How large current generators work

How large current generators work

Power Systems Many high-current electrical devices need to accurately measure the resistance of loops in preventive tests and hand-off tests. The circuit breaker is an important electrical equipment in the power system. The national standard GB763, GB50150 and the power industry standard DL/T596 make provisions for the measurement of the circuit breaker's conductive loop resistance: DC voltage drop method should be used to measure and the current should not be less than 100A.

The resistance of the conductive circuit of the large current generator circuit breaker depends mainly on the contact resistance between the dynamic and static contacts of the circuit breaker. The existence of the contact resistance increases the loss of the conductor during power-on, so that the temperature at the contact point increases. The value of the value directly affects the current-carrying capacity during normal operation, and affects the cutting-off capability of the short-circuit current to some extent. Therefore, the circuit breaker resistance per phase is an important data for circuit breaker installation, maintenance and quality acceptance.

There are many ways to measure the contact resistance. Japanese scholar Isao Minowa proposed using superconducting quantum devices to measure contact resistance. H.Archi proposed using electrolyzer method to measure contact resistance. Polish scholar Jerzy Kaczarek proposed using third harmonic method to measure contact resistance. These methods are generally conducted under laboratory conditions. The method used by the institute. In engineering, the four-terminal method is usually used to measure the contact resistance of actual contacts.

In the past, a DC dual-arm bridge was commonly used to measure the contact resistance of a circuit breaker. However, when using two-arm bridges to measure the circuit breaker's conducting loop resistance, it is difficult to eliminate the large-resistance oxide film because the two-arm bridge measurement loop passes a weak current, and the measured resistance value is too large. However, the oxide film is easily broken at a large current and does not prevent the normal current from passing through. Therefore, the test should not be too small when using the DC voltage drop test.

The high current generator measures the effect of the circuit breaker in the loop resistance.

Power Systems Many high-current electrical devices need to accurately measure the resistance of loops in preventive tests and hand-off tests. The circuit breaker is an important electrical equipment in the power system. The national standard GB763, GB50150 and the power industry standard DL/T596 make provisions for the measurement of the circuit breaker's conductive loop resistance: DC voltage drop method should be used to measure and the current should not be less than 100A. The resistance of the breaker circuit is mainly determined by the contact resistance between the dynamic and static contacts of the circuit breaker.

The existence of the contact resistance of the large current generator increases the loss of the conductor when it is energized, and increases the temperature at the contact point. The value of the value directly affects the current carrying capacity during normal operation, and affects the cutting-off capability of the short-circuit current to some extent. . Therefore, the circuit breaker resistance per phase is an important data for circuit breaker installation, maintenance and quality acceptance.

In the past, a DC dual-arm bridge was commonly used to measure the contact resistance of a circuit breaker. However, when using two-arm bridges to measure the circuit breaker's conducting loop resistance, it is difficult to eliminate the oxide film with a large resistance because the two-arm bridge measurement loop passes a weak current, and the measured resistance value is too large. However, the oxide film is easily broken at a large current and does not prevent the normal current from passing through. Therefore, the test should not be too small when using the DC voltage drop test.

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