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Protecting Shelly Pro 3EM from Overvoltage and Undervoltage

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Introduction

Voltage fluctuations can lead to significant damage to electrical devices, including monitoring equipment like the Shelly Pro 3EM. To ensure the safe and reliable operation of the Shelly Pro 3EM itself, implementing over- and under- voltage protection is recommended. Based on the provided electrical diagram, this guide outlines a solution to safeguard the Shelly Pro 3EM from voltage irregularities.

Overview

The Shelly Pro 3EM is a sophisticated three-phase energy meter used for monitoring and automation. While it provides detailed insights into voltage, current, power, and energy consumption, the device itself requires protection from extreme voltage fluctuations to ensure continued performance and durability.

The attached diagram illustrates how to configure a system for protecting the Shelly Pro 3EM from both over and under voltage conditions.

PRO 3EM Protection.pdf

Prerequisites

Before implementing over- and under- voltage protection for the Shelly Pro 3EM, several prerequisites must be met to ensure proper installation and functionality. A reliable Miniature Contactor Relay or Auxiliary Relay must be available to facilitate automated disconnection during voltage anomalies. It is essential to have an External Phase Monitoring Relay configured to detect and respond to over and under voltage conditions. A Fuse Disconnector is required to protect and/or isolate the control circuit, safeguarding it from potential faults or overcurrent conditions. Additionally, the system wiring should adhere to the provided diagram, and professional installation by a certified electrician is recommended to ensure compliance with safety standards.

External equipment used:

  • Fuse Disconnector (-FU1):

    • Manufacturer: ABB

    • Description: E90 FUSE HOLDER 4P 32A

    • Catalog No.: 2CSM204723R1801

  • Phase Monitoring Relay (-FS1):

    • Manufacturer: ABB

    • Description: CM-PVE Phase monitoring relay 1n/o, L1,2,3-N=185-265VAC

    • Catalog No.: 2CSM204723R1801

  • Miniature Contactor Relay or Auxiliary Relay (-KA1):

    • Manufacturer: ABB

    • Description: MCRA040ATN Mini Contactor Relay 4NO 220-240V 50Hz/240-277V60Hz

    • Catalog No.: MCRA040ATN

Step-by-Step Instructions

  • Voltage Protection Device Setup:

    • Install an external over and under voltage protection relay upstream of the Shelly Pro 3EM.

    • This device monitors voltage levels in the system and isolates the Shelly Pro 3EM when voltage exceeds safe limits.

  • Threshold Configuration:

    • Configure the external protection device to disconnect the circuit if:

      • Overvoltage: Voltage exceeds the maximum operating limit of the Shelly Pro 3EM.

      • Undervoltage: Voltage drops below the minimum required threshold for safe operation.

  • Shelly Pro 3EM Connection:

    • Wire the Shelly Pro 3EM to the electrical system as shown in the diagram.

    • Ensure the protective device is installed between the power source and the Shelly Pro 3EM to safeguard the energy meter.

  • System Integration:

    • Integrate the Shelly Pro 3EM with monitoring tools to track voltage stability and performance.

    • Use the Shelly app or compatible platforms to receive alerts and analyze voltage trends.

  • Alert Configuration /Optional/:

    • Enable notifications for any voltage anomaly detected by the external protection device (if supported).

    • Configure the system to notify users of disconnection events caused by unsafe voltage levels (if supported).

Key Features of the System

  • Voltage Monitoring: Continuous tracking of voltage levels by the protection device to prevent damage.

  • Automated Isolation: Disconnects the Shelly Pro 3EM during overvoltage or undervoltage events.

  • Real-Time Alerts: Immediate notifications for voltage-related events affecting the energy meter.

  • Enhanced Safety: Protects the Shelly Pro 3EM, ensuring long-term reliability.

  • Smart Integration: Maintains compatibility with existing automation systems for holistic management.

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