CN2132320Y - Simple circuit quick cut-off single phase leakage switch - Google Patents

Abstract

The utility model discloses a simple circuit quick cut-off single phase leakage switch which controls the switching of the output voltage in a contactless mode via a three-end two-way thyristor, comprising a housing, a leakage and electric shock sampling circuit, a sampling circuit of over-current and overvoltage, a voltage reduction and rectifying circuit of capacitor, a triggering signal control circuit of thyristor, a thyristor switch, etc. The triggering signal control circuit of thyristor adopts one-way thyristors which have sensitive triggering characteristics, which makes the circuit simple and reliable and have the functions of leakage protection, electric shock protection, over-current protection and over-voltage protection, and the utility model can cut off or switch off quickly the power supply between the circuit of leakage and electric shock and electric appliances.

Description

Simple circuit quick cut-off single phase leakage switch

The utility model belongs to the protective device with electric line and electrical appliance, is specially adapted to electric leakage, the electric shocked guard of uniline and electrical appliance thereof.

Before the utility model; the single-phase leakage switch of domestic production; all adopt the mechanical tripping device; the break-make of closing control output voltage of closing by hard contact; from the leakage switch of external import also is like this; the leakage switch make-and-break time of hard contact is 0.1 second; can pass through 5 cycles of 50Hz alternating current, so the electric shock that action the time will make electric shock person stand 5 cycles, the hard contact that has can not disjunction because of sheet metal elastic force difference; can not break away from power supply immediately after causing electric shock person to get shocked; misery unbearably, casualty accident happens occasionally, thus people wish to have the protection responsiveness faster; safer, fail safe can better come out by single-phase leakage switch.

The purpose of this utility model is to overcome the weak point of above-mentioned leakage switch, a kind of single-phase leakage switch that does not have main contacts is provided, do not adopt the mechanical tripping device, change mechanical contact and be divided into the contactless disjunction of outage minor, to shorten to 0.02 second operate time, simplify circuit, further improve security personnel's performance of single-phase leakage switch.

The utility model is achieved in that the single-phase leakage switch of being made up of housing and circuit, circuit does not adopt the mechanical tripping device, but adopt three terminal bidirectional thyristor (being bidirectional triode thyristor), break-make with contactless mode control output voltage, entire circuit is installed in the housing, entire circuit is by electric leakage electric shock sample circuit, overcurrent overvoltage sample circuit, capacitor step-down rectifier circuit, several parts such as thyristor triggering signal control circuit and thyristor switch are formed, its electric leakage electric shock sample circuit is by zero sequence current mutual inductor TA1, capacitor C3, compositions such as variable resistor VR1, capacitor step-down rectifier circuit is by capacitor C 1, C2, resistance R 1 and rectifier diode VD1, compositions such as VD2, thyristor triggering signal control circuit is by unidirectional thyristor VS2, VS3, compositions such as diode VD3-VD6, thyristor switch is made up of three terminal bidirectional thyristor VS1, housing is provided with power supply turnover line wiring pile, be provided with " phase line " and " zero line " mark near the wiring pile, also be provided with reset switch on the housing, the test button switch, mode indicator and nameplate, connection between each part of whole leakage switch makes gets an electric shock and the shock current that leaks electricity during less than leakage switch operating current value when unmanned, three terminal bidirectional thyristor VS1 in the leakage switch is conducting, leakage switch normally powers to the load, when getting an electric shock or leakage current when meeting or exceeding leakage switch operating current value, three terminal bidirectional thyristor VS1 turn-offed in 0.02 second fast, stop to power to the load, the following position of leakage switch output connection stake is in safe electroless state, after fault is eliminated, press the reset button switch, can recover normal power supply.

