DE112019006961T5 - METHOD OF EVALUATING OVERALL PERFORMANCE OF A DC HIGH SPEED SWITCH - Google Patents

Abstract

A method for evaluating the overall performance of a high-speed DC circuit breaker, comprising: an internal arcing resistance performance test used to determine whether the burn-out resistance of a tested circuit breaker meets requirements; an external isolation performance detection test used to determine whether the isolation limit of the tested circuit breaker meets requirements; a DC no-load current switching detection test used to determine whether the switching performance of the tested circuit breaker meets requirements; a mechanical performance test used to determine whether the mechanical reliability of the tested circuit breaker meets requirements; By means of four main detection tests including the internal arc resistance performance detection test, the external insulation performance detection test, the DC no-load current switching detection test and the mechanical power detection test, a comprehensive performance detection for the HSS can be performed in order to determine whether the performance requirements for a use are met, thereby ensuring the safety of the use.

Description

TECHNICAL AREA

The present invention relates to an evaluation method, and more particularly to a method for evaluating an overall performance of a DC high-speed switch.

BACKGROUND

High-speed DC switches (HSS) are mainly used in multi-ended flexible power transmission systems. The goal of the configuration of the DC high-speed switches is to realize the on-line switching on/off of a third station and the high-speed isolation of a DC line fault in the DC system, so that the reliability and availability of the whole DC system is improved.

1. (1) eine inhärente Langzeit-Überlastungsfähigkeit mit einer System-Nennübertragungskapazität von mehr als 1,05 pro Einheit (unter der maximalen Umgebungstemperatur);
2. (2) eine relativ starke Gleichstrom-Lichtbogenwiderstandsfähigkeit;
3. (3) eine Fähigkeit einen Leerlaufstrom einer Gleichstromleitung zu übertragen; und
4. (4) eine relativ hohe Öffnungsgeschwindigkeit, zuverlässige mechanische Aktionseigenschaften und keine Verweigerungsaktion oder Fehlaktion.

The DC high-speed circuit breaker is generally a type of open circuit breaker with hydraulic pressure or with a spring as the operating mechanism. In order to match with the multi-end system to realize the online on/off of the sending side and receiving side, there is a very high requirement of matching core performance parameters of the equipment, which mainly have the following characteristics:

1. (1) an inherent long-term overload capability with a system rated transmission capacity greater than 1.05 per unit (below the maximum ambient temperature);
2. (2) relatively strong DC arc resistance;
3. (3) an ability to carry no-load current of a DC line; and
4. (4) a relatively high opening speed, reliable mechanical action characteristics, and no refusal action or misaction.

1. 1. In einem geöffneten Zustand des HSS sind Konverterstationen auf beiden Seiten eines Schalters entriegelt; Gleichstromspannungen an beiden Seiten erreichen eine Nenngleichstromspannung und werden stabil; und der HSS kann zu diesem Zeitpunkt zuverlässig geschlossen werden.
2. 2. In einem geschlossenen Zustand des HSS ist die Konverterstation auf einer Seite eines Schalters gesperrt; eine Gleichstromspannung auf einer gesperrten Seite bleibt zu Beginn unverändert; und der HSS sollte in der Lage sein, zuverlässig zu schalten. Aufgrund der Entladung eines PT-Widerstands auf einer Polarleitung verringert sich auf der gesperrten Seite eine Spannung zur Masse schrittweise; und somit sollte der HSS in der Lage sein, der sich schrittweise erhöhenden End-zu-End-Spannung vor dem Öffnen einer unterstützenden Klinge des Hochgeschwindigkeitsschalters standzuhalten.

1. 3. Wenn die Gleichstromleitung ausfällt, verschiebt eine HSS-leistungsseitige Konverterstation schnell eine Phase und die HSS-lastseitige Konverterstation sperrt schnell; und vor der HSS-Schaltaktion muss sie einem großen unmittelbaren Strom mit einer Amplitude von einem Vielfachen von zehn kA für ungefähr 100 ms standhalten. Der HSS wird nach dem Stromabfall auf Null geöffnet.
2. 4. Für die kurzzeitige Widerstandsfähigkeit gegen interne Lichtbögen erfordert das flexible Gleichstromprojekt Wudongde beispielsweise die Widerstandsfähigkeit gegen interne Lichtbögen von 3125A für 400 ms und 5 mal; und das Verbundprojekt Yungui erfordert ein Widerstandsvermögen gegen interne Lichtbögen von 3786A für 400 ms und 5 mal, wobei der Isoliermantel nach fünf Lichtbögen nicht beschädigt sein sollte.
3. 5. Der HSS muss eine zuverlässige mechanische Leistung für Hochgeschwindigkeitsschließung und -öffnung haben. Beispielsweise erfordert das Wudongde-Projekt, dass die Schließzeit kleiner als 100 ms und die Öffnungszeit kleiner als 30 ms ist.
4. 6. Der HSS muss nicht die Fähigkeit aufweisen, Gleichstrom oder Fehlstrom zu unterbrechen. Allerdings muss der HSS die Fähigkeit aufweisen, den Residualstrom der Gleichstromleitung zu unterbrechen, der im Allgemeinen um 20 A liegt.

The DC high-speed switches mainly include four operating conditions, namely, stable closing, switching transition process, stable opening, and closing transition process. Under the four operating conditions encountered by the HSS, the following functions are required.

1. 1. In an open state of the HSS, converter stations on either side of a switch are unlocked; DC voltages on both sides reach a rated DC voltage and become stable; and the HSS can be reliably closed at that time.
2. 2. In a closed state of the HSS, the converter station is locked on one side of a switch; a DC voltage on a blocked side initially remains unchanged; and the HSS should be able to switch reliably. Due to the discharge of a PT resistor on a polar line, a voltage to ground gradually decreases on the blocked side; and thus the HSS should be able to withstand the incrementally increasing end-to-end stress before opening a supporting blade of the high-speed switch.

1. 3. When the DC line fails, an HSS power-side converter station quickly shifts a phase, and the HSS load-side converter station quickly locks; and prior to the HSS switching action, it must withstand a large instantaneous current of amplitude in multiples of tens of kA for approximately 100 ms. The HSS opens after the current drops to zero.
2. 4. For short-time internal arc resistance, Wudongde flexible DC project, for example, requires internal arc resistance of 3125A for 400ms and 5 times; and the Yungui joint project requires an internal arc resistance of 3786A for 400ms and 5 times, and the insulating jacket should not be damaged after five arcs.
3. 5. The HSS must have reliable mechanical performance for high speed closing and opening. For example, the Wudongde project requires the closing time to be less than 100ms and the opening time to be less than 30ms.
4. 6. The HSS does not need to have the ability to interrupt DC or fault current. However, the HSS must have the ability to interrupt the residual current of the DC line, which is generally around 20A.

