DE1049003B - Operating equipment for electric discharge lamps, in particular for use in railway vehicles - Google Patents

Description

The invention relates to electrical lighting systems with discharge lamps, in particular Fluorescent lamps such as those used in railway vehicles. As power sources for such Systems have established themselves with inverters fed by the usual vehicle battery. as The installation of turbo inverters has proven to be particularly suitable for sieving the discharged A filter throttle is connected downstream of the current. The resulting supply voltage then shows a sinusoidal curve.

Fluorescent lamps with preheatable electrodes are known to be strong in these systems Scope operated by means of inductive ballasts. To compensate for the inductive "reactive current the fluorescent lamps, as is common practice, capacitors individually or together in parallel assigned to the network.

It has now been shown that the filter choke connected downstream of the inverter in certain Cases of operation can come into resonance with the compensation capacitors, namely then, when the fluorescent lamps are partially or completely switched off, while the compensation capacitors still hanging on the network. This case also occurs when the fluorescent lamps have just been switched on but have not yet ignited, e.g. B. when the associated glow starter starts up. This process results in a strong increase in the supply voltage, so that the fluorescent lamps, the electrodes of which actually have to be heated up before the ignition voltage is applied, as a result of the high peak values of the resonance overvoltage ignite even with cold electrodes. The lifespan like that operated lamps is greatly reduced by such cold ignitions. Also for security reasons and Such an increase in voltage is undesirable because of the stress on the insulation.

To remedy this inconvenience, it has already been proposed to connect an iron choke coil premagnetized from a special direct current source in parallel to the supply voltage, the direct current for the premagnetization being made dependent on the operating voltage applied to the discharge lamps. This circuit is quite intricate as it requires a complicated multi-turn inductor and a multi-wave rectifier. In contrast, according to the invention, an iron choke coil with no direct current bias or other external influence is used with such characteristics that, with the nominal supply voltage, only a small current is consumed
Discharge lamps, especially for
Use in railway vehicles

Applicant:

Patent trust company
for electric light bulbs mb H.,
Munich 2, Windenmacherstr. 6th

Dipl.-Ing. Hermann Ramert and Frithjof Blum, Munich, have been named as inventors

this value increases more than proportionally. This way, with the simplest circuit and one only an iron choke coil carrying a single winding ensures automatic overvoltage avoidance, regardless of how many lamps are connected to the supply voltage. Such Ei sendras seispulen, which have a pronounced as a result of entering the saturation range of the iron core Have kinks in their characteristics are known per se, and circuits are also used such choke coils have become known, in which desired resonance overvoltages through their effects are limited. However, the known cases use one supplied by the inverter unscreened voltage of rectangular waveform, and it was used for each lamp or its ballast special choke coils of this type provided, the effect of which is still through upstream Resistances experienced a damping.

The present problem arises, however, from a circuit which, in order to achieve sinusoidal Supply voltage provides a filter reactor behind the inverter and is independent of the on the changing number of lamps switched on with a single iron choke coil Overvoltages should be avoided at all. It has been found convenient to use the iron choke sink to give such a characteristic that the current flowing through it with an increase in the applied Voltage increases by 10% above nominal voltage by about 500%. The iron choke coil can be turned into adjust their characteristics so that the current flowing through them with increasing supply voltage so increases that the capacitive reactive current through a

809 73O / 202

Claims (6)

corresponding inductive reactive current is compensated. An embodiment of the operating equipment according to the invention is shown in the drawing. By means of a turbo inverter 1, the direct voltage of the collector 2 is converted into an alternating voltage, which is screened by the downstream filter throttle 3 so that it practically assumes a sinusoidal shape. The supply voltage to be taken from terminals 4, 5 is supplied on the one hand to the lighting systems A, B ... with fluorescent lamps 8, which are available in any number of times, and on the other hand to one or more compensation capacitors 6. Each fluorescent lamp 8 includes the current limiting inductor 10 and the ignition switch 9, z. B. a glow starter. Such an arrangement contains, for example, a total of 21 lighting systems A, B. The mains voltage then present at terminals 4, 5 should be 220 V. If some of the lamps are now switched off, a resonance overvoltage occurs as a result of the resonance conditions between the capacitor 6 and the filter choke 3. When all lamps are switched off, this can assume values of up to 500 V or even more. Even if, instead of a single compensation capacitor 6, several are used, each of which is assigned to a lighting system A, B..., Such resonance overvoltages can occur. This happens in particular when several lighting systems A, B ... are switched on simultaneously via a main switch 11 and initially only the associated glow starter 9 is glowing, or the fluorescent lamp has not yet ignited for other reasons, i.e. no significant current through the choke coil 10 flows. These harmful overvoltages not only cause the fluorescent lamps to ignite when the electrodes are cold, they also put a strain on the turbo inverter and the DC side, endangering the environment and the insulation. To avoid this, an iron choke coil 7 is connected in parallel to the mains terminals 4, 5 according to the invention. It is expediently dimensioned in such a way that it is able to supply an inductive reactive current, which changes greatly depending on the applied voltage and represents a replacement for the missing inductive reactive currents of the switched-off lighting systems A, B ... By a suitable choice of the iron used for the choke coil it is easy to choose the characteristics of the choke coil so that at normal mains voltage, in the present example 220 V, only a very small current through the choke coil 7 of e.g. B. about 0.5 Amp. Flows. But as soon as the voltage in terminals 4, 5 begins to rise as a result of the circumstances described, the choke coil 7 takes on a rapidly increasing current, which increases much more than the applied voltage, because the saturation range of the iron core is now reached. For example, it is possible to dimension the choke coil 7 so that when the voltage rises by 10%, that is to say to 242 V, the current already rises by 500%, that is to say to 2.5 amps. As a result of this increase in current, a further increase in the network voltage is prevented or slowed down. Tension rises by 10% or a similar amount are still to be regarded as harmless. In addition, the capacitive reactive current of the capacitor 6 is now compensated again, so that the converter is not overloaded. The choke coil 7 also ensures a more favorable curve shape for the supply voltage. The use of this choke coil offers the great advantage that its voltage-regulating effect occurs immediately and automatically adapts to the respective requirements, regardless of whether only some or all of the lighting systems A, B ... are switched off. Patent claims: 1. Operating equipment for electric discharge lamps, in particular for use in Railway vehicles whose AC supply voltage comes from a direct current source via a The inverter is supplied with a downstream filter choke and with several fluorescent lamps are connected in parallel via an inductive current limiter each and the inductive reactive current compensated via one or more capacitors connected to the supply alternating voltage and in which a choke coil limiting the line voltage increase parallel to AC supply voltage is switched, characterized in that one without DC bias and other iron choke coil with such characteristics which remain outside the influence is used, which draws only a small current at the nominal supply voltage, that when the voltage increases slightly as a result of entering the saturation range of the iron core increases more than proportionally above this value. 2. Betriebseinriclitung for electric discharge lamps according to claim 1, characterized in that that the iron choke coil has such a characteristic that the one flowing through it Current increases by around 500% when the applied voltage rises by 10% above the mains voltage. 3. Operating device for electric discharge lamps according to claim 1 and 2, characterized characterized in that the iron choke coil has such a characteristic that the flowing through it When the supply voltage rises, the current increases so that the capacitive reactive current is compensated by a corresponding inductive reactive current. Considered publications:
British Patent Nos. 583 925, 545 854. 1 sheet of drawings . © 809 730/202 1.59