JPH06215681A - Electric current transformer safety switch for fluorescent lamp - Google Patents

Abstract

PURPOSE:To short-circuit automatically the secondary coil of an electric current transformer while detecting the load opening condition of the electric current transformer, and prevent an electric shock or overheat of the electric current transformer by arranging a voltage detecting means and switching means. CONSTITUTION:Relays K1 and K2 as a voltage detecting means and always opening contact points S1 and S2 as a switching means, are provided. When an electrode 5 of a fluorescent lamp 4 is disconnected, the secondary current of an electric current transformer 2 is flowed all to a capacitor C1, and the terminal voltage becomes high, and the relay K1 is excited, and the contact point S is closed. Thereby, the secondary coil 3 of the transformer 2 is short- circuited through the parallel circuit of the capacitor C1, a capacitor C2 and an electrode 6. Next, when the lamp 4 is removed to be replaced, the relay K is also excited, and the contact point S2 is closed, and the coil 3 of the transformer 2 is short-circuited through the capacitors C1 and C2, so that high voltage is not generated between socket terminals of the lamp 4. Thereby, the accident caused by high voltage or overheat can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency constant current power supply system for supplying electric power from a high frequency constant current power supply to a fluorescent lamp by using a current transformer, and a secondary winding of the current transformer is opened. The present invention relates to a current transformer safety device for a fluorescent lamp for preventing such a situation.

[0002]

2. Description of the Related Art The present applicant has developed a connectionless discharge tube luminaire in which a current transformer is used to supply power to a discharge tube from a high frequency constant current power source, and has already been registered as a utility model ( See Japanese Utility Model Publication No. 64-5360). An outline thereof will be described with reference to FIG. 2. A single power supply line 12 connected to a high frequency constant current power supply 11 is allowed to pass a current transformer 13 and its secondary winding 14 is directly connected to both terminals of a discharge tube 15. Since the current does not flow in the secondary winding 14 before the discharge tube 15 starts discharging, the iron core of the current transformer 13 is saturated and the discharge starting voltage of the discharge tube 15 is increased in the secondary winding 14. A higher voltage appears, and after the discharge tube 15 starts discharging due to this voltage, a constant current according to the number of turns of the secondary winding 14 flows.

However, the discharge tube 15 may be broken or the discharge tube 1
When 5 is removed, a voltage higher than the discharge voltage of the discharge tube 15 appears in the secondary winding 14 of the current transformer 13, so if the secondary winding 14 is mistakenly touched when replacing the discharge tube, an electric shock may occur. In addition, there is a risk that the magnetic flux increases and the iron loss remarkably increases, and it is dangerous if the transformer is overheated and left as it is.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to detect when a load of a current transformer is in an open state and automatically short-circuit the secondary winding of the current transformer to prevent electric shock or current transformer. It is to provide a safety device for a current transformer for preventing overheating.

[0005]

In order to solve the above-mentioned problems, a current transformer safety device for a fluorescent lamp according to the present invention has both terminals of a secondary winding of a current transformer in which a high frequency constant current is applied to the primary winding. A fluorescent lamp is connected to one terminal of each of the two electrodes, a capacitor and a switching means are connected in parallel between the other terminals of the both electrodes, and a capacitor and a voltage detecting means are connected between the two terminals of each of the electrodes. Are connected in parallel, and the switching means is closed by the output of the voltage detecting means. The exciting coil of the relay and its normally open contact are used as the voltage detecting means and the switching means.

[0006]

When the current is flowing through the two electrodes of the fluorescent lamp, the current flowing through the capacitor connected in parallel to each electrode is small and the terminal voltage is low, but if either of the electrodes is cut off, the output of the secondary winding will be output. Since all the current flows through the capacitors connected in parallel to the disconnected electrodes, the terminal voltage increases,
This voltage is detected by the voltage detecting means, the switching means is closed, and both terminals of the secondary winding of the current transformer are short-circuited through two capacitors (and unbroken electrodes) connected in parallel to both electrodes. Similarly, when the fluorescent lamp is removed, the switching means is closed and the terminals of the secondary winding are short-circuited.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIG. A high-frequency constant current of 65 kHz and 10 A flows through the power supply line 1, and the power supply line 1 penetrates (that is, is wound one turn) as a primary winding of the current transformer 2. Also,
The secondary winding 3 is wound around the current transformer 2 for 18 turns, and both terminals thereof are connected to one terminal of each of the two electrodes 5 and 6 of the fluorescent lamp 4. A small-capacity lighting capacitor C for generating a discharge start voltage is connected between the other terminals of the electrodes 5 and 6, respectively. The fluorescent lamp 4 has a commercial rating of 100V and 110W.

