Power saver device for public lighting systems and method thereof

Abstract

This invention is referred to an energy saving device which supplies the high efficiency sodium steam lamps and a method providing additional savings of electrical energy by means of the temporary reduction in the luminous flow of a high efficiency sodium steam lamp. The energy saving device includes in its operation protection against low voltage supply, regulation of supply voltage and protection in absence or damage of the lamp. In turn, the method includes a sequence for a reliable ignition of the lamp, a modulation routine in frequency for elimination of acoustic resonance and an automatic turn off sequence in view of damage of the photocell which is a consequence in this type of devices, as well as a consumption detection system to keep the output power steady and therefore, keep the power consumption under a steady value.

Description

INVENTION FIELD

This invention is related with the energy saving device used in public lightning systems, specifically, the invention is related with a device to supply high pressure sodium steam lamps and the method for saving electrical energy using said device.

BACKGROUND

Public lightning systems are one of the electrical loads consuming the highest level of energy, and therefore, any improvement to the efficiency of these systems results into a great saving of energy for the companies producing electrical energy, which results into less consumption of fossil fuel and less contamination. One of the most efficient sources currently known is the sodium steam lamps; its high efficiency is one of the main reasons why it is preferred in the public lightning systems. The combination of a sodium steam lamp along with an electronic ballast, result into a significant saving of electrical energy, and if a luminous intensity control reducing the energy consumption as the new day comes is added thereto, the result is a very important saving of energy regarding a conventional system using mercury steam lamps and with electromagnetic ballast.

Some energy saving devices use a micro controller for the control of the electronic ballast elements which supply the sodium steam lamp and allow greater flexibility for the control of the luminous intensity, the protections associated and the lightning process of the lamp, reducing in addition the number of necessary components and the size of the ballast. Said devices also allow the implementation of techniques for a simple elimination of acoustic resonances and without adding additional elements.

Generally, the sodium steam lamps require a lightning voltage above 2000 volts; in order to provide these voltage levels an igniter is usually used. The use of this additional component increases the ballast cost, hence, it is recommendable that the own ballast inversor is capable of providing these voltage levels. An alternative solution is to use a resonant tank which provides the sufficient voltage to light a lamp. Said resonant tank is capable of providing high voltage levels during very brief time. Now then, if said time is extended, the high currents involved in the lightning may damage the semiconductors devices of the inversor. This condition may occur if there is no lamp connected to the inversor or else if the lamp has just turned off and it is intended to immediately re-light it after turning it off. In order to avoid this damage, a protection is necessary which detects if the lamp has already lightened and if not, it deactivates the ballast.

Another risk condition of the energy saving devices is the electronic ballast supply as from very lower voltages than the nominal voltage; according to the standards, all electronic ballast include a correcting stage of the energy factor which provides a voltage level and continuous energy to the ballast inversor. If the supply tension falls below a critical level, the current requested by the energy factor corrector is increased at the same ration and it may damage the semiconductor devices of the corrector. Therefore, a protection deactivating the electronic ballast is necessary under low supply voltage conditions.

Ohkubo and Miyagaki proposed electronic ballast in U.S. Pat. No. 5,482,860, which includes a microprocessor which is mainly used to program a control Method preventing the acoustic resonant phenomenon. The disadvantage of the control method described in said patent consists in that the protection sequence or the lightning process of the lamp are not established.

Electronic ballast for high intensity discharge lamps capable of providing high voltage levels for lightning of the lamp is presented in U.S. Pat. No. 5,677,602, said ballast includes a protection to detect the lightning of the lamp. However, this protection uses an operational amplifier for the detection of current which increases the final product cost.

U.S. Pat. No. 6,137,240, discloses a control circuit for a universal ballast based on a micro controller, the ballast may turn on, stabilize and control the luminous intensity of the lamp, the ballast has a corrector of the energy factor based on an elevator converter and it establishes options to supply the micro controller as from the elevator converter. The above-mentioned control circuit presents the following disadvantages: programming of the micro controller does not include any action to eliminate the acoustic resonance phenomenon; it neither includes protection against lamp absence or protection of the elevator converter against supplying from alternate current (AC) sources of low voltage.

