Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/24—Circuit arrangements in which the lamp is fed by high frequency ac, or with separate oscillator frequency
  • H05B41/245—Circuit arrangements in which the lamp is fed by high frequency ac, or with separate oscillator frequency for a plurality of lamps
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
  • H05B41/14—Circuit arrangements
  • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
  • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
  • H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
  • H05B41/285—Arrangements for protecting lamps or circuits against abnormal operating conditions
  • H05B41/2858—Arrangements for protecting lamps or circuits against abnormal operating conditions for protecting the lamp against abnormal operating conditions

Definitions

• the invention relates to a method for feeding a UV light low-pressure lamp according to the preamble of claim 1 and a ballast for feeding a UV light low-pressure lamp according to the preamble of claim 7.
• UV lamps Ever more powerful low-pressure UV lamps are used in water disinfection using UV light. The requirements for efficiency and controllability are very high.
• the advantage of operating with a frequency that is significantly higher than the usual mains frequency is that the passive components used, such as inductors and capacitors, can be designed to be smaller in size and weight.
• the ionization of the remains after the zero crossing of the radiator current when the polarity changes Received gas discharge column, while it is interrupted at the usual mains frequency at each zero crossing of the lamp current by recombination of the ions, so that the UV light low-pressure lamp must re-ignite after each zero crossing.
• the disadvantage is the interference radiation and the line losses in the case of longer line lengths between the ballast and the UV light - low-pressure lamps. Both disadvantages are essential in water disinfection. Because with increasing UV light output, the interference radiation increases. Furthermore, entire batteries of UV light low-pressure lamps are used in a confined space, especially for water disinfection. If it is not possible to arrange the ballasts in this confined space, long supply lines must be accepted.
• the invention has for its object to simplify the supply during operation of UV light low-pressure lamps, to increase the UV light yield and to increase the efficiency without limiting the service life.
• a partial solution of the method according to the invention consists, in a manner known per se, of operating the UV light low-pressure lamps with direct voltage or direct current.
• a direct voltage operation with polarity reversal from time to time with the time intervals known from gas discharge lamps for lighting purposes would require a renewed preheating of the electrodes in UV light low-pressure lamps after each polarity reversal. Reversing the polarity with preheating every 15 to 30 minutes would severely limit the service life. Since UV light low pressure lamps for water disinfection using UV light generate significantly higher radiation powers than gas discharge lamps for lighting purposes and therefore significantly higher currents flow, the electrophoresis effect would set in much earlier.
• the remedy from the described dilemma is provided only by the further measure according to the invention of dimensioning the time periods for the polarity reversal shorter than a time resulting from the thermal time constant of the UV light low-pressure lamp until a lower limit value for the operating temperature of the electrodes is reached. If this design rule is observed, namely the electrode that is cooling at the time of the polarity reversal is still at the operating temperature and can then take over the function of the electrode previously kept at the operating temperature after polarity reversal without renewed preheating or wear due to increased current load.
• the advantages of direct current operation are used and the effects of electrophoresis and electrode wear due to excessive preheating or current load on the electrode, which has already cooled below operating temperature, are avoided.
• Switching the polarity is not a conventional AC operation, because the switching frequency per unit of time is lower than in AC operation with the previously lowest operating frequency, namely the mains AC voltage of 50 to 60 Hz.
• the switching of the polarity does not correspond to the zero crossing of the harmonic, especially sinusoidal Vibration of the AC mains voltage, but the polarity change of a voltage which takes place in the transition period of the switchover and which has at least the value of the operating voltage. Otherwise, the UV light low-pressure lamp would go out well before the polarity change, because it would take a while before the applied voltage finally reached zero after the burning voltage was undershot.
• the time intervals between the change in polarity can be longer than 0.2 sec but shorter than 5 sec. In this area, the time intervals between the polarity changes are significantly longer than the period of the usual network frequency. Then there are no problems with interference radiation or violations of EMC regulations.
• the time intervals are also shorter than the cooling time of the cooling electrode under operating temperature.