Therefore, before deploying the HSS, it is necessary to test, assess and evaluate the entire core performance of it. However, there is no currently available relevant test and evaluation procedure.

SUMMARY

An object of the present invention is to overcome the above deficiencies in the prior art and to provide a method for evaluating a comprehensive performance of a DC high-speed switch, for comprehensively testing and evaluating the HSS before using the HSS and for evaluating whether its performance meets the requirements to provide.

In order to solve the above problem, the technical solutions of the present disclosure are as follows.

• einen Test zur Erfassung einer Widerstandsleistung gegen interne Lichtbögen, der verwendet wird, um zu erkennen, ob die Brandfestigkeit eines getesteten Leistungsschalters Anforderungen erfüllt;
• einen Test zur Erfassung einer externen Isolierungsfähigkeit, der verwendet wird, um zu ermitteln, ob die Isolierungsgrenze des getesteten Leistungsschalters Anforderungen erfüllt;
• einen Test zur Erfassung eines Gleichstrom-Leerlaufstrom-Schaltens, der verwendet wird, um zu ermitteln, ob die Schaltleistung des getesteten Leistungsschalters Anforderungen erfüllt;
• einen Test zur Erfassung einer mechanischen Leistung, der verwendet wird, um zu ermitteln, ob die mechanische Zuverlässigkeit des getesteten Leistungsschalters Anforderungen erfüllt,
• ein Ermitteln, dass die Leistungsevaluierung des getesteten Leistungsschalters fehlgeschlagen ist, wenn der Test zur Erfassung der Widerstandsleistung gegen interne Lichtbögen, der Test zur Erfassung der externen Isolationsfähigkeit, der Test zur Erfassung des Gleichstrom-Lehrlaufstrom-Schaltens und/oder der Test zur Erfassung der mechanischen Leistung nicht bestanden wurde; und
• ein Bewerten der umfassenden Leistung des getesteten Leistungsschalters, um eine Leistungsbewertung durchzuführen, wenn der Test zur Erfassung der Widerstandsleistung gegen interne Lichtbögen, der Test zur Erfassung der externen Isolierungsfähigkeit, der Test zur Erfassung des Gleichstrom-Leerlaufstrom-Schaltens und der Test zur Erfassung der mechanischen Leistung alle bestanden wurden.
• Im Vergleich zum Stand der Technik hat die folgende Erfindung folgende vorteilhafte Effekte.

A method for evaluating overall performance of a DC high-speed switch includes:

• an internal arcing resistance performance test used to determine whether the fire resistance of a tested circuit breaker meets requirements;
• an external isolation capability test used to determine whether the isolation limit of the tested circuit breaker meets requirements;
• a DC no-load current switching detection test used to determine whether the switching performance of the tested circuit breaker meets requirements;
• a mechanical performance test used to determine whether the mechanical reliability of the tested circuit breaker meets requirements,
• a determination that the performance evaluation of the circuit breaker under test has failed if the internal arcing withstand performance test, the external insulation capability test, the DC no-load current switching test and/or the mechanical mechanical test performance was not passed; and
• evaluating the overall performance of the circuit breaker under test to perform performance evaluation when the internal arcing resistance performance detection test, the external insulating capability detection test, the DC no-load current switching detection test and the mechanical detection test performance all passed.
• Compared to the prior art, the present invention has the following advantageous effects.

A comprehensive performance assessment for the HSS can be performed using four main detection tests including the internal arcing resistance performance test, the external insulation capability test, the DC no-load current switching test and the mechanical performance test. to determine whether the performance requirements for use are met and thereby ensure safety of use.

character list

• 1 Fig. 12 is a flowchart of a method for evaluating overall performance of a DC high-speed switch according to an embodiment of the present invention;
• 2 Fig. 12 is a schematic circuit diagram of a loop of an internal arcing resistance test of a DC high-speed circuit breaker;
• 3 Fig. 12 is a schematic diagram of a system for evaluating contact discharge conditions of an arc chute in a circuit breaker;
• 4 Figure 12 is a schematic diagram of an infrared monitor of the arc chute;
• 5 Fig. 12 is a schematic flow chart of a temperature rise evaluation; and
• 6 Figure 12 is a circuit diagram of a loop for testing DC no-load current switching of a DC high-speed switch.

DETAILED DESCRIPTION OF EMBODIMENTS

The contents of the present disclosure are described in detail below in conjunction with the accompanying drawings and specific embodiments.

• Unter Bezugnahme auf 1 umfasst ein Verfahren zum Evaluieren einer umfassenden Leistung eines Gleichstrom-Hochgeschwindigkeitsschalters gemäß dieser Ausführungsform hauptsächlich:
  • einen Test zur Erfassung einer Widerstandsleistung gegen interne Lichtbögen, der verwendet wird, um zu erkennen, ob die Brandfestigkeit eines getesteten Leistungsschalters Anforderungen erfüllt;
  • einen Test zur Erfassung einer externen Isolierungsfähigkeit, der verwendet wird, um zu ermitteln, ob die Isolierungsgrenze des getesteten Leistungsschalters die Anforderungen erfüllt;
  • einen Test zur Erfassung eines Gleichstrom-Leerlaufstrom-Schaltens, der verwendet wird, um zu ermitteln, ob die Schaltleistung des getesteten Leistungsschalters die Anforderungen erfüllt;
  • einen Test zur Erfassung einer mechanischen Leistung, der verwendet wird, um zu ermitteln, ob die mechanische Zuverlässigkeit des getesteten Leistungsschalters die Anforderungen erfüllt,
  • ein Ermitteln, dass die Leistungsevaluierung des getesteten Leistungsschalters fehlgeschlagen ist, wenn der Test zur Erfassung der Widerstandsleistung gegen interne Lichtbögen, der Test zur Erfassung der externen Isolationsfähigkeit, der Test zur Erfassung des Gleichstrom-Lehrlaufstrom-Schaltens und/oder der Test zur Erfassung der mechanischen Leistung nicht bestanden wurde; und
  • ein Evaluieren der umfassenden Leistung des getesteten Leistungsschalters, um eine Leistungsbewertung durchzuführen, wenn der Test zur Erfassung der Widerstandsleistung gegen interne Lichtbögen, der Test zur Erfassung der externen Isolierungsfähigkeit, der Test zur Erfassung des Gleichstrom-Leerlaufstrom-Schaltens und der Test zur Erfassung der mechanischen Leistung alle bestanden wurden.