U.S. Pat. No. 6,329,761, discloses electronic ballast for high intensity discharge lamps allowing the control of luminous intensity and presents high energy factor. However, this invention does not use a micro controller and for the lightning of the lamp it uses a special circuit for this function which increases the number of components and its complexity and, therefore, the cost.

Notwithstanding the above-mentioned description in the technical field, there is still the need of an energy saving device for public lightning systems which is easy, efficient, it includes a luminous intensity control, low cost and that it exceeds the energetic savings provided by known systems.

PURPOSE OF THE INVENTION

In comparison with the above-described patents, the first purpose of the invention is to provide a device which allows the electric energy saving in public lightning systems based on the following actions:

a) Use of a discharge lamp of high luminance efficiency.

b) Use of high efficiency electronic ballast with a high energy factor which lightens the lamp without the need of an additional igniter.

c) An operation method consisting in the decrease of luminous intensity provided by the lamp at late hours at night, which may be comprised of attenuation, a number of attenuations or not attenuation.

d) Registration of output consumption, this is important since this type of lamps vary their consumption according to the temperature or aging thereof. Upon having closed loop supply, we may keep the exit energy steady regardless the temperature variations of the environment or the input voltage changes or the age of the lamp.

A second purpose is to provide the energy saving device of this invention with a micro controller which reduces the number of components and the cost of the energy saving device and so that, in comparison with the above-mentioned patents, it contains the programming of a method for the saving of energy which consists of all and every of the following:

a) Generate the control signals of the semi-conductors associated to the inversor.

b) Make a modulation of the operation frequency of the inversor circuit used for the elimination of the acoustic resonance.

c) Establish a sequence for the lightning of the lamp preventing the damage of the semi-conductors associated to the used inversor.

d) Vary the luminous intensity of the lamp and therefore, the energy consumption after a previously fixed operation time.

e) Detect the supply voltage of line to turn off the lamp in case of high or low voltage.

f) Register the consumption to keep steady energy regardless temperature changes, line voltage or aging of lamp.

g) Deactivate the used inversor operation upon not turning on or turning off the lamp.

h) Restart the used inversor operation after a fixed number of operation hours lapses.

Now then, by the use of a micro controller in the energy saving device of this invention, there is a significant reduction in the number of analogue components which would be necessary to make al the actions described in the second purpose, and since the micro controller has a very low cost, three is a substantial reduction in the cost of the energy saving device of this invention.

A third purpose is to provide the energy saving device of this invention with a circuit for the detection of the lightning of the lamp; in order to prevent damages in the used inversor semi-conductors said circuit protects the energy saving device of this invention against the damage in the lamp or against absence thereof.

Fourth purpose is to provide the energy saving device of this invention with a protection against high or low voltage of the alternate current (AC) supply source which is also registered by the micro controller which prevents damage due to over voltage in the corrector semi-conductors of the energy factor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 presents the block diagrams of the energy saving device for public lightning systems according with this invention.

FIG. 2 corresponds to the corrector diagram of the energy factor used in the device of this invention.

FIG. 3 shows the resonant inversor diagram used as inversor in the energy saving device for public lightning systems and a resistance allowing the registration of the current for supply and control by the closed loop.

FIG. 4 presents the scheme proposed for the detection of the lightning of the lamp.

FIG. 5 corresponds to the connections diagram of the micro controller which includes the protection against low voltage in the supply used in the energy saving device of this invention.

FIG. 6 shows the connections diagram of the driving circuit used for handling of the inversor switches.

FIG. 7 shows a diagram of the low voltage supply source for monolithic integrated circuits.

FIG. 8 shows the flow chart of the micro controller programming used in the energy saving device for public lightning systems.

FIG. 9 shows an operation graph of the ballast with an attenuation level.

FIG. 10 show an operation graph of the ballast with double attenuation.

FIG. 11 shows an operation graph of the ballast without attenuation.