• the thermal time constant of the UV light low-pressure lamp specified for this purpose is a combination of the thermal time constants of the electrodes, the gaseous filler and the lamp housing and can vary from lamp to lamp so that an exact specification of a limit value is not possible. It is also acceptable to drop below the operating temperature at the cost of the lifespan of the UV light low-pressure lamp. It is then necessary to apply an initially increased voltage to compensate, but this may be below the ignition voltage. However, the further the voltage falls below the operating voltage, the more the current load on the electrode rises, since with each polarity reversal matter is torn out of the surface layer of the electrode in question, thereby shortening the life of the electrode.
• the emitter voltage or the emitter current can be monitored after changing the polarity and the polarity can be changed again if the electrical power deviates from a desired value.
• the threshold value is preferably set at 3% below the power value at the start of a polarity change.
• the monitoring intervals for the power measurement are expediently shorter than the thermal time constant of the UN low-pressure lamp.
• the transition time in which the polarity changes can be shorter than the recombination time of the gas discharge column of the UV light low-pressure lamp.
• the switch forms an annular arrangement of four semiconductor switches, which are supplied with direct voltage or direct current at two opposite nodes.
• a bridge branch includes the UV light down lamp. Two diagonally opposite semiconductor switches are opened and closed alternately with two other diagonally opposite semiconductor switches.
• At least one of the semiconductor switches which can be closed at the same time can be designed as a controllable current source.
• This configuration has the advantage that a DC voltage source that is exclusively voltage-controlled can be used as the supply source for the entire arrangement. Here you can set the lamp's operating voltage.
• the control or regulatable current sources present in the respectively active branch of the circuit are used.
• the ignition device comprises a series connection of an inductance and a capacitance, which is arranged between the electrodes of the UV light low-pressure lamp.
• this series circuit can be connected to an AC voltage or AC power source and can be separated from the AC voltage or AC power source for ignition.
• the supply voltage source it is not necessary for the supply voltage source to have to apply the ignition voltage. Rather, it can be in the range of the usual operating voltage.
• the ignition voltage is generated by the fact that the current flowing in the inductance of the series circuit can no longer flow in a closed circuit when the semiconductor switches are opened and therefore builds up a high voltage, which ultimately leads to ignition because of the parallel connection to the discharge path of the UV light low-pressure lamp leads.
• the system then switches to stationary operation, with the diagonally opposite semiconductor switches of the ring circuit being closed alternately or opened and thereby establish the connection between the UV light low-pressure lamp and the voltage or current source.
• the series connection of an inductance and a capacitance can also be arranged in series with the heating coils of the electrodes of the UV light depressurization radiators, the alternating current applied before the ignition then simultaneously serving to preheat the heating coils.
• Such heating coils are particularly necessary in the case of amalgam-doped UV light low-pressure lamps, so that ignition can take place at all.
• the further development makes it possible to use the circuit with current limitation through the inductance and the capacitance in AC operation both for heating the filaments and at the same time the inductance for ignition of the UV light low-pressure lamp.
• An alternative embodiment of the ignition device can have a capacitance which is arranged between the electrodes of the UV light low-pressure lamp. Before the ignition, a DC voltage increasing to the value of the ignition voltage can be applied to this. After the ignition and decay of the voltage to the operating voltage, a smoothing capacitance is switched on via a semiconductor switch.
• the smoothing capacitance then serves to dampen a pulsating component of the DC voltage when the DC voltage is obtained by rectifying the low-frequency AC voltage of the supply network.
• the smoothing capacity which is larger than the ignition capacity due to its rating for the low frequency of the capacitance value, because of the switch-off option, its dielectric strength can be chosen to be lower than the ignition capacity, which is always parallel to the UN light low-pressure lamp and must be dimensioned for the ignition voltage.
• the ignition device can additionally comprise a series connection of capacitors, which in turn are arranged in parallel with the UV light low-pressure lamps.
• the capacitive voltage divider can be designed with the same or different capacitances.