Embodiments:

• With reference to 1 A method for evaluating a comprehensive performance of a DC high-speed switch according to this embodiment mainly includes:
  • an internal arcing resistance performance test used to determine whether the fire resistance of a tested circuit breaker meets requirements;
  • an external isolation capability test used to determine whether the isolation limit of the tested circuit breaker meets the requirements;
  • a DC no-load current switching detection test used to determine whether the switching performance of the tested circuit breaker meets the requirements;
  • a mechanical performance test used to determine whether the mechanical reliability of the tested circuit breaker meets the requirements,
  • a determination that the performance evaluation of the circuit breaker under test has failed if the internal arcing withstand performance test, the external insulation capability test, the DC no-load current switching test and/or the mechanical mechanical test performance was not passed; and
  • an evaluation of the comprehensive performance of the circuit breaker under test to perform a performance evaluation when the internal arcing resistance performance detection test, the external insulation capability detection test, the DC no-load current switching detection test and the mechanical detection test performance all passed.

Compared to the prior art, the present invention has the following advantageous effects.

A comprehensive performance measurement for the HSS can be performed using four main measurement tests including the internal arcing resistance performance test, the external insulation capability test, the no-load DC switching test and the mechanical performance test. to determine whether the performance requirements for use are met and thereby ensure safety of use.

Specifically, the internal arc resistance performance detection test mainly includes two steps, one for constructing a test loop and one for test operations.

Regarding 2 The test loop consists mainly of three loops, namely a short circuit loop 100, a rectifier loop 200 and an arc detection loop 300.

The short circuit loop 100 includes an auxiliary circuit breaker AB2, an alternator G and a short circuit transformer T. The short circuit current generator G, the short circuit auxiliary circuit breaker AB2 and a primary coil of the short circuit transformer T are connected in series to form the loop.

The rectifier loop 200 includes a first ammeter A1, a rectifier valve block V, a dry-type reactor L, a rectifier auxiliary circuit breaker AB1, and a current-limiting resistor R; the rectifier valve block V is connected to a second coil of the short-circuit transformer T and the first ammeter A1 is attached to a winding of the second coil of the short-circuit transformer T, which is connected to the rectifier valve block V; one end of the current-limiting resistor R is connected to an input end of the rectifier valve block V and another end is connected to one side of the rectifier auxiliary circuit breaker AB1; and one end of the reactor L is connected to an output end of the rectifier valve block V.

The arc monitoring loop 300 comprises a first voltmeter V1, a second voltmeter V2, a second ammeter A2 and a comprehensive characteristic parameter monitor 30; another end of the rectifier auxiliary circuit breaker AB1 is configured to be connected to a circuit breaker under test T0; and the comprehensive characteristic parameter monitor 30 is configured to monitor the circuit breaker under test T0 to obtain parameters required for a test; one end of the second ammeter A2 is connected to another end of the current-limiting resistor R and another end of the second ammeter A2 is connected to the circuit breaker under test T0 and are respectively grounded; one end of the first voltmeter V1 is connected to a line to which the second ammeter A1 and the circuit breaker under test T0 are connected, and another end is grounded; one end of the second voltmeter V2 is connected to a line to which the rectifier auxiliary circuit breaker AB1 and the circuit breaker under test T0 are connected, and another end is grounded.

Through the synergistic effects of the short-circuit loop, the rectifier loop and the arc monitor loop, an internal arc resistance test operation of the DC high-speed circuit breaker can be equivalently simulated. Through the equivalent simulated loops, the circuit breaker can be _{verified under the rated pressure of SF 6} in the circuit breaker for withstanding the discharge of a system load current during a fault or wrong decision in a system operating condition.

Among other things, the circuit breaker under test (e.g. the circuit breaker under test T0) in the test loop starts to open from the closed position and a DC _{arc I dc} flows through between the arcing contacts of the circuit breaker under test (the specific amplitude is based on a value that occurs in the most serious fault condition of a specific project, and is generally in the range of 3000 - 5000 A).

The time period is tac (the specific time period is based on a constant value of a protective off-time of a DC flexible valve in a specific project and is generally in the range of 300 to 500 ms).

A total of n arc resistance tests are performed and the specific number is determined based on the electrical resistance of the equipment required by the project.

In the initial state, the circuit breaker T0 under test is in the closed state and the auxiliary circuit breakers AB1 and AB2 are in the open state.

Parameter deviation requirements: the deviation of the DC current I _dc amplitude of the technical requirements is ± 10%, the time period may not exceed 0.5 s and the deviation from I _dc is ² t 0 - 10%.

• ein Überwachen von mechanischen Eigenschaften zum Erhalten einer Zeit-Kontakt-Geschwindigkeit und Zeit-Kontakt-Kurven, wenn der getestete Leistungsschalter T0 unterbrochen ist;
• eine Infrarotüberwachung zum Erhalten einer Änderungssituation eines Oberflächentemperaturanstiegs der Lichtbogenlöschkammer, die verursacht wird, wenn der getestete Leistungsschalter Wärmestrahlung während des Lichtbogens standhält; und
• ein Überwachen von Gaskomponenten zum Erhalten eines SF6-Gaskomponentenerzeugungsprozesses und -evolutionsprozesses, wenn der getestete Leistungsschalter einem internen Lichtbogen standhält.
• Insbesondere umfasst der Schritt der Testoperationen folgende Teilschritte.

In particular, the rectifier valve block V can be a bridge-type converter valve V composed of a controllable converter arm that can be set to 6 pulses or 12 pulses. The monitoring that the comprehensive characteristic parameter monitor is intended to perform on the circuit breaker under test includes:

• monitoring mechanical properties to obtain time-contact speed and time-contact curves when the circuit breaker T0 under test is open;
• an infrared monitor for obtaining a change situation of a surface temperature rise of the arc extinguishing chamber caused when the circuit breaker under test withstands heat radiation during arcing; and
• a monitoring of gas components to obtain a SF6 gas component generation process and evolution process when the circuit breaker under test withstands an internal arc.
• In particular, the test operations step includes the following sub-steps.

1) Configuration of parameters for the test loop

A transformation ratio of the short-circuit transformer is adapted to a required test current value and a rated voltage of a power generator; then a dry-type reactor is adjusted in the rectifier test loop so that a short-circuit current of DC _amplitude I dc can be generated on one side of the circuit breaker under test.