DETAILED DESCRIPTION OF THE INVENTION

Regarding FIG. 1, the energy saving device for public lightning systems (1), subject matter of the invention, may be observed in FIG. 1 and that it is comprised of the following components:

A corrector converter of the energy factor (2), based on an elevator converter; a resonant invertor (3), the preferred embodiment of this circuit for this invention is an amplifier class (D); number (4) represents a high efficiency sodium steam lamp; number (5) represents a circuit for the detection of the lightning of the high efficiency sodium steam lamp (4); number (6) represents a micro controller; number 21 represents a sensor for the energy consumption; number (7) represents a driver for the switches handling; number (8) represents the supply circuit for the digital and control stages and number (9) represents a circuit for the protection against low voltage of the energy saving device (1), now then, the corrector converter of the energy factor (2) is shown in FIG. 2, this converter (2) is in charge of correcting the energy factor of the energy saving device (1) so that it is close to the unit, a second function of the converter (2) is to provide a steady voltage level to the resonant inversor stated under number (3).

FIG. 3 shows the resonant inversor (3) which is used to supply the high efficiency sodium steam lamp (4), in this circuit the voltage provided by the terminal (15) is cut by means of switches (17) and (18), thus generating a unipolar squared wave; the control signals stated with numbers (19) and (20), of the switches (17) and (18) are provided by the driver (7), which is illustrated in FIG. 6, this signal is applied to the resonant tank formed by the capacitor (22), the inductor (23) and the capacitor (24), which filters the fundamental component of this signal and it applies it to the high efficiency sodium steam lamp (4), the voltage component of the unipolar squared wave is filtered by the capacitor (22), for a greater stability of the current of the high efficiency sodium steam lamp (4); the operation frequency, once the high efficiency sodium steam lamp (4) is turned on, is always lower than the resonance frequency with the high efficiency sodium steam lamp (4) on, which guarantees an inductive behavior of the resonant tank. When there is an inductive behavior, it is observed that: the higher the frequency the lower is the energy supplied to the high efficiency sodium steam lamp (4) and at lower frequency the energy in the high efficiency sodium steam lamp (4) is increased. These operation conditions allow the control of the energy in the high efficiency sodium steam lamp (4) varying the operation frequency of the resonant tank and therefore, control the luminous intensity of the high efficiency sodium steam lamp (4). However, upon decreasing with this method the energy supplied to the high efficiency sodium steam lamp (4), there is the risk that for low energy, the electric arch in the high efficiency sodium steam lamp (4) is extinguished. In order to avoid this risk, a resonant tank is designed so that it supplies the minimum intended energy to the high efficiency sodium steam lamp (4). In this way, it is guaranteed that for this minimum energy the electrical arch does not extinguish. Further detail for the design process of a resonant tank to a given energy of the high efficiency sodium steam lamp (4) may be found in the Article “A Comparison of LCC and LC Filters for its Application in Electronic Ballast for Metal-Halide Lamps” by J. Correa, et al, published in IEEE ENERGY Electronics Specialist Conference (PESC) held in Vancouver (Canada), June 2001.

In the energy saving device (1) of this invention, the resonant tank is also used for lightning the high efficiency sodium steam lamp (4), hence, a frequency scan is made by means of the micro controller, stage (65) of the signal applied to the tank, in such a way that the resonant frequency is in this scan. The purpose of the frequency scan is that the unipolar squared signal frequency applied to the resonant tank matches with the frequency of the tank despite the variations in the values of its elements due to the tolerance thereof. Further detail on the lightning process is provided in the description of FIG. 8.

FIG. 4 shows a circuit for the detection of lightning (5) of the high efficiency sodium steam lamp (4), in said circuit (5), the current through the high efficiency sodium steam lamp (4) is detected by means of a voltage current transformer (25), the alternate voltage in the terminals of the secondary of the transformer (25) is rectified by the diode (26); in this way, the secondary of the transformer (25) only applies positive voltage pulses between the base and the transmitter of the PNP transistor (27), to avoid electromagnetic noise signals during the negative pulses in the transformer (25), the diode (28) circuit breaks the secondary of the transformer (25). The positive pulses polarize the transistor (27) taking it to saturation. Upon said transistor being saturated (2) it behaves as a closed switch, therefore, the voltage of the terminal (29) is applied in the terminal (30), the voltage in the terminal (30) is sent in turn to the micro controller (6) indicating it that the high efficiency sodium steam lamp (4) is on. Resistance (31) acts to limit the base current in the transistor (27), and resistance (32) acts as fastening of the transistor base (27) to the terminal (29) to avoid it is floated when there is no current to the high efficiency sodium steam lamp (4). Capacitor (33) stores part of the pulsing energy supplied by the transformer (25) thus helping to keep the transistor (27) continuously saturated while there is current to the high efficiency sodium steam lamp (4).

