JPS63294232A - Changeover circuit for emergency lighting fixture - Google Patents

Abstract

PURPOSE:To obtain a noncontact changeover circuit having high reliability by simple circuit constitution by connecting a current transformer in series between an AC power and a discharge lamp by a circuit changing over the AC power and a DC power and lighting the discharge lamp. CONSTITUTION:In a circuit connecting a discharge lamp 8 to an AC power and a DC power 11, supplying electric power from the DC power 11 through an inverter 5 when the AC power is service-interrupted and lighting the dis charge lamp 8, a current transformer 7 is connected in series between the AC power and the discharge lamp 8. Consequently, high-frequency currents are not bypassed by a glow starter 10 on lighting from the DC power 11, and the discharge lamp can be lit surely. The primary side impedance of the current transformer 7 is increased on the service interruption of the AC power, thus changing over the power supplies in a noncontact manner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a switching circuit for an emergency lighting device suitable for making a switching circuit between an AC power source and a DC power source contactless.

[Conventional technology]

Regarding the switching circuit between the AC power source and the DC power source for emergency lighting equipment, as described in Japanese Patent Laid-Open No. 143999/1989, a saturable reactor is provided in the regular circuit that connects the AC power source and the discharge lamp. When the AC power supply is energized, the control winding of the saturable reactor is biased to DC to make the magnetic flux generated in the opposite direction larger than the saturation magnetic flux, completely saturating the core, and reducing the inductance of the load winding to almost zero. There is a circuit that prevents the voltage drop from occurring. The above circuit has the advantage of being cheaper than a relay switching system and having less noise than a semiconductor switching system, but it does not seem to have been put into practical use, and the only switching circuits that have actually been put into practical use are: The circuit is as shown in FIG. In other words, when the AC power supply is energized, the power failure detection relay 2
5, the contacts 202 and 203 are set to the a side for regular lighting, and the contact 201 is set to the a side to charge the battery 11.

When the AC power supply is cut off, the contacts 201, 202 and 203 are all switched to the b side, the battery 11 is connected to the emergency lighting inverter 5, and the fluorescent lamp 8 is turned on in an emergency.

FIG. 3 shows a conventional non-contact emergency lighting equipment lighting circuit. In the above circuit, the reactance 18 has a high impedance for high frequencies (several tens of KHz). When the AC power is turned on, the triac 19 is made conductive by the bidirectional voltage element 20, so that the fluorescent lamp 8 is turned on by the choke transformer 6 and the glow starter 1o. Note that since the AC power source has a low frequency, the reactance 18 has a low impedance, and the glow starter 10 operates to light the fluorescent lamp 8 without being affected by the reactance 18. On the other hand, the emergency lighting inverter 5 operates when the transistor 24 is on, but when AC power is applied, the base current of the transistor 24 does not flow because the base potential is higher than the emitter potential, so the transistor 24 is on. do not. Therefore, the emergency lighting inverter 5 does not oscillate. When the AC power supply is cut off, the base potential of the transistor 24 becomes lower than the emitter potential, the transistor 24 is turned on, and the voltage of the battery 11 is supplied to the emergency lighting inverter 5, so that oscillation starts. Therefore, high frequency power is applied to the fluorescent lamp 8 and the fluorescent lamp 8 is turned on. At this time, the impedance of the reactance 18 and the choke transformer 6 becomes large with respect to high frequencies, so leakage current from high frequency current returning to the emergency lighting inverter via the glow starter 10 and high frequency current flowing into the AC power source are prevented. be done. The method described above is used to make the device contactless.

[Problem that the invention seeks to solve]

In the above-mentioned conventional technology, the power failure detection relay is expensive and mechanically driven, so it cannot be said that the relay is highly reliable.

In addition, when a reactor is connected in series to the glow starter and a switch element is provided on the AC power source side, making it contactless, there is a problem that the circuit becomes complicated.

SUMMARY OF THE INVENTION An object of the present invention is to obtain an emergency lighting equipment switching circuit that is constructed with a simple circuit, is inexpensive, and has high reliability.

