CN2342508Y

CN2342508Y - Over-current protector for electronic ballast

Info

Publication number: CN2342508Y
Application number: CN 98216840
Authority: CN
Inventors: 王宝良
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-07-07
Filing date: 1998-07-07
Publication date: 1999-10-06
Anticipated expiration: 2008-07-07

Abstract

The utility model discloses an over-current protector for electronic ballasts, which can be assembled with an electronic ballast composed of resistor and capacitor elements to form a fluorescent lamp electronic ballast with the over-current protection function. The utility model is form by the method that two triodes and one double-metal sheet temperature control switch are arranged on a radiating plate. The device has simple structure and reliable over-current protection, and is capable of enhancing the service life of the fluorescent lamp electronic ballasts.

Description

The electric ballast overcurrent protective device

The utility model relates to electronic ballast for fluorescent lamp, is in the improvement of being done aspect the overcurrent protection to electronic ballast for fluorescent lamp.

Existing electronic ballast for fluorescent lamp, with the fluorescent tube cooperating, when the fluorescent tube parameter just often, can operate as normal.In case fluorescent tube is longer service time, parameter changes greatly, or because of reason such as voltage, ambient temperature is low, when causing fluorescent tube normally not start, ballast is excessive because of output current, just can cause permanent damage.This is to influence the electronic ballast for fluorescent lamp main cause in useful life at present.

The purpose of this utility model is to provide a kind of electric ballast overcurrent protective device at above-mentioned problems of the prior art.To improve the reliability and the durability of electronic ballast for fluorescent lamp.

The technical scheme that realizes above-mentioned purpose is: a kind of electric ballast overcurrent protective device, and the temperature detect switch (TDS) of being made up of bimetal leaf and contact two triodes and is same to be contained on the heating panel and to constitute; The bimetal leaf electrode of its temperature detect switch (TDS) connects the collector electrode of a triode, and contact electrode connects the base stage of another triode.

This apparatus structure is simple, has reliable overcurrent protection function, can improve the useful life of electronic ballast for fluorescent lamp greatly.

Fig. 1 is an electric ballast overcurrent protective device topology view;

Fig. 2 is the circuit theory diagrams with electronic ballast for fluorescent lamp of this device.

The utility model is described in further detail below in conjunction with drawings and Examples.

Provide as Fig. 1, this electric ballast overcurrent protective device is with two triode T ₁, T ₂Constitute with being contained on the heating panel with a temperature detect switch (TDS) K who forms by bimetal leaf and contact; The bimetal leaf electrode of its temperature detect switch (TDS) meets triode T ₁Collector electrode, contact electrode meets triode T ₂Base stage.

Accompanying drawing 2 has provided the circuit theory diagrams of the electronic ballast for fluorescent lamp with this device.When this ballast and fluorescent tube cooperating just often, civil power is through D ₁-D ₄The bridge rectifier and the C that form ₂, C ₃The filter circuit conversion of forming is into about 310 volts direct current, through R ₁, C ₁, D ₅, D ₆After the trigger circuit triggers of forming, by T ₁, T ₂, L ₁Form self-oscillation Deng the high-frequency generator of forming, through inductance coil L ₂Start fluorescent tube R after the current limliting _DLuminous, fluorescent tube is normal when luminous, because of tube interior gas breakdown conduction, is resistive load.At this moment, the load of ballast mainly is fluorescent tube R _DInternal resistance.With 40 watts of fluorescent lamps is example, fluorescent tube internal resistance and L ₂The series connection total impedance in back is about 1200 Europe, flows through triode T ₁, T ₂Electric current be about 0.18 ampere, belong to normal operating conditions, the heating panel temperature rise is lower, when 40 ℃ of ambient temperatures, generally is no more than 80 ℃, the temperature detect switch (TDS) that is contained on the heating panel is inoperative, equals illusory.Ask longlyer when fluorescent tube uses, the pipe intrinsic parameter changes greatly, or because of reason such as voltage, ambient temperature is low, fluorescent tube can not normally be started light, when having only the two ends filament bright, because of tube interior gas not breakdown and non-conductive.This moment, the load of ballast mainly was a capacitor C ₄, be capacitive load, with inductance coil L ₂Form a series resonant tank, make and flow through triode T ₁, T ₂Electric current increase to about 0.4 ampere by 0.18 ampere, form over-current phenomenon avoidance.Triode T ₁, T ₂Temperature rise accelerate, the temperature of heating panel raises.When heating panel temperature rise to 110 ℃, the temperature detect switch (TDS) K that is contained on the heating panel connects, and forces triode T ₂Quit work the ballast no-output.The heating panel temperature reduces, and during the temperature detect switch (TDS) automatic disconnection, ballast starts again.At this moment, ballast is in the frequent starting state, and can not damage.New fluorescent tube is changed, and ballast can recover operate as normal, lights fluorescent tube.

Claims

1, a kind of electric ballast overcurrent protective device mainly is made up of triode and temperature detect switch (TDS), it is characterized in that it is with two triode T ₁, T ₂Constitute with being contained on the heating panel with a temperature detect switch (TDS) K who forms by bimetal leaf and contact; The bimetal leaf electrode of its temperature detect switch (TDS) meets triode T ₁Collector electrode, contact electrode meets triode T ₂Base stage.