A relay R ₁ is connected in parallel to the electrode 5 via a capacitor C ₁ and a rectifying circuit, and an electrode 6
A relay R ₂ is connected in parallel with the capacitor C ₂ and a rectifier circuit. The contacts S ₁ and S ₂ which are closed by the excitation of the relays R ₁ and R ₂ , respectively, are connected in parallel with the lighting capacitor C.

The values of the capacitors C ₁ and C ₂ are set to 0.1 μm.
Assuming F, the impedance at 65 kHz is (1 / 2πfC≈) 24Ω, and the rating is 110W.
Since the resistance values of the electrodes 5 and 6 of the fluorescent lamp 4 are 2 to 4Ω, the secondary current of the current transformer 2 (10 A / 18 turns = ) 0.56A almost flows to the two electrodes 5 and 6, the terminal voltage of the capacitors C ₁ and C ₂ is low, and the relay R ₁
Or R ₂ is never excited.

Now, assuming that the electrode 5 of the fluorescent lamp 4 is broken, the secondary current of the current transformer 2 is entirely in the capacitor C.
It flows to ₁ and the terminal voltage is (24Ω × 0.56A =) 13.
Since the voltage is 4 V, the relay R ₁ is excited and the contact S ₁ is closed. As a result, the secondary winding 3 of the current transformer 2 is short-circuited through the capacitor C ₁ and the parallel circuit of the capacitor C ₂ and the electrode 6. Then, when the fluorescent lamp 4 is removed for replacement, the relay R ₂ is also excited and the contact S ₂ is closed, and the secondary winding 3 of the current transformer 2 is connected to the capacitor C ₁
Therefore, a high voltage is not generated between the terminals of the socket of the fluorescent lamp 4 because of short-circuiting through C ₂ and C ₂ . When the broken fluorescent lamp 4 is replaced with a new one, the secondary current of the current transformer 2 flows through its electrodes 5 and 6, the terminal voltage of the capacitors C ₁ and C ₂ drops, and the excitation of the relays R ₁ and R ₂ disappears. The contacts S ₁ and S ₂ are opened and the capacitor C
A discharge start voltage is generated between both terminals of the fluorescent lamp 4 and the fluorescent lamp 4 is turned on.

[0011] Incidentally, Te is at the above embodiment uses two relays R ₁ and R ₂ which are excited respectively by the terminal voltage of the capacitor C ₁ and C _2, a relay with two exciting coils Alternatively, the normally open contact may be closed by exciting one of the exciting coils. Also, instead of using a relay, a condenser C
It is also possible to use voltage detection means (by an electric circuit) for detecting the terminal voltages of ₁ and C ₂ and switching means closed by its output. The frequency and current value of the high frequency constant current flowing in the power supply line, the shape of the current transformer,
The size, the winding ratio, the values of the capacitors C, C ₁ and C ₂ , etc. can be appropriately changed in design in consideration of the rating of the fluorescent lamp 4 and other conditions.

[0012]

As described above, the current transformer safety device for a fluorescent lamp according to the present invention is a fluorescent lamp in a high frequency constant current power supply system for supplying power to a fluorescent lamp using a current transformer from a high frequency constant current power source. The secondary winding of the current transformer can be automatically short-circuited when the lamp burns out or is removed for replacement, preventing accidents due to high voltage or overheating. The indicator is turned on to return to normal operation, and there is an effect that the operation is reliable and there is no fear of failure, and maintenance is extremely easy.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a schematic view of a conventional device.

[Explanation of symbols]

1 Power supply line 2 Current transformer 3 Secondary winding 4 Fluorescent lamp 5 and 6 electrode C Lighting capacitor
C ₁ , C ₂ condensers R ₁ , R ₂ relays S ₁ , S ₂ contacts 11 constant current power supply 12 power supply line 13 current transformer 14 secondary winding 15 discharge tube

Claims (2)

[Claims] 1. A terminal of a secondary winding of a current transformer in which a high-frequency constant current is applied to the primary winding is connected to one terminal of each of two electrodes of a fluorescent lamp, and the other terminal of each of the two electrodes is connected. A fluorescent lamp characterized in that a capacitor and a switching means are connected in parallel with each other, a capacitor and a voltage detecting means are connected in parallel between each two terminals of the both electrodes, and the switching means is closed by the output of the voltage detecting means. Current transformer cutout. 2. The current transformer safety device for a fluorescent lamp according to claim 1, wherein the voltage detecting means is an exciting coil of the relay, and the switching means is a normally open contact of the relay.