The characteristics of bonded block or circuit further specify: one, the three terminal bidirectional thyristor of control circuit break-make must be connected on the phase line lead of leakage switch, its negative electrode directly or by the overcurrent sampling resistor links to each other with leakage switch phase line inlet wire wiring pile, its anode by the phase conductor in the leakage switch on the zero sequence current mutual inductor iron core around some circles, and then link to each other with phase line outlet wiring pile.Two, thyristor triggering signal control circuit adopts the capacitor step-down rectifier circuit power supply, two inputs of capacitor step-down rectifier circuit directly are connected on the leakage switch interior phase line and zero line lead, an input that wherein is connected to decompression capacitor is connected on the zero line lead, another input is connected between the phase line inlet wire wiring pile of the negative electrode of three terminal bidirectional thyristor and leakage switch, on the decompression capacitor and met bleeder resistance R1.Three, the trigger current of three terminal bidirectional thyristor is taken from thyristor triggering signal control circuit, the core of thyristor triggering signal control circuit is a unidirectional thyristor, the trigger electrode of three terminal bidirectional thyristor is by diode VD5, VD4 links to each other with the anode of unidirectional thyristor, when leakage switch normally powers to the load, unidirectional thyristor is in off state, potential difference between its anode and negative electrode is big, make three terminal bidirectional thyristor acquisition trigger current and be in conducting state, work as electric leakage, get an electric shock, when overcurrent or overvoltage reach operating value, unidirectional thyristor becomes conducting by shutoff, potential difference diminishes between its anode and negative electrode, makes the three terminal bidirectional thyristor can not get trigger current and turn-offs.Four, thyristor triggering signal control circuit has partly adopted the unidirectional thyristor of trigger characteristic sensitivity, trigger current is less than 1mA, can directly the be leaked electricity control of electric shock sample circuit of the operating state of unidirectional thyristor, when the electric leakage electric shock promptly takes place, the induced current that is produced by zero sequence current mutual inductor is directly inputted to the trigger electrode of unidirectional thyristor, triggers unidirectional thyristor.Five, unidirectional thyristor anode-side in the thyristor triggering signal control circuit or cathode side have been connected in series reset button switch S 1; the contact of this switch is in closure state (being the normally-closed contact push-button switch) at ordinary times; when needing to power to the load again after the leakage switch protection action; press the reset button switch; unidirectional thyristor is turn-offed; make the conducting of three terminal bidirectional thyristor, leakage switch recovers to power to the load.Six, the overcurrent signal of sample circuit is extracted by current transformer TA2, also can be extracted by sampling resistor R6, and over-voltage protection function can optionally be accepted or rejected.Seven, the housing of this single-phase leakage switch can be independent housing, also can be the housing that is loaded on a shell with its electrical equipment of base together, and other electrical equipment is meant supply socket, electric fan, washing machine, refrigerator, instrument and meter and various control panels etc.

The utility model has reached design purpose; owing to adopted the break-make of three terminal bidirectional thyristor with contactless side's industry control system output voltage; the three terminal bidirectional thyristor can turn-off in 0.02 second fast when the electric leakage shock current reaches the protection operating value; cut off the power supply of get an electric shock electric leakage circuit and electrical appliance; thereby improved the safety coefficient of single-phase leakage switch,, simplified circuit owing to adopted the unidirectional thyristor of trigger characteristic sensitivity; help reducing cost, be convenient to tissue production.

Further describe below in conjunction with accompanying drawing.

Accompanying drawing 1 is the single-phase leakage switch theory diagram of no main contacts.

Accompanying drawing 2 is the single-phase gfci circuit schematic diagrams of being served as the no main contacts of overcurrent protection sampling by current transformer.

Accompanying drawing 3 is the single-phase gfci circuit schematic diagrams of being served as the no main contacts of overcurrent protection sampling by resistance.

Accompanying drawing 4 is single-phase leakage switch shell schematic diagrames of no main contacts.

Among the figure:

VS1: three terminal bidirectional thyristor.VS2, VS3: unidirectional thyristor.VD1-VD6, VD8: rectifier diode.VD7: light-emitting diode.C1-C4: capacitor.VR1, VR2: variable resistance.TA1: zero sequence current mutual inductor.TA2: current transformer.R5: piezo-resistance.R1-R4: resistance.R6: wire-wound resistor.S1: the normally-closed contact push-button switch, as reset switch.S2: the normally opened contact push-button switch, as experiment push-button switch (TesT).1, housing, 2, the electric power incoming line wiring pile, 3, outlet (output) wiring pile, 4, reset switch, 5, the test button switch, 6, mode indicator (light-emitting diode), 7, nameplate.

