A pocket-sized air switch characteristic detection device

Abstract

The present invention discloses a pocket-sized air switch characteristic detection device, comprising an AC millivoltmeter, a protective resistor, an active power meter, a clamp-type transformer, a metal corkscrew, a spring contact, an infrared optical fiber, a germanium glass optical lens and an electric signal timer; one input end of the AC millivoltmeter is connected to a metal corkscrew through a protective resistor, and the other input end is directly connected to another metal corkscrew; the voltage signal end of the active power meter is connected in parallel with the two signal input ends of the AC millivoltmeter, and the current signal end is connected in series with the signal input end of the electric signal timer, and is connected to the secondary winding of the clamp-type transformer. The heads of the two metal corkscrews are provided with spring contacts, and an infrared optical fiber is provided at the center of one of the metal corkscrews, one end of the infrared optical fiber is connected to the spring contact, and the other end is connected to the germanium glass optical lens. The device of the present invention has the characteristics of convenient operation, light weight, live detection, arc extinguishing performance detection, and low cost.

Description

Technical Field

[0001] The invention relates to electric power instruments and meters, and in particular to a pocket-sized air switch characteristic detection device. Background Art

[0002] The air switch is one of the core components of the power supply system of the power plant, and is the basis for ensuring the normal operation of various auxiliary machines. Due to the low voltage level and many components of the power supply system, especially the air switch, its technical characteristics are rarely tested, and the detection method is sometimes unscientific and incomplete. In the high temperature season in summer, the air switch suddenly fails and burns or trips by mistake, causing the important auxiliary machines to lose power. Although the failure rate of air switches and contactors is not high, once the fault trips by mistake or the contacts stick and do not work, it may have a serious impact on the normal operation of the auxiliary equipment, and then cause a major accident. However, under the current conditions, there are almost no methods and habits for power-off verification or live detection of air switches in important circuits. Therefore, if a device that can perform live inspection of the operating conditions of air switches can be developed, and the operating conditions of air switches and contactors in important circuits can be regularly detected, it will help greatly improve the operating reliability and economy of power plant units.

[0003] The existing technology generally adopts a tripping scheme based on a large current generator. However, this scheme has the following shortcomings. First, it is inconvenient to use. The air switches in power plants are installed in large numbers, and the large current generator is very heavy. A 1000A large current generator weighs more than 30 kilograms, which brings great inconvenience to the mobile detection work on site. Secondly, it is impossible to test online. There are a large number of air switches. Relying on the short time of power outage and maintenance of the unit for detection is completely inadequate in terms of manpower and material resources. It is necessary to have the ability to detect online during operation with power. Secondly, it is impossible to detect the arc extinguishing ability of the switch. The existing technology can measure the tripping time of the switch through a time relay or a cumulative timer, but it cannot detect the arc extinguishing ability of the switch. If the arc extinguishing ability of the switch is insufficient, it will cause the contacts to stick together when the switch trips and cannot trip, resulting in a serious accident of the upper power supply tripping. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a pocket-sized air switch characteristic detection device, which has the characteristics of convenient operation, light weight, live detection, arc extinguishing performance detection, and low cost.

[0005] The technical solution of the present invention is:

[0006] A pocket-sized air switch characteristic detection device comprises an AC millivoltmeter, a protective resistor, an active power meter, a clamp-type mutual inductor, a metal snake tube, and an electric signal timer;

[0007] One signal input end of the AC millivoltmeter is connected in series with a protective resistor and then connected to one of the metal bellows, and another signal input end of the AC millivoltmeter is directly connected to another of the metal bellows; the voltage signal end of the active power meter is connected in parallel with the two signal input ends of the AC millivoltmeter; the current signal end of the active power meter is connected in series with the signal input end of the electrical signal timer and connected to the secondary winding of the clamp-on transformer.

[0008] Preferably, the two metal bellows and the clamp-on mutual inductor are arranged on the same side of the housing of the pocket-sized air switch characteristic detection device.

[0009] Preferably, the two metal bellows are provided with spring contacts at their heads, and an axial infrared optical fiber is provided at the center of one of the metal bellows, one end of the infrared optical fiber is connected to the spring contact, and the other end is connected to a germanium glass optical lens.

