CN103730784B - A kind of socket eliminating electric spark - Google Patents

Abstract

The invention relates to a socket for eliminating electric sparks, including a power socket and a socket provided on an electrical appliance for taking electricity, which can be applied to take electricity for appliances in inflammable and explosive places, or be used for the design of taking electricity for explosion-proof appliances. It is characterized in that: at least one group of socket contact pieces has a first socket contact piece, a second socket contact piece and a current limiting resistor, and the second socket contact piece is connected to the first socket contact piece through the current limiting resistor. Further, the current limiting resistor adopts a positive or negative temperature coefficient thermistor. The beneficial effect is: 1. As a power socket, it can eliminate the electric spark generated by the plug insertion and pulling out, avoid the contact piece from being eroded and burned, and is suitable for use in explosion-proof places; 2. As an explosion-proof electrical outlet, it can effectively prevent the power plug from being inserted, Electric sparks when unplugged.

Description

A socket for eliminating electric sparks

technical field

The invention relates to a socket for eliminating electric sparks, including a power socket and a socket arranged on an electrical appliance for taking power, which can be applied to take electricity for electric appliances in inflammable and explosive places, or be used for the design of taking electricity for explosion-proof electrical appliances.

Background technique

The moment the electrical plug is inserted into the socket, due to the existence of a large starting current, sparks and heat will be generated at the contact point. With the stable contact between the plug and the socket contacts, the sparks and heat will disappear. When the electrical plug is pulled out When using a socket, often due to the existence of the load, sparks will also be generated at the moment when the contacts are separated. Due to the existence of electric sparks, the socket contacts and plug contacts of the socket will be continuously eroded, and in severe cases, the socket contacts and plugs will be burned. In addition, the sparks and heat of the power contacts in flammable and explosive places can easily cause explosion accidents.

With the application of new technologies in petroleum and petrochemical industries, especially the application of information-based computers, such as: online analysis instruments, computers, PLCs, operating stations, rechargeable flashlights, wireless walkie-talkies, notebook computers, etc. in daily use, will encounter power-taking problems. Or charging problems, because the existing charging adapters do not consider the explosion-proof design (or it is impossible to carry out the explosion-proof design), contact sparks will be generated at the moment of plugging in or pulling out the socket, if it is used directly in the explosion-proof area, it may cause an explosion accident. The invention of the electric appliance socket can effectively eliminate the electric spark caused by the moment the electric appliance receives electricity.

Since the starting current of electrical products is generally relatively large, the surge current generated will cause harm to the electrical appliances themselves and interfere with the normal operation of the power grid.

Contents of the invention

The idea of the present invention is: when the plug is inserted into the socket, the instantaneous current passing between the contact piece of the socket and the contact piece of the plug is limited to a small range by the current limiting resistor, and the sudden change of the current is prevented by the current limiting resistor when the plug is pulled out of the socket , thus avoiding the generation of electric sparks, thereby protecting the contacts, and suitable for use in explosion-proof places.

Technical scheme of the present invention is:

A socket for eliminating electric sparks, including a socket contact path, is characterized in that: at least one set of socket contact paths has a first socket contact, a second socket contact, and a current limiting resistor, and the second socket contact passes through The current limiting resistor is connected to the contact piece of the first socket.

The above-mentioned socket for eliminating electric sparks is characterized in that: a resettable fuse is also connected in series in the circuit of the current-limiting resistor.

The above-mentioned socket for eliminating electric sparks is characterized in that: the self-recovery fuse is a polymer organic PTC.

The described socket for eliminating electric sparks is characterized in that: said set of socket contact pieces also has a third socket contact piece and another current-limiting resistor connected to said third socket contact piece, said The other end of the other current-limiting resistor is connected to the contact piece of the first socket.

The socket for eliminating electric sparks is characterized in that: the current-limiting resistor is a negative temperature coefficient thermistor.

The socket for eliminating electric sparks is characterized in that: the negative temperature coefficient thermistor is an NTC thermistor.

The above-mentioned socket for eliminating electric sparks is characterized in that: the current-limiting resistor is a positive temperature coefficient thermistor.

