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Lighting loads control
Lighting loads are defined by the energy used to operate electric lighting, most commonly in commercial and public buildings. However, they can be quite complex to control as they can be either inductive or capacitive.
How to control different lighting loads
Dimmers
A dimmer is a type of control device that allows the lighting to be adjusted from zero to full power. Dimming is achieved by changing the voltage applied to the light. The type of dimmer depends on the type of load or lamp. Dimming is not suitable for every type of lamp load. For example, it is not suitable for fluorescent lamps.
AC-55a loads (discharge lamps)
Discharge lamps have a high inrush current when switched on (approximately 10 to 25 times the rated current under certain conditions). So solid-state relays are well suited to controlling this type of load.
celduc® relais’ selection :
AC-55b loads (incandescent and fluorescent lights)
Incandescent lamps are commonplace in many homes and businesses, but few people are aware of the complex control systems that are at the heart of their operation. The inrush current characteristics of this load are similar to the surge characteristics of the thyristors used in AC solid-state relay outputs, making them the best choice for this application.
The most common method of dimming incandescent lamps is phase control. This technique involves interrupting the AC waveform so that only part of each half-cycle reaches the lamp. Brightness is then controlled by varying the time after zero-crossing at which the waveform is turned on or off. Random solid state relays are also used in high-power dimmers.
Control systems also use pulse width modulation (PWM) (917-4775) to control the brightness of an incandescent lamp. This involves rapidly switching the bulb on and off at a very high frequency (invisible to the human eye). By varying the duration of each pulse, the control system can effectively adjust the amount of time the bulb is on without affecting the overall brightness.
celduc® relais’ selection :
- The SO8 series (499-0525) (zero-cross single phase)
- The SGT8 series (three-phase)
- The SO7 series (917-4784) (random single phase)
- The SG4 series (231-1043) (phase angle controllers)
LED loads
The control of LEDs is not as easy as the control of incandescent lamps. All filament lamps can be dimmed without the need for any additional circuit. LEDs, however, vary in terms of dimming performance and control compatibility and require additional information before an LED lamp can be successfully controlled.
celduc® relais’ selection :
- The SKA series (231-0933) (PCB mounting)
- The SU8 and SO8 series (499-0525) (zero-cross single phase)
Open load detection
Open load detection can detect faulty modules or broken wires, but not partial failures. Many applications use multiple parallel strings of LEDs. Therefore, even if the rest of the strings are working, it is important to detect if any of the LED strings in the array are not working. By using accurate load current measurement, the celduc ESUC current monitoring module (702-6810) can identify this problem by detecting a clear change in output current due to a partial open caused by a string failure.
With over six decades of experience in the solid-state relay market, celduc® relais ensures the highest reliability in its French factory.
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