2) Generation of a short-circuit current

The circuit breaker under test is in a closed position before shorting the test loop. After the test starts, the auxiliary circuit breaker AB2 is closed to short-circuit the loop; the short circuit current is amplified along with a coil turns ratio through the shorting transformer T to generate the short circuit current required by the test; the short-circuit current is fed to the rectifier valve block of the rectifier loop; and a current amplitude is recorded by ammeter A1 in real time.

3) rectification

In the rectifier loop, the bridge type converter valve V composed of the controllable converter arm can be set to 6 pulses or 12 pulses; after the AC short-circuit current is rectified by the converter valve, the auxiliary circuit breaker AB1 is closed to output a DC current; and the direct current is adjusted by the dry-type reactor L and the current-limiting resistor R to produce a current amplitude I _dc that meets the test requirements.

4) Arc testing and condition monitoring

In the arc monitoring loop, the circuit breaker under test T0 is controlled to open after a rated DC current flows through the circuit breaker under test T0 to create a DC arc between arcing contacts along with a rapid relative opening movement of the contacts; after the contacts are opened in place, the DC arc can continue to discharge between the arcing contacts for a time tac required by the test; then, the auxiliary circuit breaker AB2 breaks the AC short-circuit loop to shut down a power supply on a power source side, so that the arcing of the arcing contacts of the circuit breaker T0 under test is gradually weakened and finally extinguished. At this point a test is complete. According to the test requirements, tests are performed n times. To prevent personal injury, the test interval should be based on the time required for the temperature of the circuit breaker under test to return to ambient temperature.

During the test, core parameters such as dynamic resistance, evolution of gas composition, opening and closing speed, and infrared temperature rise of the arc quenching chamber are recorded; and whether the tested circuit breaker's resistance to internal arcing meets the requirements is analyzed according to these parameters.

1. 1) Gültiger Kontaktzustand der Lichtbogenkontakte: während des Öffnungs- und Schließprozesses des Leistungsschalters wird angenommen, dass die Lichtbogenkontakte in dem gültigen Kontaktzustand sind, wenn der Kontaktwiderstand des Lichtbogenkontakts kleiner als oder gleich einem bestimmten Schwellenwert ist (der mit Bezug auf den gemessenen Wert des dynamischen Kontaktwiderstands angegeben sein kann); und es wird angenommen, dass die Lichtbogenkontakte einen ungültigen Zustand und in einen Trennungszustand (der keine absolute Trennung ist, aber zur Einfachheit der Datenanalyse) durchlaufen, wenn der Kontaktwiderstand größer als der Schwellenwert ist. Da der Teststrom über 2000 A während eines Testens des dynamischen Widerstands erreicht, können kurze Lichtbogenphänomene auftreten, wenn die Metalle der Lichtbogenkontakte absolut getrennt sind. Es ist ungenau, mit Hilfe von Tests eine Zeit als eine absolute Trennungszeit der Kontakte zu verwenden, wenn der Kontaktwiderstand unendlich groß ist. Deshalb definiert die vorliegende Erfindung einen bestimmten Schwellenwert als einen Kontaktrandwert der Lichtbogenkontakte lediglich für die Einfachheit der Trendanalyse der Testdaten.
2. 2) Gültige Kontaktverschiebung L (mm): während des Öffnungs- und Schließprozesses des Leistungsschalters wird eine entsprechende Kontaktverschiebung, die erhalten wird, wenn der Kontaktwiderstand der Lichtbogenkontakte kleiner als oder gleich dem Schwellenwert (2000 µΩ) ist, direkt nachdem ein Hauptkontakt getrennt wurde, als gültige Kontaktverschiebung bezeichnet.
3. 3) Kumulativer Kontaktwiderstand R_accu (µΩ * mm): der kumulative Kontaktwiderstand ist ein kumulativer Wert des Kontaktwiderstands zu der dem gültigen Kontaktverschiebung entsprechenden Abtastzeitpunkt. Die Abtastrate eines Testinstruments ist 20 k, d.h. ein entsprechender Kontaktwiderstandswert wird alle 0,05 ms erhalten. Der Kontaktwiderstand innerhalb des gültigen Kontaktverschiebungskurvenbereichs ist integriert, um den kumulativen Kontaktwiderstand (µΩ * mm) zu erhalten.
4. 4) Mittlerer Kontaktwiderstand R_ave (µΩ/mm): der mittlere Kontaktwiderstand (µΩ/mm) wird erhalten, indem der kumulative Kontaktwiderstand durch die gültige Kontaktverschiebung geteilt wird, und er kann die Änderungen des Kontaktwiderstands und der gültigen Kontaktverschiebung nach einer Kontaktentladung besser widerspiegeln.

In particular, the dynamic resistance includes 4 core property parameters, which are specifically defined as follows.

1. 1) Valid contact state of the arcing contacts: during the opening and closing process of the circuit breaker, the arcing contacts are considered to be in the valid contact state when the contact resistance of the arcing contact is less than or equal to a certain threshold value (which, with reference to the measured value of the dynamic contact resistance can be specified); and the arcing contacts are assumed to go through an invalid state and into a disconnection state (which is not absolute disconnection, but is for ease of data analysis) when the contact resistance is greater than the threshold. Since the test current reaches over 2000 A during dynamic resistance testing, brief arcing phenomena can occur when the metals of the arcing contacts are absolutely separated. It is inaccurate to use a time as an absolute separation time of the contacts by testing when the contact resistance is infinitely large. Therefore, the present invention defines a certain threshold as a contact edge value of the arcing contacts solely for the convenience of trending the test data.
2. 2) Valid contact displacement L (mm): during the opening and closing process of the circuit breaker, a corresponding contact displacement obtained when the contact resistance of the arcing contacts is less than or equal to the threshold value (2000 µΩ) immediately after a main contact is separated, referred to as a valid contact displacement.
3. 3) Cumulative contact resistance R _accu (µΩ * mm): the cumulative contact resistance is a cumulative value of the contact resistance at the sampling time corresponding to the valid contact displacement. The sampling rate of a test instrument is 20 k, ie a corresponding contact resistance value is obtained every 0.05 ms. The contact resistance within the valid contact displacement curve range is integrated to obtain the cumulative contact resistance (µΩ * mm).
4. 4) Average contact resistance R _ave (µΩ/mm): the average contact resistance (µΩ/mm) is obtained by dividing the cumulative contact resistance by the valid contact displacement, and it can better reflect the changes in contact resistance and valid contact displacement after a contact discharge .