The socket for eliminating electric sparks is characterized in that: the positive temperature coefficient thermistor is a PTC thermistor.

The electrical spark elimination socket is characterized in that: the nominal value range of the current limiting resistor is 0.5K~5K.

The socket for eliminating electric sparks is characterized in that: the nominal value range of the current limiting resistor is 0.5 ohms to 100 ohms.

The described socket for eliminating electric sparks is characterized in that: the set of socket contacts has more than three socket contacts and corresponding current-limiting resistors connected to the socket contacts, and the corresponding current-limiting resistors The other end is connected with the contact piece of the first socket.

The beneficial effects of the present invention are as follows: 1. As a power socket, it can eliminate electric sparks caused by plug insertion and pulling out, avoid contact erosion and burnout, and is suitable for use in explosion-proof places; 2. As a power socket for explosion-proof electrical appliances, it can effectively prevent power Electric sparks generated when the plug is inserted and pulled out; 3. Eliminate the harm of surge current to electrical appliances and avoid interfering with the normal operation of the power grid.

Description of drawings

Figure 1 is a front-end rectification circuit of an existing switching power supply.

Fig. 2 is a diagram showing changes in electrical parameters during the contact process of a conventional socket and plug.

Fig. 3 is a structure diagram of the power socket with two contact blades of the present invention.

Fig. 4 is a contact state diagram of the second socket contact piece and the plug contact piece of the two-contact piece power socket of the present invention (corresponding to the period t1-t2 in Fig. 6 ).

Fig. 5 is a contact state diagram of the first socket contact and the plug contact of the two-contact power socket of the present invention (corresponding to the period t3-t4 in Fig. 6 ).

Fig. 6 is a graph showing changes in electrical parameters during the contact process between the socket and the plug of the present invention (two contacts).

Fig. 7 is a structure diagram of the present invention, which is a three-contact power socket of the present invention.

Fig. 8 is a contact state diagram of the third socket contact piece and the plug contact piece of the three-contact piece power socket of the present invention.

Fig. 9 is a diagram showing the contact state of the second socket contact piece and the plug contact piece of the three-contact piece power socket of the present invention.

Fig. 10 is a contact state diagram of the first socket contact piece and the plug contact piece of the three-contact piece power socket of the present invention.

Fig. 11 is a structural diagram of an explosion-proof electrical socket of the present invention.

Fig. 12 is a diagram showing the contact state of the second socket contact piece and the plug contact of the explosion-proof electrical socket of the present invention.

Fig. 13 is a contact state diagram of the first socket contact piece and the plug contact of the explosion-proof electric appliance power-taking socket of the present invention.

Fig. 14 is an embodiment of a self-recovery fuse connected in series in the current-limiting resistor circuit of the present invention.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Figure 1 is a front-end rectification circuit of an existing switching power supply. In Figure 1, 220V AC is connected to the rectifier circuit through the fuse F, a bridge full-wave rectifier circuit composed of D1, D2, D3, and D4 rectifier diodes, and capacitor C is a filter capacitor. At present, most power supplies use switching power supplies, such as laptop power supplies and mobile phone charging power supplies. The general power is tens of watts, the rated current is about several hundred milliamps, and the equivalent resistance is about 1K. For example, when the adapter power plug of a laptop is inserted into the power socket, there will be a popping sound accompanied by electric sparks, because the filter capacitor is generally large, and a large current will be generated at the moment the filter capacitor is charged.

In addition, the power-on of high-power electrical appliances will also generate electric sparks.

The starting current of electrical products is generally relatively large, which will generate electric sparks. At the same time, the surge current will cause harm to the electrical appliances themselves and interfere with the normal operation of the power grid.

