CN203772963U - Super capacitor-based electrical equipment loop resistance test apparatus - Google Patents

Abstract

The utility model provides a circuit resistance testing device for electrical equipment based on a supercapacitor, which includes a charging circuit, a main discharge circuit, a voltage isolation sensor, and an industrial computer with a data acquisition card; the charging circuit includes a charger, a supercapacitor, and a charging protection resistor. ; The main discharge circuit includes supercapacitors, thyristors, shunts, and electrical equipment under test; the charger is connected to the supercapacitor, and the supercapacitor forms a series circuit with thyristors, shunts, and electrical equipment under test. The voltage isolation sensor is connected, and the voltage isolation sensor and the thyristor are respectively connected with the data acquisition card. The utility model utilizes the supercapacitor to generate the shock current of the thousand-ampere-level long-wave head, aiming at the circuit resistance presented by the conductive circuit nodes of various electrical equipment in the power system (GIS conductive circuit, high-voltage circuit breaker, high- and medium-voltage isolating switch, and high- and medium-voltage busbar, etc.) The difference, accurate measurement to get the loop resistance value of electrical equipment.

Description

Electrical equipment loop resistance test device based on supercapacitor

technical field

The utility model provides a circuit resistance testing device for electrical equipment based on a supercapacitor, which belongs to the technical field of circuit resistance detection. In view of the needs of performance testing of conductive loop nodes of various electrical equipment, the characteristics of the contact resistance of conductive loop nodes of various electrical equipment and the basic range of loop resistance measurement are integrated.

On the basis of electromagnetic interference and measurement accuracy, accurately measure the loop resistance of electrical equipment.

Background technique

The contact resistance of the conductive circuit node of electrical equipment is composed of the contact resistance between the contact of the conductive connector or various types of wire crimping joints and the conductor connection parts at both ends of it. Since the conductor resistance is much smaller than the contact resistance of the loop, the loop resistance is basically determined by the contact resistance. The scientific nature of the measurement principle of contact resistance will directly affect the accuracy of the measurement value.

There are many types of conductive loop nodes of electrical equipment, but the physical model of their contact resistance is the same, that is, the contact resistance is composed of shrinkage resistance and membrane resistance. Shrink resistance refers to the metal contact between the contacts of the conductive connector, which is characterized by point contact. Even if the external force closes it tightly, it is only the difference in the number of contact points. Since the contact is a point contact, the flow area becomes much smaller, resulting in a much larger resistance at the contact point. This resistance is called shrinkage resistance; film resistance refers to the oxidation of the air after the conductive connectors are separated, and other Affected by the factors, a layer of oxide film will be formed at the conductor contact, which will lead to the deterioration of the conductivity of the conductor. The existence of the oxide film will significantly increase the resistance. The resistance caused by this part of the reason is called film resistance. Contact resistance is mainly composed of film resistance and shrinkage resistance. The existence of contact resistance will increase the electrical loss of the contact part of the conductive connector, and the temperature of the contact will rise, causing the fault of the conductive connector and affecting the safe operation of the system.

Contact resistance belongs to the small resistance of micro-ohm level. The traditional methods of measuring micro-resistance include voltage drop method and micro-ohmmeter method. In engineering, the circuit resistance test of high-voltage and large-capacity conductive connectors usually adopts the DC voltage drop method of four-terminal wiring, and the current acts on the circuit, and the circuit resistance is obtained according to the voltage drop and the passing current measurement. The "Preventive Test Regulations for Electric Equipment" stipulates that the current of the DC voltage drop method shall not be less than 100A. The traditional loop resistance test uses a switching rectifier power supply, which is bulky and heavy, inconvenient to carry and has a single function. It has been reported in the literature that a rectangular pulse power supply is used, but it is only suitable for non-inductive circuits. There are also literatures that use capacitors and inductors to form a second-order oscillation circuit. The second-order oscillation circuit can eliminate the influence of inductance on the measurement results by sampling the signal near the current peak value, but the current peak value is only 100A, and the duration is short. For Elimination of the surface film of the contacts is disadvantageous.