[0010] Preferably, the power input terminals of the AC millivoltmeter, active power meter and electrical signal timer are connected to a battery.

[0011] The advantages of the present invention are:

[0012] 1. Low cost, the price is only about one tenth of the existing technology. The present invention uses existing conventional components such as millivoltmeter, active power meter, electric signal timer, etc., combined with a specially designed detection circuit, and directly uses the working current to detect the air switch in operation, without the need for an additional current generator, thereby greatly reducing the cost.

[0013] 2. Lightweight and easy to move. Since the present invention does not require an additional current generator, the weight of the entire instrument is greatly reduced, solving the shortcomings of the prior art equipment that is bulky and inconvenient to move. The entire machine is only the size of a multimeter, which is truly pocket-sized and greatly facilitates on-site detection operations.

[0014] 3. Live-power detection. The present invention can directly detect the contact voltage drop of the air switch contact using an AC millivoltmeter and an active power meter. The contact resistance can be accurately detected by current calculation, so as to intuitively determine whether there is any abnormality in the switch operation condition, realize live-power detection, and greatly improve the on-site detection efficiency.

[0015] 4. Infrared temperature measurement inside the air switch. Many faults of air switches start from internal heating. However, air switches generally use plastic shells with low thermal conductivity. It is difficult to detect internal heating from the outside in time, and ordinary infrared thermal imagers cannot detect it. The present invention uses an innovatively designed infrared optical fiber and a detection snake to export the infrared image of the internal gap of the switch for detection by the infrared thermal imager, solving the problem that the internal heating of the switch cannot be measured by infrared temperature measurement.

[0016] 5. The simple method covers most of the inspection items of the air switch, completely avoiding the hidden danger of the switch running with a fault. The methods adopted by the present invention are all from cheap conventional electrical components, and the comprehensive inspection of the operation health of the air switch is realized at a very low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0018] Figure 1 This is a schematic diagram of an embodiment of a pocket-sized air switch characteristic detection device of the present invention.

[0019] Figure 2 It is a schematic diagram of the structure of an embodiment of a pocket-sized air switch characteristic detection device of the present invention. DETAILED DESCRIPTION

[0020] like Figure 1 As shown, it is a pocket-type air switch characteristic detection device of an embodiment of the present invention, comprising an AC millivoltmeter 1, a protective resistor 2, an active power meter 3, a clamp-type transformer 4, a metal snake 5, a spring contact 6, an infrared optical fiber 7, a germanium glass optical lens 8, and an electric signal timer 9; one signal input end of the AC millivoltmeter 1 is connected in series with the protective resistor 2 and then connected to a metal snake 5, and the other signal input end of the AC millivoltmeter 1 is connected to another metal snake 5; the voltage signal end of the active power meter 3 is connected in parallel with the two signal input ends of the AC millivoltmeter 1; the current signal end of the active power meter 3 is connected in series with the signal input end of the electric signal timer 9 and connected to the secondary winding of the clamp-type transformer 4. Two metal snakes 5 and the clamp-type transformer 4 are arranged on the same side of the housing of the pocket-type air switch characteristic detection device, and the heads of the two metal snakes 5 are provided with spring contacts 6, and the infrared optical fiber 7 is arranged in the middle of one of the metal snakes 5, one end of which is connected to the spring contact 6 and the other end is connected to the germanium glass optical lens 8. The power input terminals of the AC millivoltmeter 1, the active power meter 3 and the electric signal timer 9 are connected to the battery 10. The distribution structure of the components of the pocket-sized air switch characteristic detection device of this embodiment is as follows: Figure 2 shown.

[0021] The present invention firstly uses an AC millivoltmeter to detect the contact voltage drop between the switch contacts. The digital AC millivoltmeter has a large internal resistance and good anti-interference performance, and can accurately detect industrial frequency AC signals below 200mV. The present invention uses a series protective resistor 2 to effectively avoid meter damage caused by incorrect connection to high voltage, and realizes contact voltage drop measurement. A general air switch is provided with an electromagnetic tripping coil, which makes the contact voltage drop also include the inductance part. In order to accurately calculate the contact resistance of the contact, it is necessary to provide a current signal. The present invention uses an open mutual inductor 4 to detect the loop current. In this way, when used, the loop current is clamped while the contact voltage drop is measured. The contact resistance can be accurately calculated through the phase calculation of the active power meter 3. The contact resistance is the most characteristic quantity that can characterize the steady-state operation of the switch. The present invention uses the means of live detection to cleverly achieve this function. The voltage drop detection of the present invention also adopts a metal bellows, which can change its shape arbitrarily, so it only needs to be bent into an appropriate shape and then operated with one hand. With the help of the spring contact on the top of the bellows, the upper and lower wiring posts of the same phase of the switch are inserted one by one, so as to sensitively detect the contact voltage drop and contact resistance.