As shown in Figure 2, VS1 is the three terminal bidirectional thyristor, constitute the thyristor switch circuit by it, replace the mechanical tripping device in the existing leakage switch, VS1 must connect according to method shown in Figure 2, that is: the three terminal bidirectional thyristor must be connected on the interior phase line line of leakage switch, its negative electrode must be connected on the side near power supply phase line inlet wire wiring pile, (when adopting resistor to serve as the overcurrent sampling, the thyristor negative electrode links to each other with power supply phase line inlet wire wiring pile one side by the overcurrent sampling resistor, overcurrent sampling problem will be narrated in the back), its anode then by the phase line lead in the leakage switch on the iron core of zero-sequence transformer (electric leakage, electric shock sampling element) on the phase line outlet wiring pile that is connected in leakage switch behind some circles.The anode of thyristor can not be connected on that side near the electric power incoming line wiring pile.

Electric leakage electric shock sample circuit is made up of zero sequence current mutual inductor TA1, capacitor C3 and variable resistor VR1 etc.The used iron core of zero sequence current mutual inductor is annular, and its material can be silicon steel sheet, magnetic ferrites or amorphous material, and coiling on the annular core, elementary winding are phase line and zero line two-wire and around 1 to some circles, and secondary winding is the over thousands of circle of hundreds of circle to.When not having electric leakage and get an electric shock, the alternating current equal and opposite in direction in phase line and the zero line, direction is opposite, the magnetic flux vector that the zero-sequence transformer iron core is inducted and be zero, the miscarriage of secondary winding influence electricity is living.In when, electric leakage taking place with electric line or having the people to get an electric shock when, the leak shock electric current by phase line break down the position through leak, the electric shock approach goes into ground, this electric current will flow through from zero-sequence transformer through phase line, owing to it goes through ground, no longer the zero line through leakage switch flows back to, and causes the electric current in leakage switch phase line lead and the zero line lead not wait, and the phase line current is greater than neutral line current, making the magnetic flux of inducting in the zero-sequence transformer iron core no longer is zero, thereby induces electric current on secondary winding.This electric current is controlled the operating state of thyristor triggering signal control circuit by it, and then is influenced the break-make of three terminal bidirectional thyristor as the input signal of thyristor triggering signal control circuit.

The triggering signal control circuit of thyristor is made up of unidirectional thyristor VS2, VS3 and diode VD3-VD6 etc., adopted the unidirectional thyristor of trigger characteristic sensitivity, as P0102(1A, 400V), 2N6565(0.8A, 400V) and 2P4M(2A, 400V) etc., because their required trigger currents are little, generally below 1mA, the induced current that produces with zero sequence current mutual inductor just is enough to and it can be triggered, so circuit structure is fairly simple.This circuit work power is a direct current, is powered by the capacitor step-down rectifier circuit that C1, R1, VD1, VD2 and C2 etc. form.

The power supply of capacitor step-down rectifier circuit is directly taken from phase line and the zero line lead in the leakage switch, and capacitor C1 plays step-down and metering function, and VD1 and VD2 carry out rectification, and C2 filtering produces direct voltage, powers to thyristor triggering signal control circuit.As seen from the figure, in two lead-in wires of decompression capacitor C1, a lead-in wire links to each other with VD2 with rectifier diode VD1, another root lead-in wire is connected on the zero line lead of 220V alternating current process in the leakage switch (being a point among Fig. 2), this is a power input of capacitor step-down rectifier circuit, another power input of capacitor step-down rectifier circuit is to be connected on the phase line lead of 220V alternating current process in the leakage switch, tie point is between the negative electrode and electric power incoming line phase line wiring pile of three terminal bidirectional thyristor (being the C point among Fig. 2), tie point can not be chosen in the anode-side of three terminal bidirectional thyristor, otherwise the circuit meeting can't operate as normal.Have only according to the connection shown in the accompanying drawing 2; could guarantee thyristor triggering signal control circuit leakage switch normally power to the load and the state implementing to protect under can both obtain normal direct current supply, undertake electric charge with decompression capacitor C1 and the resistance R 1 that connects and let out the effect effect.When electrical network stops when leakage switch power supply (as outage or people for cutting off the electricity supply), R1 can provide to the electric charge that C1 go up to store release by way of, can prevent from when restoring electricity to damage, can ensure the operate as normal of circuit element safety and circuit because of the circuit element that voltage remaining on the capacitor and 220V alternating current superposition cause.

