EP1968357A2 - Supply unit for metal vapour lamps - Google Patents

Abstract

The supply unit (1) has a monitoring device (18) for verifying whether the supplied mains voltage is in a specified voltage range before or during lighting. A lighting circuit (12) is attached to the monitoring device. The lighting circuit is released for the generation of lighting impulse when the voltage monitoring circuit detects that the mains voltage lies in the specified voltage range.

Description

The invention relates to an improved supply unit for metal halide lamps.

Metal halide lamps, in particular high-pressure discharge lamps, are frequently operated with a series reactor on the public supply network. Together with an ignition circuit for generating Hochspannungszündimpulsen for igniting the still cold lamp results in a robust and reliable way to operate such lamps. However, faults can occur which can lead to an increase of the current and thus to an undue excessive heating of the operating device in the form of the series reactor. In this case, must the device will be switched off. For this purpose, usually a thermal switch, for example in the form of a bimetallic switch is used, which is heated by the operating current of the metal halide lamp.

During generic supply units, for example, the EP 1 528 577 A1 can be seen, goes to protect the supply unit usable thermal switch eg from the DE 102 58 281 A1 out. The thermal switch is integrated in a connection module there. The thermal switch is very compact. Overall, this allows the design of space-saving supply units.

The thermal switch is triggered by various heat influences. On the one hand, it assumes the ambient temperature. On the other hand, it heats up according to the current flowing through it. It thus acts as a slow overcurrent protection and switches off for larger overcurrents. In the case of large overcurrents, however, the thermal switch can rapidly overheat, which can lead to the evaporation of contacts and the formation of an arc. This is to be excluded, because in such a case, the supply unit damages.

On this basis, it is an object of the invention to provide a supply unit with thermal switch that allows safe operation or safe shutdown of the supply unit despite any miniaturization.

This object is achieved with the supply unit according to claim 1:

The supply unit according to the invention is suitable for metal vapor high-pressure lamps and also sodium vapor lamps. It has, in addition to the usual components on a monitoring device that checks the supplied mains voltage at least before the ignition of the lamp or even during the ignition of the same, whether the mains voltage is within a specified voltage range. If this is not the case, the generation of ignition pulses is suppressed at the ignition circuit.

The still cold lamp is initially high impedance. By ignition pulses in the form of high voltage pulses, a gas discharge is initiated, so that the lamp heating current flow through the lamp comes to conditions. In a voltage set range, for example, going from 180 volts to 240 volts, thereby laying the currents flowing through the lamp in an allowable range. However, if there is a network fault, such as a zero-conductor fault, it can lead to overvoltages that reach up to 440 volts. The ignition of the discharge lamp leads in such a case to currents that can lead to rapid overheating. The thermo-breaker responds, although it can not always switch off the high currents occurring safely. If an arc occurs at the thermal switch, it may possibly last longer and destroy the supply unit.

By suppressing ignition pulses in the event of overvoltage, this fault condition is avoided. The monitoring device must monitor whether the mains voltage is in a range of, for example, 0 volts to 240 volts. In the preferred case, however, ignition pulses are not generated even if the mains voltage falls below a lower limit, which is greater than 0, for example, 180 volts. This avoids that the discharge lamp is ignited at a mains voltage, which is not sufficient for safe operation of the lamp and would soon lead to re-extinguishing the lamp. If the lamp namely again and again goes out, it runs practically in continuous ignition operation and thus with increased wear. This too is prevented by the supply unit according to the invention.

The supply unit according to the invention preferably has a throttle for limiting the lamp current. This throttle may have a tap for generating ignition pulses. The tap is then connected to the ignition circuit. Alternatively, a separate ignition transformer may be provided, which is connected in series with the throttle.

The monitoring device may be connected to a corresponding deactivation input of the ignition circuit in order to disable it when an impermissible mains voltage is detected. It is also possible to combine the monitoring device and the ignition device into a circuit block by internally passing a signal indicative of improper mains voltage from a circuit part constituting the monitoring device to a circuit part constituting the ignition circuit.

