① The type of molded case circuit breaker selected shall be determined according to the load nature, fault category and line protection requirements of low-voltage distribution system, and shall comply with the current relevant national standards.

②斷路器的額定電壓、額定頻率應與所在回路的標稱電壓及標稱頻率相適應。

② The rated voltage and rated frequency of the circuit breaker shall adapt to the nominal voltage and nominal frequency of the circuit.

③斷路器的額定電流不應小于所在回路的負載計算電流。

③ The rated current of the circuit breaker shall not be less than the load calculation current of the circuit.

④斷路器應適應所在場所的環境條件。

④ The circuit breaker shall adapt to the environmental conditions of the site.

⑤斷路器應滿足短路條件下的動穩定和熱穩定要求。用于斷開短路電流時，應滿足短路條件下的通斷能力。

⑤ The circuit breaker shall meet the requirements of dynamic stability and thermal stability under short circuit conditions. When used to disconnect short-circuit current, it shall meet the on-off capacity under short-circuit conditions.

低壓斷路器應根據不同故障類別和具體工程要求，選擇相適應的保護形式。其整定原則一般來說主要包括：

The low-voltage circuit breaker shall select appropriate protection forms according to different fault categories and specific engineering requirements. Generally speaking, the setting principles mainly include:

①斷路器在正常使用中和用電設備正常起動時，所裝設的保護不應動作。

① When the circuit breaker is in normal use and the electrical equipment is started normally, the installed protection shall not act.

②斷路器的最根本任務就是起到保護作用，必須在規定的時間內能有效地切斷故障電路，滿足規范最基本的要求。

② The most fundamental task of the circuit breaker is to play a protective role. It must be able to effectively cut off the fault circuit within the specified time to meet the most basic requirements of the specification.

③低壓配電系統各級斷路器的保護動作特性應能彼此協調配合，要有選擇性的動作，即發生故障時，應使靠近故障點的斷路器保護首先切斷，而其靠近電源側的上一級保護不應動作，盡可能地縮小斷電范圍。

③ The protection action characteristics of circuit breakers at all levels of low-voltage distribution system shall be able to coordinate with each other and act selectively, that is, in case of fault, the circuit breaker protection close to the fault point shall be cut off first, while the upper level protection close to the power supply side shall not act, so as to reduce the power-off range as much as possible.

在低壓配電系統中，主要設計任務就是合理地選擇保護電器，根據斷路器的整定原則要求，通過正確的整定其參數來實現各種保護功能，但這些整定原則又可能相互發生矛盾。

In the low-voltage distribution system, the main design task is to reasonably select the protection appliances. According to the setting principle requirements of the circuit breaker, various protection functions can be realized by correctly setting its parameters, but these setting principles may conflict with each other.

例如：斷路器額定電流或整定電流大小受到整定原則第①和第②項的限定，而保護動作時間的快慢又受到整定原則第②和第③項的制約，所以必須經過準確的計算和認真的校驗，協調相互之間的矛盾，實現對立的統一，以符合規范規定的動作特性、動作時間和有選擇性保護的有關要求。

For example, the rated current or setting current of the circuit breaker is limited by items ① and ② of the setting principle, and the speed of the protection action time is restricted by items ② and ③ of the setting principle. Therefore, it is necessary to coordinate the contradictions between them through accurate calculation and careful verification, so as to achieve the unity of opposites, so as to meet the action characteristics specified in the specification Relevant requirements for action time and selective protection.

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Thank you for reading. The source of this article is ABB molded case circuit breaker agent. For more contents and questions, please click: http://www.xzthjc.com We will continue to work hard to provide you with services. Thank you for your support!