The resistance value of the contact resistance of the conductive circuit node of electrical equipment is generally tens of micro-ohms to hundreds of micro-ohms, so to accurately measure the resistance value, a large current must be passed. The test current recommended by the country is 100A, but as recent research shows, there is a certain difference in the resistance of the loop resistance measured under a 100A DC power supply and a 300A DC power supply, and the loop resistance measured under a 300A current source Resistor values are more accurate. At the same time, many circuit breaker manufacturers have found that the measured value under 1000A current will better reflect the conduction state of the contacts. These studies have shown that accurate measurement of loop resistance must use a power supply that can output a larger current.

At present, most of the loop resistance measuring instruments at home and abroad use switching power supplies, which can only output a current of 100A to 300A. To generate a larger current, the cost and weight of the equipment will be greatly increased, which basically cannot meet the requirements of field testers. There are foreign literature reports that the electrolytic capacitor bank is used as the energy storage power source, which can release a current of 1kA, but the mass of the capacitor bank itself reaches 10kg, and the use and maintenance of the electrolytic capacitor is very difficult, which cannot meet the requirements of engineering applications.

The progress and development of science and technology make the connection between various disciplines more and more close, and the development of electrical equipment testing technology also depends on the development achievements of other disciplines. In recent years, an energy storage element called a supercapacitor has been widely used in important industrial fields, such as aerospace, cranes, electric vehicles, UPS power supplies, renewable energy and military fields. The supercapacitor is composed of surface porous activated carbon and organic electrolyte. The outer shell is sealed by argon arc welding and connected to the external environment through electrodes. Supercapacitors have excellent power characteristics. Compared with batteries of the same volume, they have more than 10 times the power density and more than 100 times the charge and discharge rate. The excellent characteristics of supercapacitors such as large capacitance, small internal resistance, high charge and discharge rate, high safety factor, simple charge and discharge circuit, and long-term maintenance-free use provide a solid foundation for the development of electrical equipment circuit resistance detection devices.

Utility model content

The utility model proposes a circuit resistance testing device for electrical equipment based on a supercapacitor. Apply supercapacitors to generate thousand-ampere-level long-wave head impulse currents, and aim at the differences in loop resistance presented by conductive loop nodes of various electrical equipment in the power system (GIS conductive loops, high-voltage circuit breakers, high- and medium-voltage disconnectors, and high- and medium-voltage busbars, etc.) , to get the loop resistance value of the electrical equipment.

A device for testing the circuit resistance of electrical equipment based on a supercapacitor, including a charging circuit, a main discharge circuit, a voltage isolation sensor, and an industrial computer with a data acquisition card; the charging circuit includes a charger, a supercapacitor, and a charging protection resistor; the main discharging circuit Including supercapacitors, thyristors, shunts, and electrical equipment under test; chargers are connected to supercapacitors, supercapacitors, thyristors, shunts, and electrical equipment under test form a series circuit, shunts, electrical equipment under test are respectively connected to voltage isolation sensors Connection, the voltage isolation sensor, the thyristor are respectively connected with the data acquisition card. the

The supercapacitor is charged by the charger, and the external signal triggers the thyristor to conduct, and the supercapacitor discharges the circuit. According to the relationship between the discharge characteristics of the supercapacitor and the circuit resistance, the impulse current of the long-wave head of the kiloampere level is guaranteed to be obtained;

Use the existing industrial computer to measure and collect data on the voltage at the end of the discharge circuit. During the discharge process, the voltage isolation sensor extracts the terminal voltage signals of the shunt and the electrical equipment under test respectively, and sends them to the industrial control after conversion by the high-speed data acquisition card. The industrial computer is responsible for the trigger discharge control of the supercapacitor, data acquisition, digital filtering and waveform interception, numerical calculation, storage and waveform display.