The above-mentioned thermal switch is preferably connected in series with the throttle. The mains voltage is preferably tapped at a point lying in front of the thermal switch from the point of view of the mains connection and fed to the monitoring device. Alternatively, however, the mains voltage can also, at least as long as the discharge lamp still is not ignited, are tapped above the discharge lamp.

As a thermal switch is preferably a bimetallic switch in question. Preference is given to bimetal with Abschalthysteresis. If it has switched off, it cools down and can switch on again after some time. However, the generation of ignition pulses as long as the unacceptable mains voltage condition persists, so that the discharge lamp is not ignited but remains high-impedance and no current can flow through the lamp or the throttle and the thermal switch.

It is possible to cancel the blocking as soon as the unacceptable mains voltage condition disappears. However, it is also possible to provide the monitoring circuit with a memory, for example a flip-flop or other memory means, which stores and maintains the blocking state. The reset can be done for example by restarting an intermittently switched off mains voltage. Alternatively, it may require external intervention, for example by resetting an EPROM.

In a simple embodiment, the mains voltage monitoring is carried out before and / or during the ignition of the lamp. In an improved embodiment, it is possible to continuously perform the voltage monitoring and to prevent the generation of ignition pulses in the presence of a fault condition, but to interrupt the current flow through the gas discharge lamp. This can be done, for example, by a parallel to the gas discharge lamp switch is closed at least for a short time. Thus the discharge lamp goes out. If the switch is opened again, The discharge lamp would have to be re-ignited, but the ignition pulse generation is prevented as a result of the present overvoltage condition. Thus, the supply unit switches off safely in this case.

Instead of one of the discharge lamp connected in parallel switch can be connected in series with the discharge lamp and a semiconductor switch, which is at least temporarily switched to high impedance, if an overvoltage condition is detected and the lamp is thus turn off.

Further details of advantageous embodiments will become apparent from the following description with the drawings and claims. The description is limited to essential aspects of the invention and other conditions. The drawing gives the expert additional information, which is why reference is expressly made to the drawings.

• Figur 1 eine erste Ausführungsform der erfindungsgemäßen Versorgungseinheit in schematisierter Darstellung,
• Figur 2 eine zweite Ausführungsform der erfindungsgemäßen Versorgungseinheit in schematisierter Darstellung,
• Figur 3 eine dritte Ausführungsform der erfindungsgemäßen Versorgungseinheit in schematisierter Darstellung,
• Figur 4 eine vierte Ausführungsform der erfindungsgemäßen Versorgungseinheit in schematisierter Darstellung,
• Figur 5 eine fünfte Ausführungsform der erfindungsgemäßen Versorgungseinheit in schematisierter Darstellung und
• Figur 6 eine sechste Ausführungsform der erfindungsgemäßen Versorgungseinheit in schematisierter Darstellung.

In the drawings, embodiments of the invention are illustrated. Show it;

• FIG. 1 a first embodiment of the supply unit according to the invention in a schematic representation,
• FIG. 2 A second embodiment of the supply unit according to the invention in a schematic representation,
• FIG. 3 a third embodiment of the supply unit according to the invention in a schematic representation,
• FIG. 4 A fourth embodiment of the supply unit according to the invention in a schematic representation,
• FIG. 5 a fifth embodiment of the supply unit according to the invention in a schematic representation and
• FIG. 6 a sixth embodiment of the supply unit according to the invention in a schematic representation.