• the ignition voltage which can be applied to the series connection of UV light low-pressure lamps and parallel capacities, reaches at least a value which multiplies the ignition voltage of the most ignitable UV light low-pressure lamp by the number of UV connected in series -Light low-pressure lamps corresponds.
• UV low-pressure lamp Once a UV low-pressure lamp has been ignited, its voltage drops to the lower operating voltage, so that the applied voltage is then more distributed to the remaining, not yet ignited UV low-pressure lamp.
• UV light low-pressure lamps then ignite almost simultaneously, because with each additional UV light low-pressure lamp that is fired, the voltage at the remaining UV light low-pressure lamps increases, thus forcing it Fast ignition even of unwanted UN light depressurizers that require a higher ignition voltage than UV light low pressure lamps that are easy to ignite.
• the maximum ignition voltage can be limited to a value which is only moderately greater than the required ignition voltage of a single UV light low-pressure lamp. Due to the unequal divider ratio, the ignition voltage across the series circuit is initially only effective with a dominant portion for a first UV light - low-pressure lamp that ignites thereon.
• the pending ignition voltage minus the operating voltage of the ignited lamp is divided into the division ratio of the remaining capacitive voltage divider between the remaining UV light low-pressure lamps, one of which again receives a dominating portion of the ignition voltage and ignites thereon. This process continues analogously until all UV light low-pressure lamps are ignited.
• the supply voltage of the ballast can be variable and can be adapted to the sum of the individual voltages of the UV light low pressure lamps in the case of a series connection of several UV light low pressure lamps.
• FIG. 2 shows an alternative embodiment according to FIG. 1, in which two switches are replaced by controllable current sources
• FIG. 3 shows a circuit corresponding to FIG. 2, but additionally with an ignition device
• Fig. 4 shows another alternative for an ignitor
• Fig. 5 shows an ignitor for a series connection of UV light low-pressure lamps.
• the ballast shown in the drawings in modifications serves to supply a UV light low-pressure radiator 10 with electrical energy from a voltage source 16.
• the voltage source 16 in FIGS. 1 and 2 is a DC voltage source that applies DC voltage to the electrodes 12 and 14 of the UV light low-pressure lamp 10.
• semiconductor switches 18, 20, 22 and 24 are provided.
• the semiconductor switches 18, 20, 22 and 24 form a ring, to whose one node between the semiconductor switches 18 and 20 or 22 and 24 the DC voltage source 16 is connected and to the other node between the semiconductor switches 18 and 22 or 20 and 24 , ie diagonally to the ring, the UV light low-pressure lamp 10 with its electrodes 12 and 14 is connected.
• the semiconductor switches are controlled in such a way that one pair of semiconductor switches 18 and 24 is always closed, while the other pair of semiconductor switches 20 and 22 is open and vice versa.
• the time intervals in which one pair of semiconductor switches is opened and the other pair of semiconductor switches is closed is dimensioned according to the thermal inertia of the UV light low-pressure lamp 10, which can be between 0.2 and 5 seconds. In practice, this time interval is approximately 0.5 seconds.
• a constant DC voltage or a constant DC current is present at the electrodes 12 and 14, the polarity of which is regularly changed in the interval between the time intervals.
• FIG. 1 clarifies the stationary operating case in which a gas discharge column is already present in the UV light low-pressure lamp.
• the voltage of the voltage source 16 must correspond to the operating voltage of the UV light low-pressure lamp 10 in a very closely tolerated manner without further current limiting measures.
• FIG. 2 shows a representation similar to FIG. 1, but in which instead of the semiconductor switches 22 and 24, adjustable or controllable current sources 26 and 28 are used. These take on the function of the semiconductor switches 22 and 24 from FIG. 1 as well as a current limitation. This eliminates a tightly tolerated design of the DC voltage source 16. Rather, the DC voltage source 16 can be designed for the maximum operating voltage, since the current then flows through the current sources 26 and 28 in the event of changes in the operating parameters, signs of aging or other tolerances of the UV low-pressure lamp 10 is limited to the permissible value.
