FI63849C - MEDICAL DESCRIPTION OF ELECTRICAL SYSTEMS FOR ELECTRONIC ELECTRONICS - Google Patents

Description

1 63849

Electronic mains connection device for the discharge lamp with adjustable phase angle of the supply voltage. - Mednn-spänningens fasvinkelreglerare regullerbar elektronisk nätanslutningsanordning för en urladdningslainpa.

5

The invention relates to an electronic mains connection device for a discharge lamp controlled by a phase angle regulator of a supply voltage, comprising a lamp circuit comprising a high-frequency generator, in front of which is connected a DC filter capacitor connected via a rectifier.

15 Such a mains connection device is known from the applicant's previous Finnish patent application No. 813297. If the lamp is disconnected from such a mains connection or the lamp circuit otherwise draws a small amount of electricity, the voltage of the DC filter capacitor rises to a dangerous value when using a phase angle regulator. This is because the resonant frequency of the filter choke 2 and the capacitor 3 (cf. Fig. 1) is practically higher than the mains frequency and the oscillation of this circuit with the voltage curve shape provided by the phase angle controller (example of the ice-25 shape curve in the filter capacitor unless this is sufficiently loaded. This results in the destruction of the capacitor 6 and / or the phase angle regulator due to overvoltage. 30

The object of the invention is to enable the electronic connection device of the discharge lamp to be adjusted with a phase angle regulator without the overvoltage hazard described above. This object is achieved on the basis of the features of the invention set out in the appended claims.

An embodiment of the invention will now be described in more detail with reference to the accompanying drawings, in which Fig. 2 63849 shows a circuit diagram of the switching principle according to the invention and Fig. 2 the above-described mains voltage after the phase angle controller 1 at a control value.

After the phase angle regulator 1 cutting the front edge of the supply voltage wave according to Fig. 2, a filter circuit formed by the choke 2 and the capacitor 3 is connected. The choke 10 2 may be as shown entirely in the second supply line of the mains electricity or it may be partially divided in both conductors. After the rectifier 5, a large electrolytic capacitor 6 acting as a filter capacitor is connected, which supplies power to the lamp circuit 15 7, 8. The lamp circuit 7 comprises a high-frequency generator, a more detailed circuit solution 20 come into question.

Essential to the invention is a switch connected in series with the capacitor 3, in this case triac 4, which disconnects the capacitor 3 from the circuit when the lamp 8 is removed or the lamp circuit 7, 8 otherwise loads the capacitor 6 so little that the resonant oscillation circuit formed by the choke 2 and the capacitor 3 in phase angle control mode raises the circuit voltage to a dangerously high level. In the case shown, the triac 4 is arranged 30 to be controlled by a current transformer 9, 10 sensing the current of the lamp 8, so that when the current of the lamp 8 falls below a certain value, the normally conducting triac 4 becomes non-conductive. It is clear that instead of the triac 4, any electrical switch 35 can be considered, such as a relay, thyristor + diode, transistor or the like semiconductor or other electrical switch. It is essential that the capacitor 3 becomes sufficiently disconnected from the circuit when the capacitor 6 is not sufficiently loaded by the stepping circuit.

3 63849 For this purpose, it is also possible to use an artificial load connected to the capacitor 3, e.g. a thermal resistor with a positive temperature coefficient connected in series with the capacitor 3, the resistance value of which increases sharply when the capacitor current exceeds a predetermined value.

The switch 4 can also be controlled so that it opens (e.g. the triac becomes non-conductive) under the control of the voltage of the capacitor 6 when, for one reason or another, the voltage of the capacitor 6 rises to an undesired value. This embodiment also protects the supply network against overvoltage.

The invention is, of course, not limited to the circuit diagram according to Fig. 15, but e.g. also applies to cases where there is a capacitance in parallel with the capacitor 3 which is not disconnected from the circuit when the capacitor 3 is disconnected.

Claims (4)

4,63849 An electronic mains connection device for a discharge lamp adjustable by a supply voltage phase angle regulator (1), comprising a lamp circuit (7) comprising a high-frequency generator, in front of which is connected a DC filter capacitor (6) connected via a rectifier (5) and a choke (2) ) to a filter circuit connected to an AC voltage source via a phase angle regulator (1), characterized in that a current limiting or switching member (4) is connected in series with the filter circuit capacitor (3), which limits or cuts off the capacitor (3) if the DC filter capacitor (6) the voltage tends to rise above the desired value or the generator load falls below a predetermined value. Mains connection device according to claim 1, characterized in that said current limiting or disconnecting member is an electronic switch (4) arranged to be controlled so as to open when the generator load falls below a predetermined value or the DC filter capacitor (6) voltage exceeds a predetermined value. value or when the current of the capacitor 25 (3) exceeds a certain value. Mains connection device according to Claim 2, characterized in that the electronic switch is a triac (4) which is controlled by means of a means (9, 10) for sensing the load on the generator. Mains connection device according to Claim 1, characterized in that a thermal resistor (PTC) with a positive temperature coefficient is connected in series with the capacitor (3) of the filtering circuit, the resistance value of which increases sharply when the current of the capacitor (3) exceeds a predetermined value. 63849