Available in 300A, 500A, and 1000A models, the CT3xx iot current sensor supports reliable current monitoring from device-level circuits to main
power systems, with customizable measuring ranges available for specific project requirements.
CT3xx
LoRaWAN® Current Transformer
The CT3xx LoRaWAN® current sensor enables wireless current measurement with non-intrusive split-core clamp installation and 300A/500A/1000A current ranges. Designed for energy trend monitoring, phase-level sub-metering, and equipment status detection, it simplifies current monitoring without complex wiring.
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- IoT LoRaWAN® Series
- CT303/CT305/CT310
300A to 1000A LoRaWAN® Current Sensor for Flexible Current Monitoring
CT303
Current Capacity
300A
Wire Hole Size
Φ24 mm
Suitable for device-level or branch-circuit monitoring in small to medium electrical loads such as pumps, fans, air handling units, rooftop HVAC units, compressors, elevators, small distribution panels, etc.
CT305
Current Capacity
500A
Wire Hole Size
Φ36.6 mm
Suitable for area-level monitoring or medium-to-large equipment groups with higher power demand such as floor-level distribution panels, chiller pumps, cooling tower systems, production lines, UPS circuits, grouped HVAC equipment.
CT310
Current Capacity
1000A
Wire Hole Size
Φ51 mm
Suitable for main power circuits, large equipment, or high-capacity electrical systems such as building main incoming lines, factory main distribution cabinets, large chillers, data center power circuits, EV charging stations, transformer low-voltage sides.
LoRaWAN® Current Sensor with Accuracy, Flexibility, and Self-Powered Design
High-accuracy Current Measurement from 2.5A
The CT3xx IoT current sensor features ±1% accuracy, a high sampling frequency of up to 3.3kHz, and a low startup current of 2.5A, enabling stable low-current monitoring and detailed current data collection for accurate energy consumption analysis.
Multi-Target Measurement with Wireless Current Sensor
With a one-to-three design, the current transformer can be applied to measuring up to three different objects' electricity.
Versatile & Non-Invasive Installation
The user-friendly wireless current sensor features a clamp probe design for non-invasive and quick installation, eliminating the risk of circuit damage or power interruptions. Available in multiple wire hole sizes(24mm/36.6mm/51mm) to accommodate various wire thicknesses, ensuring broad compatibility across applications.
Self-Powered: No Batteries, No Limits
The CT3xx Wireless Smart Current Transformer is designed to derive power directly from the measured circuit, eliminating the constraints of batteries while ensuring seamless operation.
Wireless Current Monitoring with Self-Powered LoRaWAN® Design
Smarter Energy Tracking
Real-Time Alerts
Simple Cable-Free Deployment
Efficient Energy Tracking At One-Second Interval
Calculate accumulated ampere-hours in real time at a one-second interval. This enables precise current consumption monitoring and analysis, achieving goals such as energy conservation and reduced energy costs, without relying on a specific platform and helping lower overall solution costs.
12-Hour Standby
Designed with low power consumption and low startup current, CT3xx wireless current transformer efficiently harvests power from the measured circuit and supports up to 12 hours of standby operation after power-off. This helps maintain monitoring continuity for periodically operating equipment or circuits with extended downtime.
Current Threshold Alert
Set minimum and maximum current thresholds, and receive instant alarms upon threshold triggers for swift action.
Over-Current Alert
Receive instant alerts when the actual current exceeds the rated limit, accompanied by a smart LED indicator flashing every 2 seconds for swift visual confirmation of the alarm status.
Temperature Threshold Alert
An external wire temperature sensor is available, triggering alerts when the wire temperature reaches a set threshold.
Low-Voltage Alert
Receive instant alerts when the capacitor voltage enters low-voltage mode, helping users quickly distinguish power-off shutdown from poor signal or device removal.
Cable-Free Deployment
Say goodbye to the hassle of wires. This simplifies the installation process, reduces labor costs, and allows for more flexible placement.
Efficient LoRaWAN® Transmission
By utilizing the global IoT standards of LoRaWAN®, the CT3xx enables seamless wireless data transmission from electrical distribution panels across multiple stories of commercial and industrial buildings, ensuring strong stability, excellent penetrability, and broad compatibility.
