DE1013009B - Device for series operation of low-voltage fluorescent lamps with warm cathodes - Google Patents

Description

GERMAN

For series operation of low-voltage fluorescent lamps with warm cathodes on high DC voltage A relay or contactor is known via an ignition throttle or the like and a limiting resistor - hereinafter referred to as the main relay - to be used with normally closed contacts through which the cathodes the lamps are connected in series and preheated after being switched on to the mains voltage and which triggers the ignition voltage surge when opening and takes effect on the lamps. For controlling of the main relay, a bimetallic switch or other delayed auxiliary relay is used, which the Preheating time determined.

The invention relates to such a device or circuit and is characterized in that the auxiliary relay has two exciter windings which act in the same direction and are connected to partial voltages of the lamp circuit, each of which is assigned a timing element, in particular an RC Gl'itd , with one winding largely causes the auxiliary relay to hold, while the other significantly influences the response and, if necessary, is switched off by the main relay after the lamps have been ignited.

The device according to the invention is particularly suitable for series operation of low-voltage fluorescent lamps for systems in which more often rnjt temporary short-term power interruptions is to be expected, e.g. for electric trams. Interruptions can easily occur here while driving occur between contact wire and pantograph. As the life of warm cathode fluorescent lamps strongly depends on the number of ignition voltage surges that have occurred, care should be taken to ensure that that such short-term power interruptions do not cause the triggering voltage surge to respond Lead relay. The lamps can, provided the power interruptions are not too long Are permanent, reignite automatically when the mains voltage returns, since their ionization has a certain Time is maintained. In a further embodiment of the invention, therefore, the holding of the auxiliary relay influencing excitation winding means for achieving a dropout delay, e.g. B. a parallel capacitor, assigned. In this way, unnecessary ignition voltage surges in the event of brief power failures, after which the lamps can ignite again by themselves can be avoided.

The above problem has been recognized earlier. However, the chosen turned out to be Solvents, namely a parallel capacitor on the main relay, are disadvantageous. The main relay carries the heavily used contacts for the ignition process and therefore required for safe working relatively large currents. Do you want a waste disposal facility for serial operation

of low voltage fluorescent lamps

with warm cathodes

Applicant:

Siemens-Schuckertwerke

Corporation,

Berlin and Erlangen,

Erlangen, Werner-von-Siemens-Str. 50

Dipl.-Ing. Karl Fischer, Nuremberg,
has been named as the inventor

reach delay, the parallel capacitor must have considerable capacitance values if it has the to deliver high relay currents for a while. Even then, however, there is a precisely measured dropout delay not easily possible.

The invention avoids these disadvantages in that the dropout delay is also impressed on the auxiliary relay will. The auxiliary relay with its vanishingly small excitation currents requires accordingly also only a very small parallel capacitor for the required dropout delay. It can take effort and space requirements can be significantly reduced.

In the device according to the invention, the function of the ignition device can still according to a further Side can be advantageously expanded. During, after brief power interruptions, the lamps reignite automatically, the cathodes have to be heated up after longer interruptions be. The duration of this heating depends on how long the operating current is interrupted was. There is therefore a connection between the interruption times and the subsequent ones Reheat times. This connection can be made with the help of the timing element which is used for the response

4-5 of the auxiliary relay is assigned to the relevant winding, be replicated. This limits the failure of the lighting to what is absolutely necessary. This substantial operational advance requires thanks to the device according to the invention used auxiliary relays only a negligible effort. It is z. B. just an additional one Resistance needed.

All these switching functions of the auxiliary relay can be particularly advantageous through a polarized relay

709 590/278

(T relay) are met. Such relays have a long service life and work very precisely. aside from that they are characterized by small quiescent currents, so that the losses generated by them are practically negligible are. The timing capacitors can be kept particularly small with T-relays.

To explain the invention in more detail, two circuit examples of the new device are shown in the drawing shown.

In Fig. 1 to a direct current network PN high voltage more, for. B. three low-voltage fluorescent lamps 1 to 3 are operated with warm cathodes. Each of the lamps is _{bridged by a break contact J 1} to J _{3 of} a main relay 6 ″.

At the same time, however, another important function for the operation of the lamps, namely the avoidance of unnecessary ignition voltage surges triggered by the relays, is fulfilled in the event of brief, unwanted power interruptions, so that the lamps can re-ignite automatically in such cases due to their ionization which continues for a while. If the current supplied to the PN terminals is temporarily interrupted, the auxiliary

■ o relay R is still attracted for a time determined by the size of the capacitor 15. If the mains voltage returns during this period of time, so that the auxiliary relay R and the main relay S "are not yet actuated, the lamps can, without

The operating voltage of the relay 5 ″. Is at the same 15 that a new ignition voltage surge is triggered, direct current network PN, for example in a voltage, immediately re-ignite by itself there is also a special one and removed from 6. The control of the main relay 5 ¹ advantage is that the time delay required for preheating the lamps is carried out via the contact r through the auxiliary relay R, exactly and independently, which has two excitation windings 9 and 10, of 20 from the Time delay acts and can be set, for example, from the voltage drop of the lamps, which can cause unnecessary dropping and restarting of the lamps and the second from the voltage drop in the relay, i.e. unnecessary ignition voltage surges, in series with the ignition choke 7 in the lamp operating current - short-term temporary power interruptions circuit lying limiting resistor 8 fed prevented,
will. To achieve the required arousal 25

voltages of the relay windings of the auxiliary relay R are two optionally adjustable resistors 11 and 12. In series with the excitation winding 10 is another normally closed contact S _{i of} the main relay S. In addition, another normally closed contact J _{5 of} this relay is provided, which is parallel to a resistor 13 and serves to shorten the required lamp preheating time. The resistor 13 can also be part of the limiting resistor 8.