FIG. 5 shows the connections diagram to the micro controller (6) used in the energy saving device (1), which is comprised by 8 terminals; terminal (29) supplies the circuit, terminal (34) detects the line voltage for turning off in high or low voltage (9), which comes from a voltage divisor formed by some resistances (40) and (41), terminals (35), (36), (30), (37), (38) which are five in and out ports and terminal (16) which is the ground connection of the micro controller (6). The terminal port (30) is used to detect the lightning of the high efficiency sodium steam lamp (4), port of terminal (36) is used to send the control signal to the switches (17) and (18), port terminal (35) sends the deactivation signal to the resonant inversor (3) in absence of current to the high efficiency sodium steam lamp (4) or when there is low line voltage, terminal (38) is the reference to ground for terminal (39), terminal (39) detects the consumed current for lamp (4) already converted into voltage by the resistance (21) an divided by resistances (42) and (43) so that the measured voltage rank is in the values handled by the micro controller (6), all this so that the micro controller (6) has a closed loop control and keeps the energy consumption steady.

FIG. 6 shows the driving circuit (7) used in the energy saving device (1) of this invention, said circuit) (7), receives the control signal sent from the corresponding micro controller port (6) to the terminal (36) and it divides it into two out of phase signals of 180 degrees, terminals (19) and (20), these two signals are conditioned to a suitable voltage level for the lightning of the switches (17) and (18) and with the separation off time between each one of them to prevent simultaneous lightning of switches (17) and (18).

FIG. 7 shows the supply circuit of 5 volts of direct current for the micro controller (6) and 15 volts of direct current for the corrector (10) and the driver (7) which has a transformer (46) for the galvanic isolation and voltage reducer, a full wave rectifier (47), a voltage regulating circuit at 15 volts current (48), and a voltage regulating circuit at 5 volts current (49).

FIG. 8 shows the flow chart of the energy saving method of the energy saving device (1) of this invention and that it is part of the micro controller programmer (6). The stages of said method are the following: a calibrating routine of the internal clock is established in the stage (69), the corresponding in and out ports are to the terminals (39), (40), (34), (41), (42) and the internal clocks of the micro controller (6) configured.

There is a waiting period from 5 to 10 seconds to allow the generation of the start-up pulses in the state (70), since if there has been a black out or a lamp has turned off (4), said lamp does not try to immediately turn on, since it will be hot and the lamp (4) will not turn on, thus, it will be worn out due to many failed attempts to turn it on, in this way, there will be a waiting period from 5 to 10 seconds between each attempt to turn on the lamp.

Stage (71), consists of making a frequency scan from 95% of the vacuum resonant frequency of the resonant tank formed by the capacitor (22), the inductor (23) and the capacitor (24) until 105% of the resonant frequency, in this way, it is guaranteed that despite the capacitor (22) tolerance and the capacitor (24) and the saturation effects of the inductor (23), one of the scan frequencies will be equals to the vacuum frequency of the resonant tank.

The following stage (72) consists in verifying the terminal (30) status of the micro controller (6), if the terminal (30) is the same as one logic then the high efficiency sodium steam lamp (4) indeed turned on and it goes to stage (75); if the terminal (30) is the same as a zero logic, then the high efficiency sodium steam lamp (4) did not turn on. If the high efficiency sodium steam lamp (4) did not turn on, stage (73) shall apply.