• high-performance UV light low-pressure lamps also require the electrodes to be preheated so that the ignition is made easier or even possible in the first place.
• the illustration according to FIG. 3 shows a solution in which both heating of the electrodes and ignition is possible. This is therefore a practical version.
• the electrodes are designed as heating coils 30 and 32.
• a heating circuit leads from the nodes between the semiconductor switch 18 and the controllable current source 26 and the semiconductor switch 20 and the controllable current source 28 via the series connection of an inductor 34 and a capacitor 36.
• the UV light low-pressure lamp 10 is initially included AC operated. This can be done in that the voltage source 16 generates alternating voltage itself, or also in that the voltage source 16 is operated as a direct voltage source and the alternating voltage takes place by alternately switching the switches 18 and 20 and up and down in the current sources 26 and 28. A sinusoidal low to medium frequency AC voltage is assumed here.
• This alternating voltage allows a current to flow through the heating coils 30 and 32, which current is limited by the series circuit comprising the inductance 34 and the capacitance 36 that serves as a series resistor for the alternating voltage. Since the inductance 34 and the capacitance 36 alternately store energy in this preheating mode, the series connection can also be used for ignition.
• the switches 18 and 20 are opened and the controllable current sources 26 and 28 are blocked, whereupon the energy stored in the inductor 34 closes leads to a voltage rise in the heating coils 30 and 32, which now act as electrodes, and thereby causes the ignition of the UV light low-pressure lamp 10 after the ignition voltage has been reached.
• a gas discharge column then builds up in the interior of the UV light low-pressure lamp 10.
• the system is switched to stationary operation, the switches 18 and the controllable current source 28 being opened and closed alternately with the switch 20 and the controllable current source 26. Since the UV light low-pressure lamp 10 is then operated with direct current, the series connection of the inductance 34 and the capacitance 36 does not form a shunt.
• FIG. 4 shows a further alternative for an ignition device which comprises two capacitances 38 and 40 arranged parallel to the UV light low-pressure radiator 10.
• the capacitance 38 forms a main smoothing capacitance and the capacitance 40 forms an ignition capacitance.
• the main smoothing capacitance 38 can be switched on and off in parallel via a semiconductor switch 42. The ignition takes place in such a way that the DC voltage source 16 first causes the voltage at the ignition capacitance 40 to rise to the ignition voltage level. After ignition, the main smoothing capacitance 38 is connected in parallel via the semiconductor switch 42.
• the main smoothing capacitance 38 only has to be designed for the operating voltage of the UV light low-pressure lamp 10 in terms of its dielectric strength.
• FIG. 5 shows an igniter for a series connection of UV light low-pressure lamps. The design is based on the circuit according to FIG. 4, but several UV light - left
• the igniter comprises a series connection of capacitors 44, 44 'and 44' ', which in turn are each arranged in parallel to the UV light low-pressure lamps 10, 10' and 10 ''. This forms a voltage divider which applies the ignition voltage in the divider ratio of the voltage divider to the associated UV light low-pressure lamps 10, 10 'and 10' '.
• voltage sources 46, 46 ', 46' 'and 46' '' are provided, which can heat the electrode filaments 30, 30 ', 30' 'and 32, 32' and 32 '' individually or in pairs. Since heating is no longer necessary during the burning phase, the voltage sources 46, 46 ', 46' 'and 46' '' can be switched by switches 48, 48 ', 48' 'and 48' '' after the relevant UV light has been ignited. Low pressure radiator 10, 10 'and 10' 'are switched off.

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• Circuit Arrangements For Discharge Lamps (AREA)
• Physical Water Treatments (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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• Encapsulation Of And Coatings For Semiconductor Or Solid State Devices (AREA)

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• 2000
  • 2000-04-06 DE DE10016982A patent/DE10016982A1/de not_active Withdrawn
• 2001
  • 2001-02-09 DK DK01911440T patent/DK1181844T3/da active
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  • 2001-02-09 WO PCT/DE2001/000519 patent/WO2001078465A1/fr active IP Right Grant
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• 2002
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