Fig. 2 is a diagram showing changes in electrical parameters during the contact process of a conventional socket and plug. Assuming that a switching power supply is plugged into a traditional power socket, 201 is a diagram of the voltage change between the contacts of the power socket and the plug contact, and 202 is a diagram of the current passing through. The voltage before the contacts of the power socket and the plug contact is 220V (0- t1 time period), t1 is the contact time point between the contact piece of the power socket and the plug contact piece. At this time, the passing current immediately reaches the maximum point Imax, and then with the charging of the filter capacitor C, the current drops, and the final current is the rated current Ir of the electrical appliance. Assuming that the equivalent rated resistance of the electrical appliance is Rr, then: Ir=220/Rr, the contact voltage drop between the contact piece of the power socket and the contact piece of the plug after the point t2 stabilizes is 0, that is, the contact is stable.

Fig. 3 is a structure diagram of the power socket with two contact blades of the present invention. In Fig. 3, 101 is a power socket, and there are two groups of socket contact pieces paths in the power socket, one group is the L path, and the other group is the N path, the L path in the power socket 101 includes the first socket contact piece 102, and the current limiting Resistor 103 (resistance value R), second socket contact piece 104, second socket contact piece 104 is connected to first socket contact piece 102 through current limiting resistor 103, first socket contact piece 102 is connected to L terminal of power supply (live wire In the same way, the other group is the N channel, which is connected to the N (neutral terminal) terminal of the power supply. The structure of the N channel and the L channel can be symmetrical and the same, or the N channel current limiting resistor can be removed and the first socket contact piece It is directly connected to the contact piece of the second socket (indicated by the dotted line in the figure). 105 is a conventional plug, 106 is a plug contact (L end), and 107 is a plug lead. The grounding contact path in the power socket of the present invention is not marked.

A socket for eliminating electric sparks, including a socket contact path, is characterized in that: at least one set of socket contact paths has a first socket contact, a second socket contact, and a current limiting resistor, and the second socket contact passes through The current limiting resistor is connected to the contact piece of the first socket.

Fig. 4 is a contact state diagram of the second socket contact piece and the plug contact piece of the two-contact piece power socket of the present invention (corresponding to the period t1-t2 in Fig. 6 ).

Fig. 5 is a contact state diagram of the first socket contact and the plug contact of the two-contact power socket of the present invention (corresponding to the period t3-t4 in Fig. 6 ).

Fig. 6 is a graph showing changes in electrical parameters during the contact process between the socket and the plug of the present invention (two contacts). t1 – The time period of t2 corresponds to the state in Figure 4. When the contact piece of the plug contacts with the contact piece of the second socket, the maximum charging current will not exceed I=220/R, regardless of the N-terminal current limiting resistor (that is, the dotted line scheme), generally The on-off current for generating electric sparks is above 100mA. If R=3K is selected, the instantaneous maximum current is 220V/3K=73mA, which is smaller than the on-off current for generating electric sparks. The voltage between contacts during t2-t3 is U=220 *R/(R+Rr), the current is I=220/(R+Rr). The time period t3-t4 corresponds to the state shown in Figure 5. When the contact piece of the plug continues to be inserted into contact with the contact piece of the first socket, the voltage between the contacts drops to 0, and the passing current is the normal rated current Ir of the electrical appliance.

Fig. 7 is a structure diagram of the present invention, which is a three-contact power socket of the present invention. In consideration of further reducing the voltage gradient between the contacts, the number of socket contacts and current-limiting resistors can be increased. In FIG. 7 , a current-limiting resistor 701 and a third socket contact 702 are added. Further, the number of socket contacts and current-limiting resistors can continue to be increased, and the number is not limited.

The described socket for eliminating electric sparks is characterized in that: said set of socket contact pieces also has a third socket contact piece and another current-limiting resistor connected to said third socket contact piece, said The other end of the other current-limiting resistor is connected to the contact piece of the first socket.

The described socket for eliminating electric sparks is characterized in that: the set of socket contacts has more than three socket contacts and corresponding current-limiting resistors connected to the socket contacts, and the corresponding current-limiting The other end of the resistor is connected to the contact piece of the first socket.

Fig. 8 is a contact state diagram of the third socket contact piece and the plug contact piece of the three-contact piece power socket of the present invention.

Fig. 9 is a diagram showing the contact state of the second socket contact piece and the plug contact piece of the three-contact piece power socket of the present invention.