Stage (73) is a routine which purpose is to try to re-ignitiate the high efficiency sodium steam lamp (4) in a failed attempt to turn it on in stage (72). The purpose of this re-ignition sequence is to apply high voltage peaks to the high efficiency sodium steam lamp (4) for the ignition thereof during eight or more times at twenty-seconds intervals between each impulse (70), in this way it is possible to re-ignitate the high efficiency sodium steam lamp (4) after a black out has occurred and it also enables to turn on the old high efficiency sodium steam lamp (4). The above is attained by means of the application to the high efficiency sodium steam lamp (4) of two or more consecutive high voltage peaks (72), all of the above without damaging the switches (17) and (18). If once the re-ignition routine is applied to the high efficiency sodium steam lamp (4) it still remains turned off, there are two cases: the first one is that one of the high efficiency sodium steam lamp (4) is not connected to the energy saving device (1), the second case is that the connected high efficiency sodium steam lamp (4) is already too old and it is not possible to turn it on, therefore, it is applicable in both cases to deactivate the used inversor (3), stage (74) in FIG. 8, it is important to highlight that if the high efficiency sodium steam lamp (4) turns on, stage (75) will apply.

Stage 75, consists in applying an increased scan in the switching frequency of the used inversor (3) from 90% to 93% of the nominal frequency of operation up to 107% to 110% of the nominal frequency of operation and afterwards a decreased scan from 107% to 110% of the nominal frequency from 90% up to 93% of the nominal frequency, the frequency increments of these increased and decreased scans is from 200 HZ to 300 HZ. The purpose of these scans is to avoid the occurrence of an acoustic resonance phenomenon in the high efficiency sodium steam lamp (4).

During each one of the frequency scans of stage (75), stage (76) must apply at all times, which consists in counting the time lapsed from the ignition of the high efficiency sodium steam lamp (4) until the time it reaches (51) FIG. 9 or T2 and once said period of time is concluded stage (77) is applicable and if it has not been reached yet, stage (75) applies and so forth.

Stage (77) consists in decreasing the power to a specific percentage varying the medium of the frequency and sensing (21) the power until obtaining the scheduled result. An increased scan is applied to this section in the switching frequency of the used inversor (3) from 92.5% of the nominal frequency of operation up to 107.5% of the nominal frequency of operation and afterwards a decrease scan from 107.5% of the nominal frequency of operation up to 92.5% of the nominal frequency of operation, the increments of frequency of these increased and decreased scans is from 200 HZ to 300 HZ, the medium frequency of these scans will depend on the power percentage required to obtain the high efficiency sodium steam lamp (4). The purpose of these scans is to prevent the occurrence of the acoustic resonance phenomenon in the high efficiency sodium steam lamp (4).

During each one of the frequency scans of stage (77), stage (78) applies at all times which consists in counting the time lapsed from the ignition of the high efficiency sodium steam lamp (4) until the moment it reaches (52) FIG. 9 or T2 and once said period of time is concluded, stage (79) applies, and if it has not been reached yet, stage (77) applies and so forth.

Stage (79), (which applies only when there is double attenuation) consists in decreasing the power again in a specific percentage (57), varying the medium of the frequency and sensing (21) the power until reaching the scheduled result (74). Increased scan is applied in this section in the switching frequency of the inversor used (3) from 92.5% of the nominal frequency of operation up to 107.5% of the nominal frequency of operation and afterwards a decreased scan from 107.5% of the nominal frequency of operation up to 92.5% of the nominal frequency of operation, the frequency increments of these increased and decreased scans is from 200 HZ to 300 HZ, the medium frequency of these scans will depend on the power percentage required for the high efficiency sodium steam lamp (4). The purpose of these scans is to prevent the occurrence of the acoustic resonance phenomenon in the high efficiency sodium steam lamp (4).

During each one of the frequency scans of stage (79), stage (80) applies at all times, which consists in counting the time lapsed from the ignition of the high efficiency sodium steam lamp (4) until the moment it reaches (53) FIG. 10 or T3 and once said period of time is concluded, stage (81) applies and if it is not reached yet, stage (79) applies and so forth.

Stage (81), (which applies only when there is double attenuation) consists in increasing the power in a specific percentage varying the frequency means and sensing (21) the power until reaching the scheduled result. Increased scan is applied in this section in the switching frequency of the used inversor (3) from 92.5% of the nominal frequency of operation up to 107.5% of the nominal frequency of operation and afterwards a decreased scan from 107.5% of the nominal frequency of operation up to 92.5% of the nominal frequency of operation, the frequency increases of these increased and decreased scans is from 200 HZ to 300 HZ, the medium frequency of these scans will depend on the power percentage required for the high efficiency sodium steam lamp (4). The purpose of these scans is to prevent the occurrence of the acoustic resonance phenomenon in the high efficiency sodium steam lamp (4).