Before and after the arcing test and during each test interval, the dynamic resistance of the arcing contacts of the circuit breaker is measured; the characteristic parameters of the arcing contact in the discharge state are recorded; the arcing resistance of the arcing contacts is evaluated, completing the records in the following table. test sequence 1 ^pc 2 ^nd 3 ^approx ...... n+1 ^th cumulant Prototype resistance arc amplitude (kA) (product under test) 0 Cumulative arc resistance energy ΣI ² *t _arc 0 Arc resistance (kA) * number of resistors 0 Valid contact displacement L (mm) Cumulative contact resistance R _accu (µΩ*mm) Mean contact resistance R _ave (µΩ/mm)

When the valid contact displacement L of the arcing contacts is in the range of 0 - 5 mm, the average contact resistance decreases rapidly as the valid contact displacement increases. After the contact displacement is greater than 5mm, the average contact resistance change is generally gradually stable.

Before and after the arc resistance test, the changes in the length and width of the arcing contacts should be recorded.

The tested prototype is disassembled to measure the switch dimensions and the component weights of the moving light contacts and the static light contacts. Weight change before and after the test (g) Static arcing contact Moving arcing contact Change in weight of moving and static arcing contacts Complete change of two switches Before the test After the test change value Before the test After the test change value prototype Switch A switch B Dimensional changes of the light contacts before and after the test (g) Static arcing contact Moving arcing contact Change value of the moving and static arcing contacts Before the test After the test change value Before the test After the test change value prototype length Switch A Switch B diameter Switch A Switch B

Among other things, a method for evaluating the discharge state of the contacts in the arc quenching chamber of the circuit breaker in 3 shown and includes the following steps.

1. 1) zu evaluierende Parameterinformationen des Leistungsschalters: eine Planungsnummer der Leistungsschalter, eine Phasendifferenz, ein Spannungslevel, ein Leistungsschaltermodell, ein Hersteller, eine Inbetriebnahmezeit;
2. 2) initiale charakteristische Parameter dieses Modells des Leistungsschalters:
   • eine gültige Kontaktverschiebung der Lichtbogenkontakte L (mm); ein kumulativer Kontaktwiderstand der Lichtbogenkontakte R_accu (µΩ * mm); ein mittlerer Kontaktwiderstand der Lichtbogenkontakte R_ave (µΩ/mm); und
3. 3) charakteristische Parameter des in einem aktuellen Zustand zu bewertenden Leistungsschalters: eine gültige Kontaktverschiebung L (mm) der Lichtbogenkontakte; eine kumulativer Kontaktwiderstand R_accu (µΩ * mm) der Lichtbogenkontakte; ein mittlerer Kontaktwiderstand R_ave (µΩ/mm) der Lichtbogenkontakte.

In the first step, a user extracts arc quenching chamber characteristic parameters of the circuit breaker by dynamic resistance testing technology and inputs them into an evaluation system. The input data includes:

1. 1) parameter information of the circuit breaker to be evaluated: a planning number of the circuit breakers, a phase difference, a voltage level, a circuit breaker model, a manufacturer, a commissioning time;
2. 2) initial characteristic parameters of this circuit breaker model:
   • a valid contact displacement of the arcing contacts L (mm); a cumulative contact resistance of the arcing contacts R _accu (µΩ * mm); an average contact resistance of the arcing contacts R _ave (µΩ/mm); and
3. 3) characteristic parameters of the circuit breaker to be evaluated in a current state: a valid contact displacement L (mm) of the arcing contacts; a cumulative contact resistance R _accu (µΩ * mm) of the arcing contacts; an average contact resistance R _ave (µΩ/mm) of the arcing contacts.

In the second step: based on the database (a cumulative energy discharge fingerprint database; a contact characteristic parameter correlation database; an expert database for contact discharge states) a comprehensive evaluation of the characteristic parameters of the circuit breaker to be evaluated is carried out in an initial and current state, which is defined in the first step to be entered; and quantitative difference values of cumulative and opening-closing energy and a quantity correlation characteristic curve corresponding to the current discharge state of the arcing contacts are obtained.

In the third step, based on the results of the comprehensive analysis in the second step, the characteristic parameters are calculated; and determining the interval of a ratio of the valid contact displacement of the arcing contacts of the circuit breaker to the initial valid contact displacement.

In the fourth step, the current state of the arc quenching chamber of the circuit breaker is evaluated. If the ratio of the valid contact displacement of the arcing contacts to the initial valid contact displacement is within the range of 80 - 100%, a normal discharge condition is declared; when the ratio is within the range of 60 - 80%, a slight discharge state is indicated; when the ratio is within the range of 40 - 60%, an intermediate discharge state is indicated; when the ratio is within the range of 20 - 40%, a severe discharge state is indicated; and if the ratio is within the range of <20%, an abnormal condition is indicated.

During the circuit breaker internal arc test, the generation, growth and other development trends of various characteristic components of the SF ₆ gas in the arc quenching chamber are recorded. This data can serve as an important maintenance basis for the operation of this circuit breaker model and also as an important indicator for evaluating circuit breaker switching discharge.

A conventional speed sensor can be used for monitoring the opening and closing speed of the circuit breaker under test and is attached to a crank arm of an operating mechanism of the circuit breaker. When the circuit breaker T0 under test opens and closes, the opening and closing speed V, time t and action path I for characteristic parameters are transmitted in real time to the comprehensive monitoring device for comprehensive processing.

During the internal arc resistance test of the tested circuit breaker T0, the arcing contacts are continuously discharged by the arc t _arc and the temperature rise of the arc thermally radiates through an insulating gas to the insulating jacket of the arc quenching chamber, causing the surface of the arc quenching chamber to experience a temperature rise change of learns several K. Therefore, an infrared monitor based on an infrared radiation temperature measurement technique monitors the temperature rise change of the insulating jacket of the arc quenching chamber of the circuit breaker in real time, and transmits data to the comprehensive characteristic parameter monitor for comprehensive analysis and evaluation. In a type test, the temperature rise test data will be an important basis for post-operational condition assessment.

The circuit breaker is used as in particular in 4 shown with two arc chutes and provided with six temperature measurement points for each chute, namely left, middle and right points on each of the bottom and top layers.

