IEC 60077-4:2019标准是铁路应用中电气设备的重要标准之一，主要针对机车车辆中的电气元件，特别是交流断路器的规则。交流断路器是机车车辆中的重要电气元件，用于保护电路和设备，防止电路过载和短路等故障。因此，交流断路器的安全性和可靠性对于机车车辆的正常运行至关重要。

IEC 60077-4:2019标准规定了交流断路器的技术要求、试验方法、标记和包装等方面的内容。其中，技术要求包括断路器的额定电压、额定电流、额定短路开断电流、额定短路关合电流、额定频率、机械寿命、电气寿命、环境条件等。试验方法包括断路器的外观检查、机械性能试验、电气性能试验、环境试验等。标记和包装方面则规定了断路器的标记内容和包装要求。

IEC 60077-4:2019标准的实施可以有效提高交流断路器的安全性和可靠性，保障机车车辆的正常运行。同时，该标准的实施也有助于促进国际铁路应用中电气设备的标准化和统一。

相关标准
- IEC 60077-1:2017 Railway applications - Electric equipment for rolling stock - Part 1: General service conditions and general rules
- IEC 60077-2:2017 Railway applications - Electric equipment for rolling stock - Part 2: Electrotechnical components - General rules
- IEC 60077-3:2018 Railway applications - Electric equipment for rolling stock - Part 3: Electrotechnical components - Rules for electronic power converters
- IEC 60077-5:2018 Railway applications - Electric equipment for rolling stock - Part 5: Electrotechnical components - Requirements for electronic power converters used for driving electric traction motors
- IEC 60077-6:2018 Railway applications - Electric equipment for rolling stock - Part 6: Electrotechnical components - Rules for power electronic converters