During each one of the frequency scans of stage (81), stage (82) applies at all times, which consists in counting the time lapsed from the ignition of the high efficiency sodium steam lamp (4) until the time it reaches (62) FIG. 10 or T4 and once said period of time concludes, stage (83) applies and if it has not been reached yet, stage (81) applies and so forth.

Stage (83), (which applies only when there is double attenuation) consists in increasing the power in a specific percentage varying the frequency means and sensing (21) the power until reaching the scheduled result. Increased scan is applied in this section in the switching frequency of the used inversor (3) from 92.5% of the nominal frequency of operation up to 107.5% of the nominal frequency of operation and afterwards a decreased scan from 107.5% of the nominal frequency of operation up to 92.5% of the nominal frequency of operation, the frequency increases of these increased and decreased scans is from 200 HZ to 300 HZ, the medium frequency of these scans will depend on the power percentage required for the high efficiency sodium steam lamp (4). The purpose of these scans is to prevent the occurrence of the acoustic resonance phenomenon in the high efficiency sodium steam lamp (4).

During each one of the frequency scans of stage (83), stage (84) applies at all times, which consists in counting the time lapsed from the ignition of the high efficiency sodium steam lamp (4) until the time it reaches (68) FIG. 10 or T5 and once said period of time concludes, stage (85) applies and if it has not been reached yet, stage (83) applies and so forth.

If due to a malfunction of the photocell, said photocell does not cut the energy supply and the energy saving device (1) continues working, stage (84) will apply, during said stage the time lapsed would continue being counted and upon reaching a previously fixed time (T5) (68), the used inversor would be deactivated (3), turning off the high efficiency sodium steam lamp (4), stage (85) to prevent the energy consumption during the day.

Once the high efficiency sodium steam lamp (4) is turned off, the energy saving device (81), will continue operating but with the turned off inversor (3), the time will continue being counted by the micro controller (6) until reaching stage (85). It is verified during this stage if the counted time has reached 24 hours (one day) if so, stage (71) would apply repeating all the process again, and if the time has not reached 24 hours, then stage (85) is maintained.

FIG. 9 shows the operation of the energy saving device regarding the power consumption vs. time in operation mode of one attenuation. The device works at nominal power of the lamp (4) at the start point during a specific period of time (T1) (50), then the device attenuates the power consumption at a specific percentage regarding the nominal power (% PN) (53) during a specific time (T2) (51), returning to its nominal power at the end of the operation sequence with a given duration (T3) (52).

FIG. 10 shows the operation of the energy saving device regarding the power consumption vs. time in operation mode of double attenuation. The device works at nominal power of the lamp (4) at the start point during a specific period of time (T1) (55), secondly, the device attenuates the power consumption at a specific percentage regarding the nominal power (% PN) (61) during a specific time (T2) (56), in the third step the systems attenuates again the consumption (% PN)((59) during (T3)(57), returning to the first attenuation level (% PN) (61) with a duration of (T4) and finally, returning to its nominal power to end the operation sequence with a given duration (T5) (68).

FIG. 11 shows the continuous operation mode wherein the device keeps the lamp (4) operating at its nominal power (64) all the time (T1)(63).