[0022] Secondly, the electric signal timer and mutual inductor are used to detect the tripping time and the synchronization of the three phases. As long as a larger load is added to the lower level of the tested switch, and then the switch is closed to supply power, the clamp-type mutual inductor of the present invention is used to detect the three-phase conductive circuit, and the electric signal timer will accumulate and calculate the time from the switch closing to the tripping, thereby calculating whether its tripping characteristics meet the load requirements. If the clamp-type mutual inductor of the present invention clamps the three phases at the same time, the timer cannot detect the tripping time of the switch because the magnetic field balance of the three-phase current is offset, but it can sensitively detect whether there is inconsistency in the three phases of the switch. If the three-phase switches are opened at the same time and the synchronization is good, the unbalanced current in the zero phase will exist for a very short time. If one phase moves slowly or the arc extinguishing ability is reduced, the unbalanced current will appear in the zero phase for a long time, so that the problem of three-phase inconsistency or reduced arc extinguishing ability can be intuitively and obviously detected by the electric signal timer, and the hidden danger of three-phase inconsistency that may exist in the switch is fundamentally discovered.

[0023] Finally, the infrared optical fiber inside the bellows is used to realize infrared temperature measurement inside the air switch. Many faults of air switches start from internal heating. However, air switches generally use plastic shells with low thermal conductivity, and internal heating is difficult to detect in time from the outside. General infrared thermal imagers cannot detect it. The present invention uses infrared optical fiber and, with the help of the detection bellows, the infrared image of the internal gap of the switch is exported to the germanium glass lens, which can be easily detected by the infrared thermal imager through the lens, solving the problem that the internal heating of the switch cannot be infrared temperature measured.

[0024] It should be noted that the above-mentioned embodiments are intended to illustrate the present invention rather than to limit the present invention. Many technical features in different embodiments of the present invention may be interchangeable or omitted, and the arrangements of many components may be changed as needed. The "one" or "a" before an element of the present invention does not exclude the presence of a plurality of such elements. These changes should all fall within the scope of protection of the present invention.

Claims

1. A pocket-sized air switch characteristic detection device, characterized in that: It includes an AC millivoltmeter (1), a protective resistor (2), an active power meter (3), a clamp-on transformer (4), a metal corrugated tube (5), and an electric signal timer (9); One signal input end of the AC millivoltmeter (1) is connected in series with the protective resistor (2) and then connected to one of the metal corrugated tubes (5); the other signal input end of the AC millivoltmeter (1) is directly connected to another of the metal corrugated tubes (5); the voltage signal end of the active power meter (3) is connected in parallel with the two signal input ends of the AC millivoltmeter (1); the current signal end of the active power meter (3) is connected in series with the signal input end of the electric signal timer (9) and connected to the secondary winding of the clamp-on transformer (4); The heads of the two metal snake skin tubes (5) are provided with spring contacts (6), which can be inserted into the upper and lower wiring posts of the same phase of the switch, and the clamp-type mutual inductor detects the loop current; The two metal snake tubes (5) have an axial infrared optical fiber (7) disposed at the center of one of the metal snake tubes (5); one end of the infrared optical fiber (7) is connected to a spring contact (6) and the other end is connected to a germanium glass optical lens (8).

2. The air switch characteristic detection device according to claim 1, characterized in that: The two metal corrugated tubes (5) and the clamp-on mutual inductor (4) are arranged on the same side of the housing of the pocket-sized air switch characteristic detection device.

3. The air switch characteristic detection device according to claim 2, characterized in that: The power input terminals of the AC millivoltmeter (1), the active power meter (3) and the electric signal timer (9) are connected to the battery (10).

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