Electric lamp and discharge devices: systems – Pulsating or a.c. supply – Transformer in the supply circuit
Patent
1989-03-09
1991-05-14
LaRoche, Eugene R.
Electric lamp and discharge devices: systems
Pulsating or a.c. supply
Transformer in the supply circuit
315284, 315291, 315244, H05B 4118
Patent
active
050159224
DESCRIPTION:
BRIEF SUMMARY
The invention relates to power supply circuit for a gas discharge lamp operated at an a-c power source according to the preamble of claim 1. Power supply circuits of this type are generally known.
Gas discharge lamps show a non-linearity between the discharging current (lamp current) and the lamp voltage. The lamp voltage is a magnitude characteristic of the lamp and independent of the lamp current in a broad range. However, it becomes apparent that in the case of lamps with small output the voltage decreases somewhat with increasing current intensity. This makes the use of current limiting measures necessary to protect the lamp against destruction. In the case of lamps with great output the lamp voltage slightly increases with increasing lamp current. Small changes in the supply voltage ensue consequently in great changes in current so that in this case current-limiting measures are also necessary for stabilization.
Such current-limiting measures implemented in so-called chokes consist in gas discharge lamps fed from the a-c power line mostly essentially of a current-limiting reactor, which is connected in series with the lamp and produces a drop in voltage which should amount to about one third to one half of the mains voltage. Since the lamp acts roughly as resistive load, this drop in voltage is phase shifted by about 90.degree. with respect to the lamp voltage.
If the mains current of a gas discharge lamp is to be adjustable, a variation of the supply voltage comes only consideration to a very small degree because in the case of an optimized lamp circuit it has only a very limited influence on the mains current. The requirement that the instantaneous supply voltage must be greater than the arc drop of the lamp to avoid an extinction of the lamp sets limits to controllability. Therefore, in practice, the control is effected in the choke itself. Continuous lamp current adjustments in the partial load range are implemented by means of phase-controllable circuits or with transductors, therefore the choke must be correspondingly designed right from the beginning. In the high-load range one resorts to parallel or series connections of current-limiting reactors which makes a control only in relatively coarse steps possible if the expenditure should not become too great. It is in particular. stated with respect to phase-controllable circuits that the same produce a broad harmonics spectrum which is undesired for the lamp.
The invention is based on the object to indicate a power supply circuit of the type indicated at the beginning with which the power input of a gas discharge lamp can be adjusted in a broad range whose limits are in a ratio of up to about 3:1 to each other.
The invention thus extends the known power supply circuit by three additional components, namely by a regulating transformer, a capacitor and an auxiliary reactor, it being possible to design the auxiliary reactor to a small output as compared with the current-limiting reactor, and the regulating transformer must also only be designed for a correspondingly small output in accordance with the auxiliary current circuit consisting of the auxiliary reactor and the capacitor. The regulating transformer may be of a commercially available construction which is adapted to the supply mains voltage.
The current flowing in the auxiliary current circuit, i.e. in the auxiliary branch, is dependent only on the voltage at the auxiliary current circuit, i.e. in the minimum position of the transformer tap on the lamp voltage and in the maximum Position on the voltage via the current-limiting reactor. Depending upon the fact whether the lamp voltage or the voltage via the current-limiting reactor is larger, the current flowing in the auxiliary branch will also be higher or smaller in the minimum or maximum position. If the current and voltage nominal values of the auxiliary reactor are achieved, the auxiliary branch is optimally dimensioned. Therefore one cannot select optional capacitance values; if they are too high, the auxiliary reactor is overloaded. I
REFERENCES:
patent: 4695771 (1987-09-01), Hallay
patent: 4929871 (1990-05-01), Gerfast
Dinh Son
LaRoche Eugene R.
Ultralight AG
LandOfFree
Power supply circuit for a gas discharge lamp does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Power supply circuit for a gas discharge lamp, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Power supply circuit for a gas discharge lamp will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1650887