Three-phase measurement
Three-phase measurement (one-to-three clamps).
CT303 Milesight 300A Smart Current Transformer
300A Smart Current Transformer
Order codeCT303 In stockOfficial distributor
The CT303 is a 300A Smart Current Transformer. With a 300 A range and a Φ24.2 mm wire hole, it is sized for device-level and branch-circuit monitoring of small to medium electrical loads.
- LoRaWANLoRaWAN®
- PowerInduced current from
- ProtectionIP30
- Operating–20 … +1 °C
- In stockVilnius warehouse · EU
- In stockLondon warehouse · UK
Dispatch and lead time are confirmed in the quote.
- Official distributor
- 17+ years in IoT
- Installation support
Manufacturer warranty24 months
Overview
CT303 overview
Overview
The CT303 is a LoRaWAN three-phase smart current transformer for wireless energy monitoring and usage analysis. With a 300 A range and a Φ24.2 mm wire hole, it is sized for device-level and branch-circuit monitoring of small to medium electrical loads.
Three-Phase, Self-Powered Monitoring
A one-to-three clamp design measures up to three phases at once, and the device harvests power directly from the measured circuit, eliminating batteries and external wiring while keeping continuous operation.
High-Accuracy Measurement
With ±1% accuracy, sampling up to 3.3 kHz and a 1 s sampling rate, the CT303 reports RMS current and accumulated ampere-hours in real time for detailed energy analysis.
Smart Alerts
Configurable threshold, over-current, wire-temperature and low-voltage alerts (with an LED indicator) enable swift action, with an optional external NTC sensor for cable temperature.
Non-Invasive Installation
The split-core clamp attaches around existing wires without de-energizing the circuit, so it deploys quickly in distribution boxes for retrofit projects without downtime.
Integration
Compliant with standard LoRaWAN gateways and the Milesight Development Platform, the CT303 forwards data to BMS or energy-management systems for centralised monitoring.
Key features
Self-powered from the measured circuit
Self-powered from the measured circuit, no batteries.
± 1% accuracy
± 1% accuracy, up to 3.3 kHz sampling.
Real-time accumulated ampere-hours
Real-time accumulated ampere-hours (1 s).
Threshold
Threshold, over-current, temperature & low-voltage alerts.
Non-invasive split-core clamp install
Non-invasive split-core clamp install.
Optional external wire temperature sensor
Optional external wire temperature sensor.
FUOTA firmware updates
FUOTA firmware updates.
Technical data
CT303 specifications
| Specifications | |
|---|---|
| Detection Parameter | RMS current |
| Sampling Frequency | 3.3 kHz |
| Working Frequency | 50 ~ 60 Hz |
| Rated Primary Current (per CT) | 300 Arms |
| Rated Secondary Current | 150 mArms |
| Minimum Reporting Current | 3 Arms (1 min interval); 2.5 Arms (10 min interval) |
| Accuracy | ± 1% |
| Resolution | 1 mA |
| Temperature Sensor | 1 × NTC sensor, −20 °C ~ 100 °C, ± 1% (optional) |
| Specifications | |
| Protocol | LoRaWAN® |
| Antenna Connector | 1 × 50 Ω SMA connector (centre pin: SMA female) |
| Frequency | 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 |
| Mode | OTAA/ABP Class A |
| Specifications | |
| Button | 1 × reboot button |
| LED Indicator | 1 × status / alarm indicator |
| Port | 1 × USB Type-C for power, configuration, console or temperature-sensor connection |
| Specifications | |
| Configuration | USB Type-C or downlink |
| Advanced Feature | Threshold alarm, overrange alarm, FUOTA |
| Specifications | |
| Power Supply | Induced current from the measured circuit; or 5 V via USB Type-C |
| Insulation Voltage | 3 kVac (r.m.s.) (1 mA / 1 min) |
| Colour / Material | Blue, PBT + PC (UL94 V0) |
| Cable Length | 1 m |
| Operating Temperature | Transceiver: −20 °C ~ 70 °C; CT clamp: −40 °C ~ 55 °C |
| Relative Humidity | ≤ 95% (non-condensing) |
| Ingress Protection | IP30 |
| Dimensions | Transceiver: 38 × 34.5 × 16 mm; CT clamp: 56.5 × 36.5 × 68.5 mm; wire hole: Φ 24.2 mm |
| Weight | Transceiver: 13.05 g; per CT clamp: 250 g |
| Installation | Transceiver: cable-tie mounting; CT clamp: suspended on the testing conductor |
| Specifications | |
| Regulatory | CE, FCC, UL508 |
No specification rows match the filter.
Applications
CT303 applications
Smart Buildings
Branch circuits and equipment such as pumps, fans and rooftop HVAC are monitored phase by phase to track energy trends and detect anomalies, all without power interruption.
Facilities & Equipment Rooms
Compressors, elevators and small distribution panels gain non-invasive current monitoring for status detection and predictive maintenance.
Energy Management
Real-time ampere-hour tracking supports energy-saving programmes and load analysis across departments, with wireless LoRaWAN backhaul.
Retrofit Projects
Split-core clamps fit existing wiring in commercial and industrial sites, enabling fast deployment without cutting wires or shutting down equipment.
Questions
CT303 questions and answers
How is the CT303 powered?
Induced current from, according to the specification.
What ingress protection does the CT303 have?
IP30, according to the specification.
What is the operating temperature of the CT303?
–20 … +1 °C, according to the specification.
What lorawan does the CT303 provide?
LoRaWAN®, according to the specification.
Request a quote
CT303 price and lead time
Tell us the quantity and the delivery country. We reply within one working day with the price, stock at the nearest warehouse and the dispatch date.
European headquarters+370 655 51654[email protected]
United Kingdom branch+44 7425 726932[email protected]
- Company code306755852
- VAT numberLT100017217417
- Official distributor
- 17+ years in IoT
- Installation support
Manufacturer warranty24 months
