The Shelly Pro 3EM-3CT63 is a DIN rail-mountable single or three-phase energy meter that can operate independently in a local LAN or Wi-Fi network or connect to cloud-based automation platforms via Modbus, MQTT, HTTP, or WebSocket with TLS encryption.
Its special combined 3-phase current transformer (CT) is designed to be mounted directly over a circuit breaker.
It reports real-time data per phase/channel, including voltage, current, active and apparent power, and total energy consumption. Equipped with a built-in real-time clock, it stores up to 60 days of data in 1-minute intervals. Configuration and monitoring are fully accessible via the embedded web interface.
Note: The device does not include a built-in relay! Load switching is only possible using the Shelly Pro 3EM Switch Add-on module.
Main Features
- 4-quadrant power measurement
- DIN rail mountable design
- Compatible with single- and three-phase systems
- Non-contact current measurement via CT sensors
- Phase sequence detection (optional)
- Channel-to-channel calibration (min. 500 W load required)
- No load threshold: 30 VA/channel
- Optical pulse indication
- Real-time clock for accurate timekeeping during network outages
- Data logging: 60 days, 1-minute resolution
- External contactor control (requires Switch Add-on)
- Accuracy Class B (IEC 62053-21)
- Photovoltaic ready
Connectivity and Protocols
- LAN (Ethernet) – 1 × RJ45 port
- Wi-Fi – 802.11 b/g/n (2.4 GHz)
- Bluetooth 4.2 – for initial setup
- Supports Modbus, MQTT, RPC, WebSocket
- All inbound connections secured with TLS encryption
Technical Specifications
- Dimensions:
- Shelly Pro 3EM-3CT63: 94 × 19 × 69 mm
- Shelly 3CT63: 14 × 54 × 26 mm
- Enclosure: Plastic, white color
- Operating temperature: -20°C to 40°C
- Humidity: 30% to 70% RH
- Power supply: 100–260 V~ 50/60 Hz
- Power consumption: < 3 W
- Protection: Type B or C, 16 A, min. 6 kA breaking capacity
- Voltage range: 100–260 V (±1%)
- Current range: 0–63 A with accuracy:
- ±1% (2–63 A)
- ±2% (1–2 A)
- ±5% (0–1 A)
- Internal temperature sensor: Yes
- Data storage: At least 60 days with 1-minute resolution
- Data export: CSV and JSON (via RPC)
Firmware Capabilities
- 20 webhooks, each with up to 5 URLs
- Scriptable automation support
- MQTT compatible
- Encrypted communication via TLS
Controls and Indicators
- Button:
- Short press – toggle relay state (Switch Add-on required)
- 5 sec – activate AP mode
- 10 sec – factory reset
- LED Indicators:
- Red – Power supply connected
- Blue – AP mode
- Yellow – Wi-Fi connected, Shelly Cloud disabled
- Green – Wi-Fi and Shelly Cloud connected
- Red/Blue blinking – OTA update in progress
Installation Notes
- DIN rail mounting (Shelly Pro 3EM module)
- CT sensors clip directly over phase wires (on the MCB)
- Current direction: must follow K→L orientation
- CAUTION: Connect or disconnect the LAN cable only when the device is powered off!
Compatible Platforms and Integrations
- Shelly Cloud
- Home Assistant
- OpenHAB
- Domoticz
- REST API
- MQTT
Use cases
Industrial Power Distribution:
In industrial settings with complex power distribution systems, a combined 3-phase CT mounted over a circuit breaker can efficiently measure and monitor current levels. This is crucial for optimizing energy usage and identifying potential issues in real-time.
Commercial Buildings and Facilities:
For commercial buildings and facilities, where space is often limited in electrical panels, the compact design of the CT is beneficial. Mounting it directly over circuit breakers allows for efficient use of space while ensuring accurate current measurement.
Motor Control Centers (MCCs):
Motor control centers, which are commonly found in manufacturing plants and industrial facilities, often have multiple circuit breakers. A combined 3-phase CT mounted over each breaker provides an integrated solution for monitoring motor currents, aiding in preventive maintenance and troubleshooting.
Data Centers:
In data centers, where precise monitoring of power consumption is crucial, combined 3-phase CTs can be installed over circuit breakers to measure the current flowing through critical equipment.
Renewable Energy Installations:
Combined 3-phase CTs can be used in renewable energy installations, such as solar or wind power systems. By mounting them directly over circuit breakers in the control panels, accurate current measurements can be obtained for monitoring and control purposes.
Substation Monitoring:
In electrical substations, where space is often at a premium, combined 3-phase CTs can be advantageous. Installing them directly over circuit breakers helps in monitoring the current levels in the different phases, contributing to the overall stability and reliability of the substation.
Building Management Systems (BMS):
For intelligent building management systems, having accurate real-time data on current consumption is essential. Combined 3-phase CTs can be installed over circuit breakers to provide the necessary information for energy management and demand response strategies.
Power Quality Monitoring:
In applications where maintaining power quality is critical, such as in sensitive electronic equipment or medical facilities, combined 3-phase CTs can be used to monitor current waveforms and identify any anomalies that might affect the quality of power supplied.
Electrical Panel Upgrades:
During electrical panel upgrades or retrofits, space constraints may arise. A combined 3-phase CT, designed for direct mounting over circuit breakers, offers a space-saving solution without compromising accurate current measurement.
Smart Grid Deployments:
In the context of smart grids, where real-time data is essential for grid management and optimization, combined 3-phase CTs can be deployed over circuit breakers to provide accurate current information for monitoring and control purposes.
In each of these use cases, the combined 3-phase CT offers a space-efficient and integrated solution for current measurement, contributing to the overall efficiency, safety, and reliability of the electrical systems.
