circuit into several loads.
Possible Cause # 5: Light Dimmer
Some dimmers with incorrect load function incorrectly. For their normal operation, a certain minimum number of fixtures may be required, based on the 25-40 W required for a conventional dimmer. One incandescent lamp easily meets the minimum load requirements. But LED fixtures may need 4 times more.
To eliminate the flickering of LED lamps caused by low load dimmer, you should:
- refer to its technical characteristics to determine the minimum load;
- remove the dimmer from the lighting circuit to ensure a solution to the problem;
- replace the dimmer with a device with a lower minimum load.
Problem: Flickering off LED lamps. Possible reason number 1: interference from nearby wiring
Flickering of LED lamps in the off state occurs if a wiring is laid in parallel along which current flows. In a disconnected conductor, voltage arises, which is the cause of the flashing of the lamp.
You can solve the problem by the following methods:
- parallel to the luminaire, connect a shunt capacitor with a capacity of 0.01–1 μF, a voltage of at least 400 V or a resistor with a power of 0.5–2 W and a resistance of 100 kΩ – 1.5 MΩ, through which the backlight supply current will flow;
- parallel LED connect incandescent lamp.
Possible Cause # 2: Backlight Current
When a backlit switch and an LED lamp are used, flickering occurs even when it is turned off. The backlight consumes current, which charges the capacitor of the electronic circuit of the lamp to a level sufficient for the flash.
How to remove the flickering of LED lamps in this case? You must use one of the following methods:
- parallel to the luminaire, connect a shunt capacitor with a capacity of 0.01–1 μF, a voltage of at least 400 V or a resistor with a power of 0.5–2 W and a resistance of 100 kΩ – 1.5 MΩ, through which the backlight supply current will flow;
- parallel LED connect incandescent lamp;
- replace the illuminated switch with the illuminated one-way switch, connecting it so that both contacts of the lamp are closed to the neutral wire when off;
- replace the backlit switch with a regular one;
- backlight power through a separate neutral wire;
- remove the backlight of the switch.
Problem: LED lamp does not light. Possible Cause # 1: Incorrect Wiring
In that case, there may be a bad connection between the LED and the driver, the network and the lamp. Check all electrical connections between the LED and the driver and between the line and the driver and make sure that the voltage is correct. Make sure that all circuit breakers are turned on and all connections are made correctly.
It is necessary to check all wires connected to the luminaire, including phase, zero, ground, dimming circuits and emergency lighting wiring.
Possible Cause # 2: LED Damage
LEDs can be damaged by excessive vibration, humidity, and chemical or aerosol contamination.
In this case, you should make sure that the lamp is malfunctioning by installing it in a known working lamp with the power turned off.
Climatic and other equipment can create a vibration that can affect the LED if it occurs in close proximity to its housing. It is necessary to verify the presence of such an effect and eliminate or reduce vibration or increase the distance between its source and the lamp housing.
Damage caused by liquids, contamination with chemicals or aerosols can cause the LED to malfunction or fail. Their sources should be eliminated before attempts are made to eliminate the malfunction.
Possible reason # 3: LED damage for other reasons
Like any other light source, an LED lamp can fail as a result of physical impact, including accidental falling.
In addition, the LED may be damaged as a result of power surges that occur when it is connected when the power is on.
- In this case, you should make sure that the lamp is malfunctioning by installing it in a known-good housing with the power off.
- The luminaire must be checked for visible damage to the LEDs.
- When connecting the LED to the driver, make sure that the power is turned off.
Possible Cause # 4: Driver Damage
The LED driver has certain input parameters. Applying inappropriate voltage may damage it. Incorrect wiring and poor electrical connections can also damage the LED.
To fix the malfunction, check the input voltage of the driver (for example, 120 V), and then in the lamp (for example, 277 V). Mismatch is possible here.
It is necessary to try to install a faulty LED instead of a working one, without forgetting to turn off the power. If it does not light up, the reason lies in the LED lamp.
You should check all wires associated with the driver, including phase and zero, dimming circuit, emergency lighting , etc., and eliminate the identified malfunctions. If this does not help, then the driver is probably damaged. For this reason, contact the manufacturer.
Problem: LEDs turn yellow or discolour. Possible reason number 1: incompatibility between the LED and its power
The base of the LED lamp may not be compatible with the driver. For example, a 6-inch 10-watt LED is mounted in a 6-inch 15-watt socket.
Most LEDs of different capacities can fit the same housing size. However, the LED may not be compatible with the chassis driver, even if they fit together. It is necessary to consult the seller or the manufacturer on the issue of whether a particular LED is suitable for a particular housing. Otherwise, order new LEDs of the appropriate power.
Possible reason # 2: high ambient temperature
High ambient temperatures may occur. Heat is the enemy of LED technology and can significantly reduce lamp life. Weather or climate can play a significant role in hot, arid, desert areas and areas with a combination of high temperature and humidity.
To fix the problem, it is necessary to check the temperature near the lamp housing, below and above the suspended ceiling. If the ambient temperature constantly exceeds 50 ° C, the LED will be damaged and will not work as expected. This problem should be fixed by lowering the air temperature or moving the device. However, this will not return the LED to its previous state. Contact the manufacturer to replace the LED fixture.
Possible Reason # 3: End of Life
At the end of the lamp's life, the LEDs can change the glow temperature, color rendering rate and light output. This is a sign that the LED lamp may need to be replaced. In this case, contact the manufacturer.
Problem: Low Flicker LED Lights
Blinking light can cause eye fatigue and reduce performance. It is characterized by a coefficient and frequency.
The flicker coefficient of LED lamps is the ratio of the difference between the maximum and minimum illumination to their total. It can range from 0% for luminaires powered by a direct current source, to 100%. The coefficient value for incandescent lamps is 6–17%. According to the regulations, it should not exceed 20%.
The flicker frequency of LED lamps depends on the driver and is equal to 100 Hz for a conventional ballast. The optimal value of this parameter is above 300 Hz.
How to check the flickering of an LED lamp? There are several ways to do this:
- using the smartphone’s camera with the flicker suppression option turned on;
- taking a photo of the light source using the smartphone’s camera - the presence of darkened bands will indicate the presence of ripple;
- using a photodiode connected to a PC, multimeter or headphones;
- using a light meter to make such measurements;
- observing the stroboscopic effect of a fast moving object (for example, a ruler, pencil or yule).
You can eliminate LED flickering that is not associated with improper operation of the lamp in the following ways:
- use a source of really constant, not ripple current;
- Replace a high-flicker luminaire with a compliant LED lamp.