Transformer current transducer CT3 series

clampthree-phaseAC

Overview
The CT3xx series consists of LoRaWAN® smart split-core clamp-on current transformers for non-intrusive current measurement and energy monitoring. Available in 300 A, 500 A and 1000 A variants (CT303 / CT305 / CT310), the CT3xx is intended for energy trend monitoring, phase-level sub-metering and equipment status detection in smart buildings, industrial sites and commercial deployments. It supports self-powered operation (harvesting power from the measured conductor) or external 5 V USB Type-C power for low-current scenarios.

Key Features

• Non-intrusive split-core clamp design for quick retrofit installation without circuit interruption
• Self-powered harvesting from the conductor and optional USB Type-C 5 V external power
• High sampling frequency up to 3.3 kHz for accurate RMS current measurement
• High accuracy: ±1% (resolution 1 mA)
• One-to-three measurement capability (measure up to three circuits/objects)
• LoRaWAN® wireless transmission (OTAA/ABP, Class A) with 50 Ω SMA antenna connector
• Low startup and low reporting-current thresholds when externally powered for reliable low-current monitoring
• Configurable threshold alarms (over-current, min/max current, temperature threshold, low-voltage) and FUOTA support

Models and Typical Applications

• CT303 — 300 A, wire hole Ø24 mm: device-level or branch-circuit monitoring (pumps, fans, AHUs, small panels, rooftop HVAC, compressors, elevators)
• CT305 — 500 A, wire hole Ø36.6 mm: area-level or medium-to-large equipment groups (floor panels, chillers, cooling towers, production lines, UPS circuits)
• CT310 — 1000 A, wire hole Ø51 mm: main power circuits and large electrical systems (building mains, transformer LV sides, large chillers, EV charging, data center power circuits)

Wireless, Integration & Communication

• Protocol: LoRaWAN® (OTAA / ABP, Class A)
• Frequencies supported: CN470 / IN865 / RU864 / EU868 / US915 / AU915 / KR920 / AS923-1/2/3/4 (region dependent)
• Tx Power: 16 dBm (868 MHz) / 20 dBm (915 MHz) / 19 dBm (470 MHz)
• Receiver sensitivity: -137 dBm
• Antenna: 50 Ω SMA connector (center pin: SMA female). Multiple antenna options available (high-gain, stubby, magnetic)
• Integrates with standard LoRaWAN gateways and mainstream LNS platforms; gateway-level translations enable forwarding to BMS/EMS via Modbus, BACnet, HTTP(S), MQTT(S)

Alarms & Monitoring

• Configurable current threshold alarms (min / max) with immediate alerts on triggers
• Over-current alarm with visual LED indication (flashing) for quick local confirmation
• Optional external wire temperature sensor with temperature-threshold alarm
• Low-voltage detection to distinguish power-off from poor contact or device removal

Installation & Mechanical

• Split-core clamp mounted on the conductor; transceiver module mountable with cable ties
• Non-invasive clamp-on installation — no circuit cutting or equipment shutdown required
• Cable length (CT clamp to transceiver): 1 m (standard)

Typical Use Cases

• Three-phase monitoring for factories, commercial buildings, campuses and high-consumption facilities
• Equipment-level and branch-circuit monitoring for HVAC systems, pumps, compressors, elevators and production lines
• Energy trend tracking, ampere-hour accumulation, phase imbalance detection and predictive/preventive maintenance

Documents & Tools
Datasheet and user guide are provided for technical details; payload decoders and integration guides are available for platform integration.

Technical specifications

• Measurement parameter: RMS current
• Sampling frequency: 3.3 kHz
• Operating frequency: 50–60 Hz
• Accuracy: ±1%
• Resolution: 1 mA
• Temperature sensor: 1 × NTC; measuring range -20 °C ~ 100 °C; accuracy ±1%
• LoRaWAN® protocol: OTAA / ABP (Class A)
• Antenna connector: 1 × 50 Ω SMA (center pin: SMA female)
• Regional frequencies: CN470 / IN865 / RU864 / EU868 / US915 / AU915 / KR920 / AS923-1/2/3/4
• Tx power: 16 dBm (868 MHz) / 20 dBm (915 MHz) / 19 dBm (470 MHz)
• Sensitivity: -137 dBm
• LED: 1 × status/alarm indicator; Button: 1 × reboot
• Port: 1 × USB Type-C (power, configuration, console, or external temperature sensor)
• Power supply: induced current power (self-powered) or 5 V via USB Type-C
• Insulation voltage: 3 kVac (r.m.s) (1 mA / 1 min)
• Material & color: Blue, PBT+PC (UL94 V0)
• Operating temperature: Transceiver -20 °C ~ 70 °C; CT clamp -40 °C ~ 55 °C
• Storage temperature: Transceiver -25 °C ~ 80 °C; CT clamp -40 °C ~ 55 °C
• Relative humidity: ≤ 95% (non-condensing)
• Ingress protection: IP30
• Transceiver dimensions: 38 × 34.5 × 16 mm
• Models / CT clamp details and minimum reporting currents: CT303 — 300 Arms (wire hole Ø24.2 mm), rated secondary 150 mArms, clamp weight ~250 g, minimum reporting current: 3 A (1 min) / 2.5 A (10 min); CT305 — 500 Arms (wire hole Ø36.5 mm), rated secondary 150 mArms, clamp weight ~276.75 g, minimum reporting current: 5 A (1 min) / 4.5 A (10 min); CT310 — 1000 Arms (wire hole Ø51 mm), rated secondary 150 mArms, clamp weight ~855.55 g, minimum reporting current: 10 A (1 min) / 8.5 A (10 min)
• Transceiver weight: ~13.05 g
• Installation: CT clamp suspended on conductor; transceiver mounted with cable ties
• Approvals: CE, FCC, UL508 (as indicated)