[Means for solving problems]

The above object is achieved by providing a current transformer in series between the AC power source and the discharge lamp, and connecting the secondary side of the current transformer in series to the glow starter.

[Effect]

When lighting a discharge lamp with an AC power source, the @ source is supplied via a current transformer, and the secondary side of the ``-2 current transformer is connected in series to the close starter. As a result, when starting the discharge lamp, the impedance of the current lance becomes almost zero, and the lamp is lit by the close starter. During emergency lighting, a high frequency is applied to the discharge lamp and the glow starter circuit, so the impedance on the secondary side of the current transformer increases in proportion to the frequency, and the glow starter prevents the high frequency current from being bypassed. lights up.

In addition, as the primary impedance of the current transformer increases along with the above operation, it also serves as a switching function on the AC power supply side, so it is also necessary to make the emergency lighting equipment lighting circuit contactless on the AC power supply side at the same time. Can be done.

〔Example〕

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of an emergency lighting equipment switching circuit according to the present invention. This embodiment is a non-contact circuit in which a current transformer is provided in series between the AC power source of the emergency lighting equipment and the discharge lamp.

The primary impedance of the current transformer is considerably smaller than the impedance of the choke transformer 6.
It does not have a large effect on the regular lighting circuit, and both the primary and secondary sides have low impedance at low frequencies and high impedance at high frequencies, and the coils are run in the same direction on the primary and secondary sides. Because it is rolled up, 1
When the primary and secondary coils are connected in series and an alternating current is passed from the opposite terminal to the other unconnected terminal, the primary and secondary coils cancel out the magnetic flux. Together, they are designed to almost eliminate impedance.

Immediately after the alternating current is applied, current is applied from the current 1 herance 7 to the secondary side of the filament 1-1 current transformer 7 of the discharge lamp 8 and to the close starter 1o.

As a result of the above, the impedance of the current transformer 7 becomes almost zero, and the glow starter 1o operates to light the discharge lamp 8. Furthermore, the emergency lighting inverter 5 operates when the transistor 4 is on and stops oscillating when the transistor 4 is off, but when the AC power is on, the base current of the transistor 4 is bypassed by the diode 16, so the is turned off, and the emergency lighting inverter 5 does not oscillate. When the AC power supply is cut off, the transistor 4 is turned on, and power is supplied from the battery 11 to the emergency lighting inverter 5, which starts oscillating. As a result, high frequency power is applied to the discharge lamp 8.

It starts discharging and turns on. At this time, since the secondary impedance of the current transformer 7 increases, it is possible to prevent the high frequency current from being bypassed by the glow starter 1o. Furthermore, since the primary side impedance of the current 1 herance 7 becomes large with respect to the AC power supply circuit, almost no high-frequency current leaks.

〔Effect of the invention〕

As described above, the emergency lighting equipment switching circuit according to the present invention includes:
In an emergency lighting equipment switching circuit that lights up a discharge lamp by switching between an AC power source and a DC power source, by providing a current transformer in series between the AC power source and the discharge lamp,
A non-contact emergency lighting equipment switching circuit that is inexpensive and highly reliable can be obtained with a simple circuit configuration.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of the emergency lighting equipment switching circuit according to the present invention, Fig. 2 is a diagram showing a conventional emergency lighting equipment switching circuit, and Fig. 3 is a circuit diagram showing a conventional emergency lighting equipment switching circuit. FIG. 3 is a diagram illustrating a lighting equipment switching circuit. 7...Current transformer, 8...Discharge lamp, 11...DC power supply. (Fig. 2, Fig. 7; Current Tra'/S, 8; Taiyasho ryding)
/l: 4 circles; original $ 3 figure

Claims (1)

[Claims] 1. An emergency lighting equipment switching circuit for lighting a discharge lamp by switching between an AC power source and a DC power source, characterized in that a current transformer is provided in series between the AC power source and the discharge lamp. Instrument switching circuit.