The input signal of thyristor triggering signal control circuit is provided by electric leakage electric shock sample circuit, and signal is by the trigger electrode input of unidirectional thyristor VS2.In the circuit, VD3 is the trigger electrode reverse protection diode of VS2, and C3 plays anti-interference effect, and VR1 is that the protection point is adjusted variable resistor.When not having electric leakage electric shock situation, the zero sequence current mutual inductor in the electric leakage electric shock sample circuit does not have induced current to produce, and output voltage is zero.Unidirectional thyristor VS1 can not get the trigger voltage electric current, is in off state.Its anode (d point) is in high potential, capacitor step-down rectifier circuit provides trigger current by the b point → R2 in the accompanying drawing 2 → d point approach that (this moment, push-button switch S1 contact was closed) → VD4 → VD5 → VS1 trigger electrode → C is ordered to the three terminal bidirectional thyristor, the VS1 conducting, the phase line inlet wire wiring pile → VS1 negative electrode of 220V alternating current by electrical network phase line → leakage switch end of incoming cables → (VS1 anode → pass the zero line lead of TA2 → pass TA1 → leakage switch output phase line wiring pile → load → leakage switch output zero line wiring pile → in leakage switch through the phase line lead to wear back the approach of TA1 → leakage switch inlet wire zero line wiring pile → electrical network zero line and form the loop normally powers to the load.

Starting shooting moment, had only the VS1 conducting, just had electric current and in leakage switch, flow through phase line and the zero line lead, so, before the VS1 conducting, zero sequence current mutual inductor can not have induced current output, and VS2 can only turn-off in start moment, thus reliably conducting of VS1 when having guaranteed start, therefore, this device does not need to manually boot as long as a connection 220V AC power just powers to the load immediately.

When electric leakage takes place or has the people to get an electric shock in the following position of leakage switch output, the zero-sequence transformer secondary winding will produce induced current, also can produce certain voltage, if electric leakage is light, the table resistance that gets an electric shock is big, the induced current of the secondary generation of zero-sequence transformer is little, voltage is low, is not enough to trigger VS2, and VS2 still turn-offs, VS1 continues conducting, and leakage switch still continues power supply.If electric leakage is serious or electric shock person's resistance is little, shock current is big.The leak shock electric current reaches or is higher than protects action criteria (there is the corresponding standard regulation in country); the VS2 conducting that just is triggered; its anode (d point) is electronegative potential; VD4, VD5 can not conductings; VS1 can not get trigger current and turn-offs; cut off the phase line path, the following position of leakage switch phase line output terminal is all not charged, thereby has ensured personal and with the safety of electric line.

After cutting off the phase line path, the usefulness electric line and the load at the following position of leakage switch output do not have electricity, have not just leaked electricity with shock current naturally yet.Like this, the secondary burning group of zero-sequence transformer has not just had induced current yet, and unidirectional thyristor VS2 has lost triggering signal, and still, because VS2 is direct current supply, as long as its triggering and conducting, no matter whether triggering signal exists, it all goes down conducting always.Unless cut off its electric current, it could recover off state.So after this leakage switch protection action, it can reliablely and stablely keep guard mode, guarantees that output does not have.

Broken away from the electric shock position if got rid of leak current fault or electric shock person, just can restore electricity.The normally-closed contact push-button switch S1 of VS2 anode polyphone just works the effect of restoring electricity, i.e. reset switch in the circuit.As long as hand clicks S1, normally-closed contact disconnects, and the electric current that flows through VS2 is cut off, and VS2 turn-offs immediately.At this moment, its anode is high potential again, and like this, VS1 can obtain trigger current again and recover conducting, and the phase line path is connected, and leakage switch recovers to power to the load.If the somebody gets an electric shock or electric leakage, leakage switch will be implemented protection again.

In the accompanying drawing 2, R3 and VD7, VD8 etc. play the operating state indicative function.Wherein, R3 plays the step-down metering function; VD7 is a light-emitting diode, and when the leakage switch normal power supply, VD7 is luminous.After the protection action, output voltage is zero, and VD7 extinguishes.VD8 provides path for the alternating current negative half period, plays protection VD7.

The same with common leakage switch, this leakage switch also is provided with test (Test) button, be the S2 in the accompanying drawing 2, when using leakage switch, (as one month) at regular intervals, will press S2, make S2 normally opened contact closure, can action message by the simulation leakage current check leakage switch that flows through R4.