Claims

1. Energy saving device for public lightning systems comprising: a corrector converter of the power factor (2), which provides a continuous voltage level to the resonant inversor (3), which regulates the supply voltage variations and that presents a power factor to the electrical network higher or equals than 98 percent, the resonant inversor (3) has a resonant tank formed by inductors and capacitors which turns a continue current signal into an alternate squared signal or unipolar signal which frequency is higher or the same than 1 Khz wherein the squared signal is filtered by the resonant tank formed by an inductor (23) and two capacitors (22) and (24); a luminic high efficiency sodium steam lamp (4) presenting effectiveness higher than that of the conventional sodium steam lamps of equivalent power, a micro controller (6) which comprises an integrated circuit of 8 or more terminals, which programs a method that determines de operation of the energy saving device 81), a driving circuit (7) which comprises an integrated circuit receiving the control signal sent by the micro controller (6), and it conditions it to a suitable voltage level for the ignition and turning off of the switches (17) and (18) which includes the resonant inversor (3) characterized because the corrector converter of the power factor (2), includes a corrector integrated circuit of the power factor (10), and the resonant inversor (3) has a class amplifier (D) and a resonant tank LCC, in addition to a circuit which fees the high efficiency sodium steam lamp (4) and applied to said lamp (4), once said lamp (4) turned on a signal which frequency is always lower than the resonance frequency of the resonant tank formed by the capacitor (22), inductor (23) and the capacitor (24) with the high efficiency sodium steam lamp (4), likewise, it includes a circuit for protection against high voltage (9) of the in tension which is the one detecting the rectified line voltage (13) by means of a resistant divisor formed by resistances (40) (41), and in which the voltage in the resistance terminals (41) is filtered and converted into a direct current level by means of a capacitor (45) and that it is designed so that in the case the alternate current supplying voltage varies certain percentage out of the nominal power both in high and low voltage, the value is detected by the micro controller (6) and this turns off the resonant inversor (3) that in turn it will turn off the lamp (4), thus preventing damages to the energy saving device (1) in one of its parts, reestablishing the normal ignition operation and work once the voltage is under the operation ranks.

2. Energy saving device for public lightning systems in accordance with Clause 1, characterized in addition, because the resonant inversor (3) regulates the nominal frequency of operation increasing it as from 90 up to 93 percent of the nominal frequency of operation from 107 to 110 percent of said nominal frequency.

3. Energy saving device for the public lightning systems in accordance with Clause 1 characterized in addition because the resonant inversor (3) reduces the nominal frequency of operation from 107 to 110 percent up to 90 to 93 percent of the nominal frequency of operation.

4. Energy saving device for public lightning systems in accordance with clause 1 characterized in addition because the frequency jumps for the scan in the resonant inversor 83) supplying the lamp (4) is from 200 HZ to 300 HZ.

5. Energy saving device for public lightning systems in accordance with Clause 1 characterized in addition because the corrector converter of the power factor (2) works at the division between the continuous conduction mode and de discontinued conduction mode.

6. Energy saving device for public lightning systems in accordance with Clause 1 characterized in addition because the resonant inversor (3) applies to a luminous intensity control of the high efficiency sodium steam lamp (4) which is accomplished by varying the switching frequency of the resonant inversor (3).

7. Energy saving device for public lightning systems in accordance with Clause 1, characterized in addition because the resonant inversor (3) includes a tank comprising a capacitor (22), an inductor (23) and one capacitor (24) designed to provide the minimum sufficient power to turn on the high efficiency sodium steam lamp (4).

8. Energy saving device for public lightning systems in accordance with Clause 1, characterized in addition because it comprises a circuit for ignition detection (5) of the high efficiency sodium steam lamp (4) and said circuit detects the current through the high efficiency sodium steam lamp (4) by means of a voltage current transformer (25) in which the alternate voltage in the terminals of the secondary is rectified by a diode (26), the current provided by said rectified voltage is limited by the resistance (31) and injected to the base of the transmitter PNP (27), which upon saturation it works as a closed switched which applies a logic in the terminal (30) of the micro controller (6), and in which diode (28) circuit breaks the transformer (25) and in which one resistance (31) acts to limit the base current of the transmitter (27), in said circuit the resistance (32) acts as fastening of the terminal (29) to the transistor base (27) to prevent it remains floated when there is no current in the high efficiency sodium steam lamp (4) and the capacitor (33) stores part of the pulsing energy provided by the transformer (25) keeping the transistor (27) continuously saturated while there is current to the high efficiency sodium steam lamp (4), in addition, the micro controller (6) for the energy saving device is formed by eight terminals, terminal (29) supplying the circuit, terminal (34) detecting the line voltage to turn off the high or low voltage (9) which comes from a voltage divisor formed by some resistances (40) and (41), terminals (35), (36), (30), (37), (38), which are five in and out ports and terminal (16) which is the ground connection to the micro controller (6).