After a temperature measurement, the temperature rise data (K) is recorded as follows: Temperature measurement pages Upper layer (temperature rise T2 K) Lower layer (temperature rise T2 K) Average value T1 Left center Right Left center Right arc quenching chamber 1 arc quenching chamber 2

1. 1. Während des Lichtbogenwiderstandsfähigkeitstests unterliegt die Temperatur des Isoliermantels jeder Lichtbogenlöschkammer einer Infrarotüberwachung; der Temperaturanstiegstest wird gemäß dem Grundsatz durchgeführt, bei dem linke, mittlere und rechte Punkte an jeder der oberen und unteren Schichten angeordnet sind, wobei der Temperaturanstieg an jedem Punkt als T2 aufgezeichnet wird; die Temperaturanstiege der zerstreuten Punkte in der Lichtbogenlöschkammer unterliegen einem Variantwurzelprozess, um einen mittleren Wert T1 zu erhalten.
2. 2. Es wird ermittelt, ob der Temperaturanstieg der lokal überhitzten Lichtbogenlöschräume den mittleren Wert T1 max überschreitet. Falls nein, ist ein normales Evaluierungsergebnis gegeben, und falls ja, wird die nächste Bewertung durchgeführt.
3. 3. Gemäß dem Temperaturanstieg eines stromführenden Leiters unter der normalen Lichtbogenwiderstandsfähigkeit, wird der Temperaturanstieg des Isoliermantels umgekehrt berechnet, um den berechneten Temperaturanstieg des stromführenden Leiters zu erhalten.
4. 4. Es wird ermittelt, ob die Testwerte der verstreuten Punkte auf dem Mantel der Lichtbogenlöschkammern einen ersten Grenzwert T2 max1 überschreiten. Falls ja, wird bewertet, dass der stromführende Leiter der Lichtbogenlöschkammer einen abnormalen Kontakt erfährt; und falls nein, wird die nächste Bewertung durchgeführt.
5. 5. Es wird ermittelt, ob die Testwerte der verstreuten Punkte auf dem Mantel der Lichtbogenlöschkammern einen ersten Grenzwert T2 max2 überschreiten. Falls ja, wird ermittelt, dass der stromführende Leiter der Lichtbogenlöschkammer einen Achtungswert erreicht und dass andere Hilfsbewertungsmittel angepasst werden sollten; und falls nein, wird die Temperaturanstiegsbewertung beendet. Gemäß den durch den Test geforderten Werten werden n-mal Tests zur Widerstandsfähigkeit gegen interne Lichtbögen durchgeführt. Während dem Test sollte der getestete Leistungsschalter T0 keine signifikanten externen Effekte zeigen, d.h. das getestete Objekt sollte nicht explodieren; und keine Löcher oder Risse, die andeuten, dass die Anforderungen zur Widerstandsfähigkeit gegen interne Lichtbögen erfüllt sind, sollten am Gehäuse erzeugt werden.

A temperature rise judgment procedure is in 5 shown and includes the following:

1. 1. During the arc resistance test, the temperature of the insulating jacket of each arc chute is subject to infrared monitoring; the temperature rise test is conducted according to the principle that left, middle and right points are arranged on each of the upper and lower layers, and the temperature rise at each point is recorded as T2; the temperature rises of the diffused points in the arc quenching chamber undergo a variant root process to obtain an average value T1.
2. 2. It is determined whether the temperature rise in the locally overheated arc quenching chambers exceeds the mean value T1 max. If no, a normal evaluation result is given, and if yes, the next evaluation is performed.
3. 3. According to the temperature rise of a live conductor under the normal arc resistance, the temperature rise of the insulating sheath is calculated inversely to obtain the calculated temperature rise of the live conductor.
4. 4. It is determined whether the test values of the scattered points on the shell of the arc chutes exceed a first limit value T2 max1. If yes, it is judged that the current-carrying conductor of the arc-extinguishing chute experiences an abnormal contact; and if no, the next evaluation is performed.
5. 5. It is determined whether the test values of the scattered points on the shell of the arc chutes exceed a first limit value T2 max2. If so, it is determined that the current-carrying conductor of the arc chute is reaching a caution level and that other auxiliary means of assessment should be adjusted; and if no, the temperature rise judgment is ended. Internal arcing resistance tests are performed n times according to the values required by the test. During the test, the tested circuit breaker T0 should not have any significant external no effects, ie the tested object should not explode; and no holes or tears indicating that internal arc resistance requirements are met should be created on the housing.

The mechanical reliability can be verified in the following way.

Due to the peculiarity of the position in the DC system, the HSS must have extremely high mechanical reliability and must not have mechanical defects such as refusal behavior, misbehavior and jamming during operation. After completing 10,000 mechanical closing and opening operations of a normal M2 mechanical performance level according to a standard, a mechanical limit condition test should be added. Mechanical reliability verification at limit speeds is presented below for a circuit breaker with a spring operated mechanism and with a hydraulic mechanism (including a hydraulic disc spring), respectively. After completing the operations under the test conditions in the table below, the circuit breaker has no failures such as refusal behavior, failure behavior and jamming, and the hydraulic mechanism has no oil leakage, frequent pressurization and impossible pressurization, and the test is passed.

1. Circuit breaker with spring operated mechanism

In the field of switching and turn-on speed of supply devices, mechanical operating performance of the devices under a maximum switching and turn-on speed and a minimum switching and turn-on speed are verified (not less than 500 times each). No abnormal behavior should occur during the test. After the test, the tested object should be checked for any abnormal damage. test condition Closing and opening speed requirement Highest closing speed + lowest opening speed Highest closing speed + Highest opening speed Lowest closing speed + Lowest opening speed Lowest closing speed + Highest opening speed Quantity No less than 500 No less than 500 No less than 500 No less than 500

2. Circuit breaker with hydraulic mechanism (including hydraulic disc spring)

In mechanical operations at limit opening and closing speeds and under a rated oil pressure, a throttle valve of the hydraulic mechanism is adjusted so that the opening speed and closing speed reach upper and lower limits, respectively. After the combination, a mechanical speed limit process is performed to verify the reliability of the mechanical process. Ranges of variation in opening and closing speeds should be recorded and compared before and after the test. test condition Requirement for closing and opening speed under a nominal oil pressure m/s Highest closing speed + lowest opening speed (3.8+7.7) Highest closing speed + Highest opening speed (3.8+8.5) Lowest closing speed + Lowest opening speed (3.2+7.7) Lowest closing speed + Highest opening speed (3.2+8.5) Quantity No less than 500 No less than 500 No less than 500 No less than 500

The DC no-load current switching detection test mainly includes two steps, namely a step of constructing a test loop and a step of performing test operations on the test loop.

As in 6 shown, the test loop comprises a first auxiliary power switch AB1, a second auxiliary power switch AB2, a capacitor bank C, a resistor R, an ammeter A, a first voltmeter V1, a second voltmeter V2 and a direct current high-voltage generator DC.