In FIG. 1 a supply unit 1 is illustrated, which serves to supply a high-pressure metal vapor lamp with electric power. The supply unit 1 according to FIG. 1 is at the same time ballast and ignitor. It is designed as 3- or 4-pole and has two network connections 3, 4 on the network side. These are connected to the electrical supply network, for example, an AC power supply with rated voltage 230 volts. On the lamp side, the supply unit has two Lampenan connections 5, 6, are connected to the leading to the metal vapor high pressure lamp lines. The supply unit 1 has its own housing 7, which in all FIGS. 1 to 5 only symbolically indicated. In this housing, at least preferably, a compensation capacitor 8 is provided, which connects the network terminals 3, 4 with each other. In the embodiment according to FIG. 5 the Netzanchluss 4 is connected to the lamp terminal 6. On the other hand, a thermal switch 9 and a throttle 10 are arranged in series between the mains connection 3 and the lamp connection 5. The thermal switch 9 is normally closed. It opens when it reaches an opening temperature by exceeding a limiting current. The thermal switch 9 is preferably designed as a bimetallic switch with switching hysteresis. For example, it can be housed in a terminal, as can be seen from the DE 102 58 281 A1 is known.

The throttle 10 is used in the circuit after FIG. 1 the current limit of the lamp current. It also serves to generate ignition pulses. For this purpose, it has between its ends a tap 11, to which an ignition circuit 12 is connected. The ignition circuit 12 is in FIG. 1 exemplified in a simple variant. To her belong in this embodiment, two capacitors 13, 14, which in Series are switched. The capacitor 13 branches off in front of the throttle 10 and leads via the capacitor 14 to a reference line 15, which in turn is in communication with the mains connection 4 and the lamp terminal 6. From the tap 11, a voltage-dependent switch, for example in the form of a DIAC 16 or a SIDAC, leads to the junction of the capacitors 13, 14. If the voltage on the capacitor 13 exceeds a limit, the switch 16 becomes low-resistance and discharges the capacitor 13 through turns of the inductor 10 until its charge is used up and the switch becomes non-conductive again. This game repeats periodically to generate firing pulses.

The capacitors 13, 14, a switch 17 is connected in series, which is normally closed. It serves to deactivate the ignition device 12 by a monitoring device 18, which is in operative connection with the switch 17 in order to open it as needed.

The monitoring device 18 serves to monitor the operating voltage applied to the supply unit 1. For this purpose, it is connected via corresponding lines, on the one hand, to the network connection 3 and, on the other hand, to the network connection 4.

The supply unit 1 described so far operates as follows:

Was the supply unit 1 for a long time without power, the metal vapor high-pressure lamp 2 is cold and thus high impedance. If operating voltage is now applied to the mains connections 3, 4, the mains voltage is applied substantially unimpeded to the high-pressure metal-vapor high-pressure lamp 2. Now it will the ignition device 12 is active. If the voltage on the capacitor 13 exceeds the breakdown voltage of the DIAG or switch 16, the latter discharges the capacitor 13 abruptly, as a result of which a sudden change in current occurs at the terminal 11. As a result, multiple Hochspannungszündimpulse be generated by means of the throttle 10 in each power half-wave, which lead to a gas discharge in the metal halide lamp 2. Before and / or during this, the monitoring device 18 checks whether the mains voltage lies within a permissible range of, for example, 180 volts to 240 volts. If this is the case, the generation of ignition pulses is continued until the metal vapor high-pressure lamp 2 carries a current which becomes so high that the voltage at the terminal 11 for maintaining tilt oscillations in the tilting oscillation generator formed by the capacitor 13 and the DIAG 16 no longer sufficient. The metal halide lamp 2 is in Anheizbetrieb over, where it draws increased current.

The heating operation leads to the heating of the metal vapor high-pressure lamp 2 until it goes into normal combustion operation. It then draws rated current. Now occurs when a lamp error, which leads to an increase in current, the thermal switch 9 is heated beyond its threshold and switches off. It is dimensioned so that it can easily switch off the operating current of the metal vapor high-pressure lamp 2.

If an attempt is made to ignite the metal vapor high-pressure lamp 2 when the mains voltage is outside the permissible range, the monitoring device 18 prevents the generation of ignition pulses. If, for example, a voltage of 400 volts is applied to the mains connections 3, 4, the Monitoring device 18 this immediately and opens the switch 17. The ignition device 12 can not generate ignition pulses. Consequently, although the increased mains voltage of, for example, 400 volts applied to the metal vapor high-pressure lamp 2. However, this is cold and non-conductive. Without ignition pulses, it can not carry any current. It thus does not come to a state in which an excessive current would flow through the thermal switch 9, which is not switched off by the thermal switch 9.