Compared with the prior art, a supercapacitor-based electrical equipment loop resistance testing device in the utility model can generate a kiloampere-level long-wave head inrush current, eliminate the influence of the measurement lead's own resistance and the contact resistance during connection, and Aiming at the differences in the loop resistance presented by the conductive loop nodes of various electrical equipment in the power system, accurately measure the loop resistance of electrical equipment.

Description of drawings

Fig. 1 is a schematic diagram of the test system of the present invention.

In the figure, 1—charger, 2—supercapacitor, 3—charging protection resistor, 4—thyristor, 5—shunt, 6—electrical equipment under test, 7—voltage isolation sensor.

Detailed ways

Fig. 1 is a schematic diagram of a test circuit of the present invention. Including charging circuit, main discharging circuit, voltage isolation sensor, industrial computer with data acquisition card; charging circuit includes charger, supercapacitor, charging protection resistor; main discharging circuit includes supercapacitor, thyristor, shunt, electrical equipment under test The charger is connected with the supercapacitor, and the supercapacitor forms a series circuit with the thyristor, the shunt, and the electrical equipment under test, and the shunt, the electrical equipment under test are respectively connected with the voltage isolation sensor, and the voltage isolation sensor and the thyristor are respectively connected with the data acquisition card. the

The supercapacitor is charged by the charger, and the external signal triggers the thyristor to conduct, and the supercapacitor discharges the circuit. According to the relationship between the discharge characteristics of the supercapacitor and the circuit resistance, the impulse current of the long-wave head of the kiloampere level is guaranteed to be obtained;

Use the existing industrial computer to measure and collect data on the voltage at the end of the discharge circuit. During the discharge process, the voltage isolation sensor extracts the terminal voltage signals of the shunt and the electrical equipment under test respectively, and sends them to the industrial control after conversion by the high-speed data acquisition card. The industrial computer is responsible for the trigger discharge control of the supercapacitor, data acquisition, digital filtering and waveform interception, numerical calculation, storage and waveform display.

The measurement of loop resistance is based on the discharge current source of the supercapacitor. When the fully charged supercapacitor discharges the measurement loop resistance during measurement, it will be able to generate a long-wave head impulse current up to a kiloampere level to meet the requirements for measuring the loop resistance of electrical equipment. . The supercapacitor has a large capacitance, which can reach tens or even hundreds of farads, and the general conductive connectors under test will show certain inductance characteristics, and the inductive components of the tested conductive connectors are small, so the main discharge circuit is non-conductive. oscillator circuit. When the current reaches the maximum, the rate of change of the loop impulse current is close to zero. At this time, the voltage drop signal of the loop is a pure resistance voltage drop. The size of this resistance will mainly reflect the contact status of the conductive rod contacts.

The capacitance of the supercapacitor can reach 83F, and the charging voltage is DC48V. Its maximum DC equivalent series resistance is 10mΩ, and its internal resistance is ultra-low; it can work continuously for 1,500 hours at a maximum operating temperature of 65°C, and the number of repeated charge and discharge can reach one million times.

The thousand-ampere-level long-wave head impulse current is obtained by using the characteristics of the large capacity of the supercapacitor and according to the selection of the supercapacitor, the product under test and the standard resistance to form an RLC circuit to obtain a non-oscillating circuit. The amplitude of the impulse current can reach the kiloampere level. The wave head time can reach about 10ms.

Claims (1)

1. the electrical equipment loop resistance proving installation based on ultracapacitor, is characterized in that: comprise charge circuit, main discharge circuit, voltage isolation sensor, with the industrial computer of data collecting card; Charge circuit comprises charger, ultracapacitor, charge protection resistance; Main discharge circuit comprises ultracapacitor, thyristor, shunt, tested electrical equipment; Charger is connected with ultracapacitor, ultracapacitor and thyristor, shunt, tested electrical equipment form series loop, shunt, tested electrical equipment are connected with voltage isolation sensor respectively, and voltage isolation sensor, thyristor are connected with data collecting card respectively.