The DC high voltage generator CC, the second auxiliary power switch AB2 and the capacitor bank C are connected in series to form a loop. The capacitor bank C, resistor R and the second voltmeter V2 are connected in series to form a loop. One end of the first auxiliary circuit breaker AB1 is connected to the resistor R and another end is connected to one end of the circuit breaker under test T0. One end of the first voltmeter V1 is connected to a line between the first auxiliary circuit breaker AB1 and the circuit breaker under test T0 and another end is connected to a line to which the second voltmeter V2 and the capacitor bank C are connected. One end of the ammeter A is connected to the other end of the tested circuit breaker T0 and another end of the ammeter A is grounded and connected to a line to which the second voltmeter V2 and the capacitor bank C are connected.

In an initial state, the first auxiliary circuit breaker AB1 and the second auxiliary circuit breaker AB2 are in an open state, the circuit breaker T0 under test is in a closed state, and the direct current high voltage generator DC can generate a direct current high voltage for the capacitor C to a certain value output.

In particular, when testing the DC high-speed switch loop for testing DC no-load current switching, the following steps are included.

1) Configuration of parameters for the test loop

The resistance R=U/I is obtained according to a switching DC current I and a recovery voltage U of a test object.

The capacitor bank is configured, and a capacitance C of the capacitor bank and an internal resistance Rc of the capacitor bank are mainly determined. After the capacitor bank is charged, a DC loop is formed using a pre-charged capacitor bank and a resistive load; therefore the capacitor parameters can be obtained according to the following formula: $$I=\left(u+I{R}_C\right)\omega C.$$

wobei Ln ein Logarithmus einer natürlichen Konstante ist.The auxiliary circuit breakers AB2 and the auxiliary circuit breakers AB1 coordinate in an operation interval T1, the auxiliary circuit breaker AB1 and the tested circuit breaker T0 coordinate in an operation interval T2, which is required so that the time t is not exceeded when the current falls to I after the Test loop has been switched on, and otherwise a current for switching the circuit breaker under test is less than the required value I, which is determined in particular by a total time constant and can be obtained in particular from the following formula: $$\text{t}=RCL\text{n}\left(\frac{u+I{R}_C}{I{R}_C}\right),$$

where Ln is a logarithm of a natural constant.

The ranges of the ammeter A and the voltage levels of the voltmeters V1 and V2 must be greater than a required test value.

2) Energy storage for the capacitor bank

Auxiliary power switch AB2 is closed, capacitor bank is charged by DC high voltage generator DC for energy storage, and auxiliary power switch AB2 is open after energy storage reaches a value above U+IRc.

3) Discharge of the capacitor bank

The auxiliary circuit breaker AB1 is closed after a delay of the operation interval T1, the test loop is turned on, the current of the loop falls to some extent under the influence of an RC circuit and before falling to the test current I, the tested circuit breaker becomes T0 after a delay of the operation interval T2.

4) DC power interruption

When opening the tested circuit breaker T0, a DC arc is generated at a switch break, the DC arc corresponding to a dynamic resistance; in the course of the opening operation, a distance between moving and static arcing contacts is gradually increased, the resistance of the DC arc is gradually increased, a voltage at both ends of the switch is gradually increased, and the current of the loop is gradually reduced. When the current is reduced to a certain extent, the arc is extinguished because it is difficult to keep the arc burning. The arcing time T3 is recorded at this time. A product of the arcing time T3 and an average switching speed v of the circuit breaker must be smaller than a design opening distance L of the contacts, otherwise the opening movement stops and it is impossible to extinguish the DC arc, resulting in switching failure.

5) test criterion

The loop is switched on by a loop auxiliary switch when an initial state of the circuit breaker under test is in a closed position, then the circuit breaker under test T0 is opened at a flow time T2 and the test current I is normally interrupted through the circuit breaker under test after the arcing time T3, so that the arcing contact withstands the recovery voltage U without severe failure.

Ten tests each are performed for positive and negative polarities.

An interruption of the DC no-load current with positive and negative polarity is completed a certain number m times by the circuit breaker under test and it is determined that the test is successful.

In the external insulation performance detection test, testing and determination can be carried out by designing a dry arcing distance and a creepage distance of the external insulation of the circuit breaker, and the insulation performance of the external insulation under moisture, pollution or salt spray and other climatic conditions.

The above embodiments are only intended to illustrate the technical concept and features of the present invention and to enable those skilled in the art to understand and apply the content of the present disclosure accordingly, without limiting the scope of the present invention. Any equivalent changes or modifications made in accordance with the gist of the present invention should be construed as falling within the scope of the present invention.

Claims (6)