At the circuit after FIG. 1 Many modifications are possible, which will be readily apparent to those skilled in the art. For example, the monitoring device 18 may also be connected to the line between the thermal switch 9 and the throttle 10 instead of the mains connection 3. When switching on there is the same voltage as at the power connector 3. So nothing essential changes in function.

Alternatively, the monitoring device 18 can be connected to the lamp connection 5. At the moment of switching on, the metal vapor high-pressure lamp 2 has a high resistance, so that a voltage corresponding directly to the mains voltage is likewise applied to the lamp terminal 5. However, the voltage monitoring must then be limited to the period before the generation of ignition pulses.

FIG. 2 illustrates a modified embodiment. As far as construction or functional equality with the above-described supply unit 1 is, with respect to the structure and function of the functional unit 1a after FIG. 2 referred to the above description based on the same reference numerals. In contrast to the above Supply unit 1 assumes the throttle 10 but not the function of generating ignition pulses. For a separate ignition transformer 19 is provided. This is connected to a control circuit 20 which contains both the ignition device 12 and the monitoring device 18. With regard to function and possible modifications, reference is made to the description of the supply unit 1.

FIG. 3 illustrates a further modification of the supply unit 1a as a supply unit 1b. In addition to monitoring the mains voltage, the monitoring device 18 here takes over the monitoring of the switching state of the thermal switch 9. For this purpose, the monitoring device 18 is connected to both ends of the thermal switch 9. If he opens, a voltage drops over him, which is registered by the monitoring device 18. It can now block the monitoring of ignition pulses when re-closing the thermal switch 9. This feature prevents a too-aged or otherwise damaged metal vapor high-pressure lamp 2, which draws too large operating currents and thus leads to the thermal shutdown of the thermal switch 9 is ignited again after switching off.

The peel-off state may be stored in a memory module 21, for example in the form of a flip-flop or the like. The reset of the memory module 21 can be done for example by switching off and on the operating voltage. But it is also possible to make the reset of a manual intervention, such as a lamp replacement or a remote control signal or other measures.

The embodiments described above monitor the mains voltage in particular before and during the ignition. The following with reference to FIG. 4 described embodiment also allows the monitoring of the operating voltage and the timely shutdown of the supply unit 1c, even if the operating voltage runs out with ignited warm metal vapor high-pressure lamp 2 from the admissibility band.

For this purpose, for example, starting from the supply unit 1b or also starting from the other supply units 1a or 1, a switch 22 is provided, for example in the form of a TRIAC, which is connected in parallel to the metal vapor high-pressure lamp 2. Its ignition electrode 23 is connected to the monitoring device 18. If this detects an overvoltage condition at the power supply terminals 3, 4, it prevents, as explained above, the generation of ignition pulses. If it detects the overvoltage condition during normal combustion operation of the metal vapor high-pressure lamp 2, it gives at least one preferably several ignition pulses to the switch 22 in order to short-circuit at least one but preferably several mains half-waves of the voltage across the metal vapor high-pressure lamp 2. This extinguished by, the thermal switch 9 is still not responsive to the short-term overcurrent. If the switch 22 no longer receives ignition pulses, it becomes high-impedance. The extinguished metal vapor high-pressure lamp 2 is not ignited again, because the monitoring device 18, the ignition device 12 now blocks.

Another embodiment of the invention is described by the supply unit 1d FIG. 5 educated. For the explanation thereof reference is made to the above description. The throttle 10 may, as exemplified in FIG. 1 shown, also take over ignition function. Just as well, as in the Figures 2 . 3 and 4 illustrates a separate Zündübertrager be provided. In addition, a monitoring of the opening of the thermal switch 9 accordingly. FIG. 3 or 4 respectively. But this function can also be dispensed with.