If the mains voltage is applied to the circuit described _{, the preheating of the lamps 1 to 3 begins immediately via J 1} , S ₂ , s _s , 7, 8. The winding 9 of the auxiliary relay R is excited via the resistor 11 from the voltage drop in the limiting resistor 8 and at the same time its winding 10 from the voltage drop of the lamps across J ₄ , 12. After the response delay determined by the capacitors 14 and 15, the contact r is closed, whereby the main relay 6 "receives voltage and responds. The contacts S ₁ to j _k open. By opening J. ,, s,

₂ and J ₃ arises, triggered by the

Ignition throttle 7, the ignition voltage surge on lamps 1 to 3, causing them to ignite. By opening the contact J ₄ , the excitation winding 10 of the auxiliary relay R is de-energized. The relay R does not drop out, however, but continues to be held by the field winding 9 without interruption. The voltage across the resistor 8 decreases after the lamps 1 to 3 have been ignited, since the resistance of the lamps increases as a result of the opened contacts J ₁ to J ₃ and thus the voltage across the lamps. The resistor 11 in the circuit of the excitation winding 9 is therefore dimensioned in the present example so that the voltage generated at the resistor 8 is still sufficient with certainty to hold the relay. Finally, when the lamps are ignited, contact J ₅ opens. This gives the lamps their intended operating voltage. The voltage change occurring at the resistor 8 when the resistor 13 is switched on must also be taken into account with regard to the holding of the auxiliary relay R.

As mentioned above, the size of the capacitors 14 and 15 determines the preheating time of the lamps. The device or circuit according to the invention according to FIG. 1 can be modified in many ways. For example, the voltage for feeding the various relay windings can also be taken from other resistors in the lamp circuit. The contact J ₄ can also be provided in the circuit of the field winding 9 instead of in the circuit of the field winding 10. 2 shows an example of this. In this case, the resistor 12 and the auxiliary relay R must be dimensioned so that the voltage of the lamps after they have been ignited is sufficient to hold the auxiliary srelais R on the relay winding 10 alone. The circuit according to FIG. 2 works similarly to that of FIG. 1, but with the essential difference that the preheating time of the lamps, especially in the case of longer power interruptions, which require actuation of the relays and thus a preheating process, automatically corresponds to the duration of the respective power interruption is adjusted. In the event of a brief power interruption, the relay 10 is also held here with the aid of a capacitor 14 so that the contacts of the relays R and 6 ″ are not actuated. In the event of longer power interruptions, however, the relay contacts r and J ₁ to J _{5 are actuated} Voltage begins to discharge the capacitor 15. The discharge process is not influenced by switching over the contact 6 "4 if the resistance values from 9 to 16 are the same. When the mains voltage returns, the capacitor 15 begins to charge again. After the time delay caused by it, the relays R and J? actuated exactly as when switching the lamps on to the mains voltage. The result is that in the case of a relatively long power interruption, the lamps are preheated for a correspondingly long time, while in the case of relatively short interruptions, preheating takes place correspondingly briefly. The preheating time of the lamps is thus adapted to the respective duration of a power interruption.

Claims (6)

PATENT CLAIMS: 1. Device for series operation of low-voltage fluorescent lamps with warm cathodes at high DC voltage via an ignition throttle or the like and a limiting resistor below Use of a relay or contactor (main relay), through whose normally closed contacts the cathodes of the lamps are connected in series during preheating and through the opening of which the ignition voltage surge becomes effective at the cathodes, whereby an on-delay auxiliary relay is used to operate the main relay to achieve a preheating time and, on the other hand, means are provided for maintaining the burning circuit in the event of mains voltage failures ended within the deionization period of the lamps, characterized in that the auxiliary relay (R) has two exciter windings (9, 10) which act in the same direction and which are connected to partial voltages of the lamp circuit, each of which has a timing element, in particular one i? C element is assigned, whereby one winding (9) has a decisive effect on holding the auxiliary relay, while the other (10) has a decisive influence on the response and is preferably switched off by the main relay after the lamps have been ignited. 2. Device according to claim 1, characterized in that an excitation winding (10) of the Auxiliary relay from the voltage drop across the lamps, the other field winding (9) from the voltage drop of the limiting resistor is fed. 3. A device according to claim 1 or 2, characterized in that the exciter winding (9) relevant for the holding is assigned means for achieving a drop-out delay, e.g. a parallel capacitor, in the sense of avoiding unnecessary ignition voltage surges triggered by the auxiliary relay in the event of such brief power interruptions, after which the lamps can re-ignite by themselves as a result of their ionization. 4. Device according to claims 1 to 3, characterized in that the lamp preheating time determining time delay can be set independently of the time delay that triggers the relay prevents short-term power interruptions. 5. Device according to one of claims 1 to 4, characterized in that the preheating time of the lamps after longer power interruptions, which cause an ignition voltage surge and thus a Make actuation of the relay necessary, automatically for the duration of the respective power interruption is adapted. 6. Device according to one of claims 1 to 5, characterized in that as an auxiliary relay a polarized relay (T-relay) is used. Considered publications:
French patent specification No. 961 205. 1 sheet of drawings © 709 590/278 7 '.