9. Method for energy saving in public lightning systems comprising the following stages a) select among three operation modes of the high efficiency sodium steam lamp (4), each operation mode applies to a different device characterized because in case 1 figure (9), the high efficiency sodium steam lamp (4) is operating at a nominal power (65) during a prefixed number of hours T1 (59) and reducing the power supplied to the high efficiency sodium steam lamp (4) to a medium percentage (% PN) of its nominal value, once this time T1 (59) has lapsed and then once time T2 (51) has lapsed, it returns to its nominal power (65) of the high efficiency sodium steam lamp (4), concluding with an automatic turn off when the total time is reached; case 2 figure (10) consists in the operation of the high efficiency sodium steam lamp (4) to a nominal operation power (67) during a prefixed number of hours T1 (55), and reducing the power supplied to the high efficiency sodium steam lamp (4) to a medium percentage (%) PN of its nominal value once the time T2 (56) has lapsed reducing again the power supplied to the high efficiency sodium steam lamp (4) to a percentage under (% PN) (59) of its nominal value once this time T3 (57) has lapsed, returning to its medium power (% PN) (61) of the lamp, and once this time T4 (62) has lapsed, it returns to its nominal power (67) of the lamp, concluding with an automatic turn off when the total time is reached; wherein in addition, the method for saving energy in public lightning systems in case three FIG. 11), comprises the operation of the high efficiency sodium steam lamp (4) at its nominal power (64) during all the operation time (63); consisting in: a) the ignition of the high efficiency sodium steam lamp (4) by means of frequencies around the vacuum resonant frequency of the resonant tank of the used inversor (3), b) modulation of the switching frequency of the used inversor (3) to prevent the occurrence of the acoustic resonance phenomenon in the high efficiency sodium steam lamp (4), c) keep the steady consumption of the power, by means of a sampling supply system of closed loop consumption to the micro controller (6) which will regulate the output power.

10. Method for energy saving in public lightning systems in accordance with Clause 9 characterized in addition because the modulation stage of the frequency is accomplished by means of an increased scan in the switching frequency of the used inversor (3) from 90 to 93 percent of the nominal frequency of operation up to 107 to 100 percent of the nominal frequency of operation and ten a decreased scan from 107 to 110 percent of the nominal frequency up to 90 to 93 percent of the nominal frequency of operation in maximum steps of 1 percent of the nominal frequency; the frequency steps applied to these increased and decreased scans are from 200 HZ to 300 HZ.

11. Method for energy saving in public lightning systems in accordance with Clause 9, characterized because it comprises the stage of ignition attempts or re-ignition of the high efficiency sodium steam lamp (4), in view of hot ignition situations or a failed ignition, said stage consists in applying impulses, each one consisting in the application of the ignition stage during eight or more continuous times, lapse between each impulse should be 5 seconds or more.

12. Method for energy saving in public lightning systems in accordance with Clause 11 characterized in addition because it comprises the definitive deactivation stage of the inversor (3), if upon concluding the ignition attempts stage or re-ignition stage of the high efficiency sodium steam lamp (4), it does not turn on.

13. Method for energy saving in public lightning systems in accordance with Clause 9 characterized in addition for the turn off stage of the high efficiency sodium steam luminic lamp (4), once the total time or less than 24 hours has lapsed.

14. Method for energy saving in public lightning systems in accordance with Clause 9, characterized in addition by the ignition stage of the high efficiency sodium steam luminic lamp (4), once 24 hours have lapsed.

15. Method for energy saving in public lightning systems in accordance with Clause 9, characterized in addition because the ignition stage of the high efficiency sodium steam lamp (4) comprises a frequencies scan from 95 percent of the vacuum resonant frequency in the resonant tank formed by the capacitor (22), inductor (23) and the capacitor (24) up to 105 percent of this resonant frequency.

16. Method for energy saving in public lightning systems in accordance with Clause 9, characterized in addition because the modulation stage of the switching frequency of the inversor (3) is accomplished by means of a sinusoidal modeling, triangular, squared or exponential signal.

17. Method for energy saving in public lightning systems in accordance with Clause 9, characterized in addition because the modulation stage of the frequency comprises an index value of the modulation of the modulating signal between 5 and 50.