APM521網絡電力儀表（以下簡稱儀表）按IEC國際標準設計，具有全電量測量、電能統計、電能質量分析事件記錄功能及網絡通訊等功能，主要用于電網供電質量的綜合監控。該系列儀表配有功能豐富的DI/DO模塊、AO模塊，可以靈活實現電氣回路全電量測量及開關狀態監控。

The APM521 network power meter (hereinafter referred to as the meter) is designed according to IEC international standards, featuring full electrical quantity measurement, energy statistics, power quality analysis, event logging functions, and network communication capabilities. It is primarily used for comprehensive monitoring of power supply quality in power grids. This series of meters is equipped with DI/DO modules and AO modules that offer a wealth of functions, allowing for flexible implementation of full electrical quantity measurement and monitoring of switch statuses in electrical circuits.

多功能性：支持四象限電能、諧波分析、需量統計、事件記錄等，滿足多樣化電力監測需求。

精度高：電壓、電流測量誤差±0.2%，電能計量符合D級標準，確保數據準確性。

靈活安裝：提供嵌入式、導軌式等多種安裝方式，適配不同場景需求。

安全可靠：通過UL、CE等認證，符合CATⅢ/CATⅡ安全標準，具備過載保護和雙重絕緣設計。

通信便捷：支持Modbus-RTU、DL/T 645-2007等多種協議，兼容RS485和以太網通信，便于系統集成。

擴展性強：可選配DI/DO模塊、AO模塊，實現開關狀態監控和模擬量輸出，滿足定制化需求。適用于工業、商業及電力系統，提供準確的電力監控解決方案。

Versatility: Supports four-quadrant energy measurement, harmonic analysis, demand statistics, event recording, and more, meeting diverse power monitoring needs.

High Accuracy:  Voltage and current measurement error within ±0.2%, with energy measurement complying with Class D standards, ensuring data accuracy.

Flexible Installation: Offers multiple installation methods, including embedded and DIN rail mounting, to adapt to different application scenarios.

Safety and Reliability: Certified by UL, CE, and others, compliant with CAT III/CAT II safety standards, featuring overload protection and double insulation design.

Convenient Communication:  Supports multiple protocols such as Modbus-RTU and DL/T 645-2007, compatible with RS485 and Ethernet communication for easy system integration.

Strong Expandability: Optional DI/DO and AO modules for switch status monitoring and analog output, meeting customized requirements. Suitable for industrial, commercial, and power systems, providing accurate power monitoring solutions.