When installing LED lamps in place of halogen, it is often necessary to replace the old power source. Halogen lamps are connected to 12V electric transformers; LED lamps require the installation of special power supplies that have a similar output voltage. In this regard, it is important to understand whether it is possible to use an old transformer or whether to change it.
What is an electronic transformer
An electronic transformer is a switching power supply circuit based on a high-frequency generator operating on semiconductor switches and the transformer itself. The power of such a circuit is provided by a standard AC network with a voltage of 220V, but at the output the effective value is in the region of 12V. First, power from the mains is supplied to the rectifier, and then the rectified voltage is sent to the generator and power switch assembly.
A standard implementation of such a scheme is the use of a push-pull type oscillator, the key feature of which is the lack of the need for any special switching power supplies like PWM controllers. The automatic generator in this case switches the transistor under the influence of voltages that are induced on the transformer windings, and also provides positive feedback.
To ensure the normal operation of LED lamps, you will need any source that provides a stable 12V voltage on an ongoing basis and minimizes ripple. For this, the above-mentioned ICs are most often used.
Both schemes provide for the use of an integrated PWM controller, which ensures the adjustment of the operation of bipolar or field effect transistors. In addition, the output stage of the circuit includes a rectifier, as well as capacitors, which provide smoothing of the pulsations - they act as a kind of filter.
The result is a stabilized power source, the ripple of which corresponds to the current load, as well as the capacitance of the filtering capacitors. If necessary, it can be implemented on a self-generating circuit by analogy with an electronic transformer, using additional feedback circuits to provide the necessary stabilization of the output voltage.
Why you can not use ET with LED lamps
There are five reasons why LED lamps cannot be powered using standard electronic transformers:
- LED lamps require a constant voltage, due to their non-linear current-voltage characteristic and sensitivity to any deviations from the nominal voltage indicator. At the slightest excess, such lamps as a result can quickly fail.
- Electronic transformers are sources of AC voltage with a high frequency, and bursts and peaks in some situations reach 40V, which often leads to a complete failure of the LEDs or drivers used in the construction of modern LED lamps. In addition, a similar approach is fraught with their unstable work.
- Electronic transformers are distinguished by the presence of a minimum load in them.Thus, if the load of the connected lamp does not reach the level indicated on the power supply, the transformer may not start working at all, or it will work with increased ripple, turn off. This is a critical point, since the power consumption of halogen lamps significantly exceeds that of LEDs.
- Power supplies designed for power supply of LED lamps provide a stable and constant voltage.
- Halogen lamps are not picky about whether direct or alternating current flows through the network. The role is played only by his tension. In this regard, they can be connected to any power source.
Classic electronic transformers cannot be used as a power source for any LED lighting fixtures. When replacing the lamps, it will be necessary to select a special unit that provides stabilized voltage. If you ignore this, you may encounter premature failure of all lamps.
A step-down transformer
The standard life of LED lamps in accordance with the specifications declared by the manufacturers is 4000 working hours. If you do not use specialized step-down transformers in the operation of such devices, leaving the diode as the basis for operation, the operation period is reduced to 1200 hours of uninterrupted operation.
If the lamps are installed in rooms with a high concentration of moisture or constant temperature changes (saunas, pools), you need to use a special step-down transformer equipped with protection from water. It is also important to make sure that the total load of LED lamps is within 60%.
How to choose
There is nothing complicated in choosing a step-down transformer for LED lamps. If you encounter any difficulties, you can always consult with managers of companies that sell such equipment. The most important thing is to correctly calculate the power.
The sum of all LED lamps installed in the room is calculated, 20% is added to the result, since in the predominant majority of cases, only one transformer is used.
For example, there will be six 12V lamps in the room, their sum is 72V. Devices rated 60V can no longer be used. You need to purchase equipment at 100V or reduce the number of light sources. If you put a powerful transformer, you can add another lamp.
Savings do not depend on the power of the light sources used, but on the voltage. It is provided through the use of a transformer, which significantly increases the life of LED lamps.
Installation Features
The transformer is a portable device, but this type of installation is not suitable for everyone, because I do not want to spoil the interior with additional equipment. To hide such a device and at the same time ensure normal interaction with it will not be difficult if the house has suspended ceilings or false walls.
Ideally, the devices are mounted on a concrete slab. To provide easy access to them, a small hatch is made in the surface of the wall or ceiling. It should be noted that over time the device will need to be changed, so the mortise hole should correspond to its dimensions.
The decision to hide the transformer in the pantry is not always advisable, especially if several devices will be installed. No more than 2 meters of wire should go to the load source, so it will not work to position the transformer far from the lamp. To avoid all these problems, it is recommended to buy lamps with a built-in transformer.
The transformer heats up during operation
If you bought a new transformer, which after connecting and turning on began to heat up very much, you need to carry out several operations:
- Check the energy consumption load in the room and the correspondence of the permissible rating of the transformer to the number of lamps connected to it.
- Check the wiring of outlets and lighting in groups.
- Check if the load is on the device.
- View reviews on the Internet for the purchased device. It is possible that a low-quality transformer was purchased.
If a transformer that has been used for several years is heating up, this is an indicator of equipment wear. You should change it to a new one. It is better not to ignore these signals, as you may encounter flashing of the case, and this will create a risk of a fire hazard.