Fig. 10 is a contact state diagram of the first socket contact piece and the plug contact piece of the three-contact piece power socket of the present invention.

Fig. 11 is a structural diagram of an explosion-proof electrical socket of the present invention. Considering that some of the existing explosion-proof electrical appliances use socket power supply, such as explosion-proof notebooks and explosion-proof communication equipment, the power-taking socket of explosion-proof electrical appliances is designed to have at least two socket contact structures, 1101 is the power-taking socket of explosion-proof electrical appliances, and 1102 is the positive contact , 1103 is the first socket contact, 1104 is the current limiting resistor, 1105 is the second socket contact, 1106 is the plug, 1107 is the power adapter.

Fig. 12 is a diagram showing the contact state of the second socket contact piece and the plug contact of the explosion-proof electrical socket of the present invention.

Fig. 13 is a contact state diagram of the first socket contact piece and the plug contact of the explosion-proof electric appliance power-taking socket of the present invention.

The resistance value of the current-limiting resistor described in the present invention is not used as a limiting condition of the present invention, nor is the number of contacts of the socket of the present invention taken as a limiting condition of the present invention.

The current limiting resistor of the present invention is one or a combination of the following: a fixed resistor, a negative temperature coefficient thermistor, and a positive temperature coefficient thermistor. Negative temperature coefficient thermistors such as NTC thermistors, positive temperature coefficient thermistors such as PTC thermistors, PTC thermistors include resettable fuses, which are polymer organic PTCs.

The current-limiting resistor adopts a negative temperature coefficient thermistor, that is, the resistance decreases as the temperature increases, such as the existing power NTC thermistor, when the second socket contact piece and the plug contact piece contact the NTC thermistor instantly The resistance value is the largest, and the passing current is the smallest. As the current passing temperature increases, the resistance value decreases, and the final current reaches the maximum value. Generally, the final resistance of the NTC thermistor is relatively small, and the passing current is close to the rated current of the load. Contact with the first socket contact piece, the NTC thermistor is short-circuited and loses its effect, and the plug and socket formally contact and work normally. Here, because the NTC thermistor only works at the moment when the plug is inserted into the socket, it does not work at ordinary times, thereby prolonging the service life of the NTC thermistor. For example: NTC thermistor selects the existing 3.3K nominal value, B constant 3950K, the resistance value is 3.3K when the temperature is 25 degrees, when the temperature rises to 125 degrees, the resistance value is 0.113K, through calculation (regardless of the load) : The current is 220V/3.3K=66.7 mA at 25 degrees, and the current is 220V/0.113K=1947 mA at 125 degrees. Considering the existence of the load, the maximum current when the contact piece of the second socket contacts the plug does not exceed 66.7 mA, as the temperature of the NTC thermistor rises, the resistance decreases and the passing current increases. The maximum current will not exceed the rated current of the load. When the contact piece of the first socket contacts the contact piece of the plug, the load obtains the normal rated current, and at the same time NTC thermistor stopped working. It can be seen that the whole process effectively reduces the contact current, and avoids the charging current caused by the capacitor and the surge current caused by the startup of the electrical appliance.

The current-limiting resistor adopts a positive temperature coefficient thermistor, that is, the resistance increases as the temperature increases, such as the existing PTC thermistor, when the contact piece of the second socket contacts the contact piece of the plug, the resistance value of the PTC thermistor is the smallest , the passing current is the largest, and the resistance value increases with the increase of the current passing temperature. At this time, the charging process of the capacitor in the electrical appliance has been completed, and the PTC thermistor is short-circuited as the contact piece of the plug contacts with the contact piece of the first socket. Loss of function, the plug and socket formally contact and work normally. The advantage of using a PTC thermistor is that it can avoid overheating of the current limiting resistor that may be caused when the plug of a high-power electrical appliance is inserted into the socket. For example: PTC thermistor selects the existing 3.3K nominal value, the temperature coefficient of resistance is 10[[%]]/℃, the resistance value is 3.3K when the temperature is 25 degrees, and the resistance value is about 22K when the temperature rises to 45 degrees , through calculation (without considering the load): the current is 220V/3.3K=66.7 mA at 25 degrees, and the current is 220V/22K=10 mA at 45 degrees. Considering the existence of the load, when the second socket contact and plug The maximum current at the moment of contact does not exceed 66.7 mA. As the temperature of the PTC thermistor rises, the resistance increases. When the temperature is 45 degrees, the current is about 10 mA. When the socket contacts and plug contacts are in contact, the load obtains the normal rated current, and the PTC thermistor stops working at the same time. It can be seen that the whole process effectively reduces the contact current, and avoids the charging current caused by the capacitor and the surge current caused by the startup of the electrical appliance.