The utlity model has overvoltage protection and excess current protective function, the overvoltage sample circuit is made of piezo-resistance R5.R5 is connected in parallel on test button S2 and the R4.Line voltage just often; piezo-resistance is high-impedance state; almost there is not electric current to flow through; if electrical network generation overvoltage; such as; line voltage raises suddenly because of certain factor; or zero line is received on another phase line of three-phase electricity, make circuit become the two-phase power supply, the resistance of piezo-resistance will reduce immediately; by mistake there is electric current to flow through from it; form the leakage current of simulation,, make the leakage switch action to making zero-sequence transformer TA1 secondary winding produce induced current; cut off output voltage, following circuit and the electrical equipment of protection leakage switch.

The overcurrent sample circuit is made of current transformer TA2, capacitor C4 and variable resistor VR2 etc.The elementary winding of TA2 can be in phase line or the zero line any one (that adopt in the accompanying drawing 2 is in phase line or the zero line any one), can adopt punching or only around a circle.

When electric current flow through the elementary winding of instrument transformer TA2, its secondary winding will produce induced current.The trigger electrode of this electric current supply and VS2 and the unidirectional thyristor VS3 that connects.At ordinary times, TA2 time grade of electric current that provides is minimum, is not enough to trigger VS3, and VS3 is in off state, does not influence the work of VS2, also can not exert an influence to the d point voltage.If overcurrent takes place in the following position of leakage switch output; the electric current that the TA2 secondary winding produces obviously increases; the pressure drop that produces on VR2 is also big; if greatly to VS3 is triggered; VS3 just enters conducting state by shutoff; d point current potential is dragged down; thereby VD4 and VD5 are turn-offed, and interruption makes VS1 become shutoff by conducting to the trigger current that VS1 provides; implement overcurrent protection; VR2 is a variable resistor of adjusting overcurrent protection point usefulness, and when resistance was big, the protection operating value was low; resistance hour, protection operating value height.

The overcurrent sampling element both can adopt current transformer, also can adopt resistance sampling.See accompanying drawing 3 with the circuit arrangement of resistance sampling.Between the negative electrode of three terminal bidirectional thyristor and C point (being capacitor step-down rectifier circuit and the junction of phase line lead), be connected with a little resistance resistance wire R6, with this resistance as the overcurrent sampling element.During normal electricity consumption, on the resistance R 6 pressure drop very little, can not make the VS3 triggering and conducting.When overcurrent took place, pressure drop increased on this resistance, thereby makes the VS3 triggering and conducting, and then caused VS1 to turn-off, and implemented overcurrent protection.In the circuit, VD4 and VD5 also can replace with a low pressure voltage-stabiliser tube (following as 5.1 volts).

According to above-mentioned design, inventor's a embodiment has made a kind of single-phase leakage switch that does not have main contacts, its overall dimensions as shown in Figure 4, housing is cuboid substantially, length is 90 millimeters, wide is 70 millimeters, height is 50 millimeters, shell material is the good plastics of insulation property, circuit is loaded in the housing separately, side on housing is provided with the inlet wire wiring pile that is connected with the 220V power supply, the mark of " phase line " and " zero line " is arranged near the inlet wire wiring pile, and the housing opposite side is provided with the outlet wiring pile that is connected with load, and the mark of " phase line " and " zero line " is also arranged, surface of shell is equipped with the test button switch, the button switch that resets, mode indicator (light-emitting diode) and nameplate, position, housing bottom surface is provided with and installs and fixes the hole, fix with screw for being installed on wall and other object, the single-phase leakage switch circuit of this no main contacts is simplified, and dependable performance is active in one's movements, can in 0.02 second, turn-off fast, cut off the power supply of electric shock circuit and electrical equipment,, be convenient to install because volume is little, can be widely used in supply socket, electric fan, washing machine, household electrical appliance and instrument and meters such as refrigerator, control panel, it is respond well to ensure public security.