The supply unit 1d allows, as the supply unit 1c, the monitoring of the mains voltage during normal operation of the metal vapor high-pressure lamp 2. This is connected in series with a semiconductor switch 24, which is at least briefly opened by the monitoring device 18, if they an overvoltage condition in the supply network after detects the ignition of the metal vapor high-pressure lamp 2. At the same time, in turn, the generation of ignition pulses is suppressed. If the metal vapor high-pressure lamp 2 has not yet ignited, the opening of the semiconductor switch 24 can be omitted.

FIG. 6 illustrates in simplified form a supply unit 1e, in which the switches 16 and 17 are combined to form a switch 25 in the form of an externally controlled switch, for example a TRIACs. This is on the one hand gegn mass and on the other hand connected via a series circuit of a capacitor 13 'and a coil 26 to the terminal 11 of the throttle 10. The gate of the TRIAC is connected to the ignition device. To generate lamp ignition pulses, this ignition device gives ignition pulses to the gate. The emission of ignition pulses is inhibited if the monitoring device 18, as described above in connection with FIGS. 1 to 5 described, an impermissible state. The advantage of this circuit lies in the absence of the separate Switch 17. Otherwise, the above description of the embodiments according to Fig. 1 to 5 corresponding.

For a supply unit of a metal vapor high-pressure lamp is proposed to provide relief of the existing temperature-dependent switching circuit breaker monitoring device 18, which monitors the mains voltage. If the mains voltage assumes values at which the metal vapor high-pressure lamp 2 suffers (undervoltage) or carries currents which can no longer be reliably switched off by the temperature switch 9, the monitoring unit 18 prevents the generation of ignition pulses, ie it blocks the ignition device 12.

reference numeral

1

supply unit

2

Halide high-pressure lamp

3

mains connection

4

mains connection

5

lamp connection

6

lamp connection

7

casing

8th

compensation capacitor

9

thermal switch

10

throttle

11

connection

12

ignition device

13

capacitor

14

capacitor

15

reference line

16

switch

17

switch

18

monitoring device

19

ignition transformer

20

control circuit

21

memory module

22

switch

23

ignition electrode

24

Semiconductor switches

25

switch

26

Kitchen sink

Claims (10)

Supply unit (1) for metal halide lamps (2), in particular high-pressure discharge lamps, for igniting and for supplying power to the lamps (2) from a network,
with a monitoring device (18) which checks the supplied mains voltage at least before or during ignition for whether the mains voltage is within a specified voltage range,
with an ignition circuit (12) connected to or containing the monitoring device (18) and which is enabled for ignition pulse generation only when the voltage monitoring circuit (18) has determined that the mains voltage is within the specified voltage range. Supply unit according to claim 1, with a choke (10) for adjusting the lamp current to a desired value. Supply unit according to Claim 1, characterized in that it has a current path leading from a mains input (3, 4) to the lamp (2), in which the ignition circuit (10, 12, 19) is arranged. Supply unit according to claim 3, characterized in that in the current path a thermal switch (9) is arranged. Supply unit according to claim 4, characterized in that the thermal switch (9) is a bimetallic switch. Supply unit according to claim 4, characterized in that the monitoring device (18) monitors, in addition to its function of power monitor the thermal switch (9) and inhibits the generation of ignition pulses if it had at least once opened. Supply unit according to claim 6, characterized in that the blocking is maintained until the next reconnection of the operating voltage. Supply unit according to claim 6, characterized in that the blocking is maintained until the next reset of an EPROM of the ignition circuit (12). Supply unit according to claim 1, characterized in that the lamp (2) a short-circuit switch (22) is connected in parallel, which is at least temporarily closed when the monitoring circuit (18) determines during the ignition that the mains voltage leaves the predetermined range. Supply unit according to claim 1, characterized in that to the lamp (2) a semiconductor relay (24) is connected in series, which is at least briefly opened when the monitoring circuit during of the ignition determines that the mains voltage leaves the predetermined range.

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