Fig. 14 is an embodiment of a self-recovery fuse connected in series in the current-limiting resistor circuit of the present invention. The self-recovery fuse is a kind of polymer organic PTC resistor. The resistance value is extremely small below the calibration temperature. When the self-heating or the ambient temperature reaches the calibration temperature, its resistance value rises sharply to play the role of a fuse. The self-recovery fuse can be changed by changing its resistance value. Its own heat dissipation changes its thermal inertia to realize the delay time of current blocking. 103 in Figure 14 is a current-limiting resistor, which can be a fixed resistor, or an NTC thermistor, or a PTC thermistor, and 1401 is a resettable fuse. Install the current-limiting resistor 103 and the resettable fuse 1401 together, and select the calibration temperature ( For example, for a self-recovery fuse at 60 degrees), generally the contact time between the plug contact and the second socket contact 104 is very short, so the current limiting resistor 103 does not generate much heat. If the plug contact and the second socket contact 104 contact In the case of a long time, when the temperature of the current limiting resistor 103 reaches 60 degrees, the resettable fuse 1401 will block the current. 1402 in FIG. 14 is another socket contact piece of N channel, and this socket contact piece is a straight-through socket contact piece.

Assuming that the rated equivalent resistance of the electrical appliance is Rr and the voltage is 220V, the power dissipation of the current limiting resistor R is: R*220^2*(R+Rr) ^ (-2), due to the different power of the electrical appliances, the rated equivalent resistance of the electrical appliances is also different. Considering that the current power supply of notebook computers is 10W~100W, the nominal value of the current limiting resistor is selected to be 0.5K~5K. The power is about 10W~100W, and the nominal temperature of the self-recovery fuse is selected as 60 degrees to 100 degrees.

As a specific implementation plan of a power cord board: set up power socket jacks with different powers, such as within 500W, select the nominal value of the current limiting resistor in the range of 0.5K~5K, for example, choose a fixed resistor of 3.3K; For power appliances (500W~2500W), select the nominal value of the current-limiting resistor in the range of 0.5 ohm to 100 ohm. For example, choose a 30 ohm NTC thermistor (model 30D-9), and the residual resistance is about 1 ohm.

Claims (5)

1. eliminating a socket for electric spark, including socket contact sheet path, it is characterized in that: least one set socket contact sheet path has the first socket contact sheet, the second socket contact sheet, current-limiting resistance, described second socket contact sheet is connected by described current-limiting resistance and the first socket contact sheet；

One group of described socket contact sheet path also has the 3rd socket contact sheet and is connected to another current-limiting resistance on described 3rd socket contact sheet, and another current-limiting resistance other end described and the first socket contact sheet are connected；

Described current-limiting resistance is negative tempperature coefficient thermistor.

A kind of socket eliminating electric spark the most according to claim 1, is characterized in that: also concatenate resettable fuse in the circuit of described current-limiting resistance.

A kind of socket eliminating electric spark the most according to claim 2, is characterized in that: described resettable fuse is macromolecule organic PTC.

A kind of socket eliminating electric spark the most according to claim 1, is characterized in that: described negative tempperature coefficient thermistor is NTC thermistor.

5. according to a kind of socket eliminating electric spark described in claim 1 or 2 or 3 or 4, it is characterized in that: one group of described socket contact sheet path has more than three socket contact sheets and the corresponding current-limiting resistance being connected on described socket contact sheet, the described corresponding current-limiting resistance other end and the first socket contact sheet to be connected.