Claims (8)

1, a kind of single-phase leakage switch of forming by housing and circuit, it is characterized in that adopting the three terminal bidirectional thyristor, break-make with contactless mode control output voltage, entire circuit is installed in the housing, entire circuit comprises by electric leakage electric shock sample circuit, overcurrent overvoltage sample circuit, capacitor step-down rectifier circuit, several parts such as thyristor triggering signal control circuit and thyristor switch are formed, its electric leakage electric shock sample circuit is by zero sequence current mutual inductor TA1, capacitor C3, compositions such as variable resistor VR1, the overcurrent sample circuit is by current transformer TA2, compositions such as capacitor C4 and variable resistor VR2, capacitor step-down rectifier circuit is by capacitor C 1, C2, resistance R 1 and rectifier diode VD1, compositions such as VD2, thyristor triggering signal control circuit is by unidirectional thyristor VS2, VS3, compositions such as diode VD3-VD6, thyristor switch is made up of three terminal bidirectional thyristor VS1, housing is provided with power supply turnover line wiring pile, be provided with " phase line " and " zero line " mark near the wiring pile, also be provided with reset switch on the housing, the test button switch, mode indicator and nameplate, connection between each part of whole leakage switch makes when unmanned electric shock and leakage current during less than leakage switch operating current value, three terminal bidirectional thyristor VS1 in the leakage switch is conducting, leakage switch normally powers to the load, when getting an electric shock or leakage current when meeting or exceeding leakage switch operating current value, three terminal bidirectional thyristor VS1 turn-offed in 0.02 second fast, stop to power to the load, the following position of leakage switch output connection stake is in safe electroless state, fault is pressed reset button switch S 1 and can be recovered normal power supply after eliminating.

2, single-phase leakage switch according to claim 1, it is characterized in that the three terminal bidirectional thyristor that said control circuit break-make is used must be connected on the phase line lead of leakage switch, its negative electrode directly or by the overcurrent sampling resistor links to each other with leakage switch phase line inlet wire wiring pile, its anode by the phase line lead in the leakage switch on the zero sequence current mutual inductor iron core around some circles, and then link to each other with phase line outlet wiring pile.

3, leakage switch according to claim 1, it is characterized in that said thyristor triggering signal control circuit adopts the capacitor step-down rectifier circuit power supply, two inputs of capacitor step-down rectifier circuit directly are connected on the leakage switch interior phase line and zero line lead, an input that wherein is connected to decompression capacitor is connected on the zero line lead, another input is connected between the phase line inlet wire wiring pile of the negative electrode of three terminal bidirectional thyristor and leakage switch, on the decompression capacitor and met bleeder resistance R1.

4, single-phase leakage switch according to claim 1, the trigger current that it is characterized in that said three terminal bidirectional thyristor is taken from thyristor triggering signal control circuit, the core of thyristor triggering signal control circuit is a unidirectional thyristor, the trigger electrode of three terminal bidirectional thyristor links to each other with the anode of unidirectional thyristor by diode, when leakage switch normally powers to the load, unidirectional thyristor is in off state, potential difference between its anode and negative electrode is big, make three terminal bidirectional thyristor acquisition trigger current and be in conducting state, work as electric leakage, get an electric shock, when overcurrent or overvoltage reach operating value, unidirectional thyristor becomes conducting by shutoff, potential difference diminishes between its anode and negative electrode, makes the three terminal bidirectional thyristor can not get trigger current and turn-offs.

5, single-phase leakage switch according to claim 1, it is characterized in that said thyristor triggering signal control circuit has partly adopted the unidirectional thyristor of trigger characteristic sensitivity, trigger current is less than 1mA, can directly the be leaked electricity control of electric shock sample circuit of the operating state of unidirectional thyristor, when the electric leakage electric shock promptly takes place, the induced current that is produced by zero sequence current mutual inductor is directly inputted to the trigger electrode of unidirectional thyristor, triggers unidirectional thyristor.

6, according to the single-phase leakage switch described in claim 1 or 5; it is characterized in that unidirectional thyristor anode-side or cathode side in the described thyristor triggering signal control circuit have been connected in series reset button switch S 1; the contact of this switch is in closure state (being the normally-closed contact push-button switch) at ordinary times; when needing to power to the load again after the leakage switch protection action; press the reset button switch; unidirectional thyristor is turn-offed; make the conducting of three terminal bidirectional thyristor, leakage switch recovers to power to the load.

7, single-phase leakage switch according to claim 1 is characterized in that said overcurrent signal is extracted by current transformer TA2, also can be extracted by sampling resistor R6.

8, single-phase leakage switch according to claim 1, it is characterized in that said housing, it can be independent housing, also can be the housing that is loaded on a shell with its electrical equipment of base together, other electrical equipment be meant supply socket, electric fan, washing machine, refrigerator, instrument and meter and various control panels etc.

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