Document UT-MT-0779_EN
Page 15 of 37
Edition 23/04/2019
Supersedes edition 06/03/2019
LED INSET RUNWAY EDGE LIGHT LIRE
INSTRUCTION MANUAL FOR USE, INSTALLATION AND MAINTENANCE
2.3
ELECTRONIC SECTION
The electronic section consists of the following circuits:
Current / current conversion circuit
LED command circuit
Control circuit
2.3.1
Current / current conversion circuit (patented)
This electronic section provide a conversion from the input current value (within
range from 2.8 A to 6.6 A) to the specified LED current value.
This conversion, performed in one transformation only, allows to achieve several
benefits:
minimize the power losses
significant increase of efficiency
high input power factor
independent form the CCR topology: the CCR may have any output current
waveform
no percentage of load dependent: the CCR can feed without any problem also
few lights in the series circuit
isolation transformers of smaller size can be used, respect to those used with the
equivalent fixtures equipped with halogen lamps
The input circuit is protected against over-voltage, tested in accordance with the
requirements in FAA “Engineering Brief N°67” document.
2.3.2
LED command circuit
A PWM technique is used to command the LEDs. As known LEDs need to be supplied
with a constant current; therefore in order to vary the luminous emission with a
proper linearity is necessary the supply current will be applied at impulses. In other
words, the LED luminous output depends on the time of application (duty-cycle) of
constant current impulses.
2.3.3
Control circuit
The main task of the control circuit is to assure the correct LED light emission
according to the series circuit current.
To perform this features, the circuit is provided with a current sensor that generate a
signal proportional to the series circuit current.
This signal is analyzed by a DSP which perform a RMS conversion of the input current.