A method for evaluating an overall performance of a DC high-speed circuit breaker, comprising: an internal arcing resistance performance test used to determine whether a fire resistance of a tested circuit breaker meets requirements; an external isolation performance detection test used to determine whether an isolation limit of the tested circuit breaker meets requirements; a DC no-load current switching detection test used to determine whether a switching performance of the tested circuit breaker meets requirements; a mechanical performance test used to determine whether a mechanical reliability of the tested circuit breaker meets requirements; determining that a performance evaluation of the circuit breaker under test failed if the internal arc resistance performance test, the external insulation performance test, the DC no-load current switching test and/or the mechanical performance test have not been passed; and evaluating an overall performance of the circuit breaker under test to perform a performance evaluation when the internal arc resistance performance detection test, the external insulation performance detection test, the DC no-load current switching detection test, and the mechanical performance detection test all passed. procedure after claim 1 , wherein the test for detecting an internal arc resistance performance comprises: a step of constructing a test loop, the test loop comprising a short-circuit loop, a rectifier loop and an arc monitor loop, the short-circuit loop comprising a short-circuit auxiliary circuit breaker, an AC power source and a short-circuit transformer; the AC source, the short-circuit auxiliary circuit breaker and a primary coil of the short-circuit transformer are connected in series to form the loop; the rectifier loop comprises a first ammeter, a rectifier valve block, a reactor, a rectifier auxiliary circuit breaker and a current-limiting resistor; the rectifier valve block is connected to a secondary coil of the squirrel cage transformer and the first ammeter is attached to a winding of the secondary coil of the squirrel cage transformer that is connected to the rectifier valve block; one end of the current-limiting resistor is connected to an input end of the rectifier valve block, and another end is connected to an end of the rectifier auxiliary circuit breaker; and one end of the reactor is connected to an outlet end of the rectifier valve block; the arc monitoring loop comprises a first voltmeter, a second voltmeter, a second ammeter and a comprehensive characteristic parameter monitor; another end of the rectifier auxiliary circuit breaker is configured to be connected to a circuit breaker under test; and the comprehensive characteristic parameter monitor is configured to monitor the circuit breaker under test to obtain parameters required for a test; one end of the second ammeter is connected to another end of the current limiting resistor and another end of the second ammeter is connected to the circuit breaker under test and grounded; one end of the first voltmeter is connected to a line in which the second ammeter and the circuit breaker under test are connected and another end is grounded; one end of the second voltmeter is connected to a line to which the rectifier auxiliary circuit breaker and the circuit breaker under test are connected and another end is grounded; a step of test operations, comprising: a sub-step for configuring parameters for the test loop, comprising: adjusting a transformation ratio of the short-circuit transformer according to a required value of a test current and a rated voltage of a power generator, and then adjusting a dry-type reactor in the rectifier test loop so that a short-circuit current a direct current _amplitude I dc can be generated on one side of the circuit breaker under test; a sub-step of generating the short-circuit current, comprising: placing the circuit breaker under test in a closed position before short-circuiting the test loop; closing the shorting auxiliary circuit breaker to short the loop after the test begins; amplifying the short circuit current along with a coil turns ratio through the short circuit transformer to produce the short circuit current required by the test; inputting the short-circuit current to the rectifier valve block of the rectifier loop; and recording a real-time current amplitude through the first ammeter; a rectifying sub-step comprising: closing the rectifier auxiliary circuit breaker after the AC short-circuit current is rectified by a converter valve to output a DC current; and adjusting the direct current through the dry-type reactor and the current-limiting resistor to produce a current amplitude I _dc that meets the test requirements; a sub-step for performing arcing tests and condition monitoring, comprising: controlling the circuit breaker under test in the arcing monitoring loop to open after a nominal DC current flows through the circuit breaker under test to create a DC arc between arcing contacts together with a rapid relative opening movement of the contacts ; allowing the DC arc to continue to discharge between the arcing contacts for a period of time tac required by the test after the contacts are on be opened in their place; an interruption of the AC short-circuit loop by the short-circuit auxiliary circuit breaker to cut off a power supply on a power source side, so that the arcing of the arcing contacts of the tested circuit breaker T0 is gradually weakened and finally extinguished, one test is finished at this time and n times tests performed according to the test requirements, wherein a test interval is based on a time required for a temperature of the circuit breaker under test to return to an ambient temperature; during the test, dynamic resistance, gas composition evolution, opening and closing speed and infrared temperature rise of an arc quenching chamber for the tested circuit breaker are recorded; and n is a positive integer. procedure after claim 2 wherein the arcing monitor loop further comprises the comprehensive characteristic parameter monitor configured to monitor the circuit breaker under test to obtain the parameters required for the test. procedure after claim 3 wherein monitoring that the comprehensive characteristic parameter monitor is configured to target the circuit breaker under test comprises: monitoring mechanical properties to obtain time-contact velocity and time-contact curves when the tested Circuit breaker T0 switches; an infrared monitor for obtaining a change situation of a surface temperature rise of the arc extinguishing chamber caused when the circuit breaker under test is exposed to thermal radiation by arcs; and monitoring a gas composition to obtain an SF6 gas component generation and evolution process when the circuit breaker under test is exposed to internal arcing. procedure after claim 1 , wherein the test for detecting DC no-load current switching comprises: a step of constructing a test loop, the test loop having a first auxiliary power switch, a second auxiliary power switch, a capacitor bank, a resistor, an ammeter, a first voltmeter, a second voltmeter, and a A DC high voltage generator comprising, wherein the DC high voltage generator, the second auxiliary circuit breaker and the capacitor bank are connected in series to form a loop; the capacitor bank, resistor and second voltmeter are connected in series to form a loop; one end of the first auxiliary circuit breaker is connected to the resistor and another end is connected to one end of the circuit breaker under test; one end of the first voltmeter is connected to a line between the first auxiliary circuit breaker and the tested auxiliary circuit breaker and another end is connected to a line to which the second voltmeter and the capacitor bank are connected; one end of the ammeter is connected to another end of the circuit breaker under test and another end of the ammeter is grounded and connected to a line to which the second voltmeter and the capacitor bank are connected; a step of test operations, comprising: a sub-step for configuring parameters for the test loop, comprising: obtaining the resistance R=U/I corresponding to a switching direct current I and a recovery voltage U of a test object; configuring the capacitor bank and mainly determining a capacitance C of the capacitor bank and an internal resistance Rc of the capacitor bank, the second auxiliary circuit breaker and the first auxiliary circuit breaker coordinating in an operation interval T1, the second auxiliary circuit breaker and the tested circuit breaker coordinating in an operation interval T2, what is required so that the time T is not exceeded when the current falls to I after the test loop is switched on and otherwise a current for switching the circuit breaker under test is smaller than the required value I; and ranges of the ammeter and voltage levels of the first voltmeter and the second voltmeter must be higher than a required test value; an energy storage substep for the capacitor bank, comprising: closing the second auxiliary power switch, charging the energy storage capacitor bank by the DC high voltage generator, and opening the second auxiliary power switch after it reaches a value above U+IRc; a sub-step for discharging the capacitor bank, comprising: closing the first auxiliary circuit breaker after a delay of the operation interval T1, turning on the test loop, allowing the current of the loop to fall, and opening the circuit breaker under test after a delay of the operation interval T2 before drop to the test current I; a sub-step of interrupting a direct current, comprising: creating a direct current arc at a breaker break upon opening of the circuit breaker under test, the direct current arc being equivalent to a dynamic resistance; in the course of the opening operation, gradually increasing a distance between movable and static arcing contacts, gradually increasing a resistance of the DC arc, gradually increasing a voltage at both ends of the switch, and gradually reducing the current of the loop; when the current is reduced to some extent, extinguishing the arc because it is hard to keep burning the arc, and recording the arc time T3 at that time; and a requirement that a product of the arcing time T3 and an average switching speed v of the tested circuit breaker is smaller than a design opening distance L of the contacts of the tested circuit breaker, and otherwise the opening movement stops and it is impossible to extinguish the DC arc, resulting in a failure of the switching leads; and a sub-step of a test criterion comprising: turning on the loop by a loop auxiliary switch when an initial state of the circuit breaker under test is in a closed position, then opening the circuit breaker under test at flow time T2 and normally interrupting the test current I through the tested one circuit breaker after the arcing time T3, so that the arcing contact withstands the recovery voltage without severe failure; and the circuit breaker under test undergoing a specified number m of interruptions of open circuit DC current with positive and negative polarities and determining that the test is successful; where m is a positive integer. procedure after claim 5 , where the time t is calculated by the following formula: $$\text{t}=RCL\text{n}\left(\frac{u+I{R}_C}{I{R}_C}\right),$$

where Ln is a logarithm of a natural constant.

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