Multiple Antenna Types
CT3xx is equipped with a high-gain antenna, ensuring stable signal transmission. Moreover, the mini stubby antenna and magnetic antenna are also offered as optional choices to meet your specific needs.
Complete Data Loop for Smart Current Monitoring
The smart current transformer wirelessly transmits on-site current data to a LoRaWAN® gateway and supports integration with standard LoRaWAN® gateways, network servers, and mainstream LNS platforms such as AWS, Actility, ChirpStack, Daizy, TTI, and LORIOT. Through protocols including Modbus, BACnet, HTTP(S), and MQTT(S), the gateway forwards data to platforms, BMS, or energy management systems, building a complete data loop for centralized current monitoring and analysis.
IoT Current Sensor for Three-Phase Current Monitoring Across
High-Consumption Facilities
The CT3xx IoT current sensor is designed for three-phase current monitoring in factories, commercial buildings, schools, hospitals, and other high-consumption facilities. With 300A, 500A, and 1000A current ranges, it helps users monitor equipment- or area-level energy trends, analyze phase-level current consumption, and support data-driven energy optimization without complex wiring or power interruption.
Three-Phase Energy Monitoring for Factories and Commercial Buildings
In factories, commercial buildings, schools, hospitals, and other high-consumption facilities, CT3xx helps monitor energy usage at the equipment, system, or area level. With non-intrusive three-phase current measurement and LoRaWAN® wireless transmission, it is suitable for monitoring HVAC systems, production equipment, pumps, compressors, elevators, and distribution branches. The collected current data helps users understand consumption trends, identify high-energy loads, and provide practical data references for energy optimization, while remaining more suitable for operational monitoring than billing-grade metering.
Phase-Level Current and Ampere-Hour Tracking
For three-phase circuits that require phase-level visibility, CT3xx measures A/B/C phase current values and calculates accumulated ampere-hours in real time. Combined with configured voltage and power factor, it helps estimate energy consumption and analyze load distribution across each phase. This is useful for distribution panels, three-phase motors, HVAC units, pumps, and industrial equipment, helping users detect phase imbalance, compare phase-level consumption, and improve power usage visibility.
Non-Intrusive Current Sensor Installation in Electrical Distribution Boxes
CT3xx is designed for installation in building or factory distribution boxes, where fast deployment and minimal disruption are essential. Its split-core clamp probes can be attached directly around existing wires, while the main unit can be mounted or suspended near the panel. This makes it suitable for retrofit projects in commercial buildings, factories, campuses, and equipment rooms, enabling current monitoring without cutting wires, damaging circuits, or shutting down equipment.
Large-Current Equipment Monitoring
With 300A, 500A, and 1000A measuring ranges, CT3xx supports current monitoring for large equipment and high-capacity electrical systems. It can be applied to factory main distribution cabinets, large chillers, cooling tower systems, production lines, compressors, elevator systems, UPS circuits, and other high-current loads. By capturing current changes and operating trends, CT3xx helps users monitor equipment status, analyze power demand, and support more informed maintenance and energy management decisions.
Milesight Full Wireless Current Sensors for All Your Needs
| Occupancy series | CT10x LoRaWAN® Current Transformer  | CT3xx LoRaWAN® Current Transformer  | CTH01 Smart Power Monitor Hub  |
|---|---|---|---|
| Sampling Frequency | 3.3kHz | 3.3kHz | 8kHz |
| Measuring Range | Current: 100A / 250A / 500A | Current: 300A / 500A / 1000A | Voltage: 100–500VAC; Current: 100A / 300A / 500A / 1000A / 4000A |
| Overview | Single-phase current monitoring terminal focused on current data collection and energy consumption trend analysis | Three-phase current monitoring terminal supporting independent monitoring of three-phase circuits | Power quality monitoring terminal covering both current and voltage monitoring |
| Application Scenarios | Commercial building distribution panels and residential applications | Industrial parks and large factory distribution panels | Power quality monitoring, multi-circuit monitoring, and mixed-load monitoring scenarios |
Proven Across Industries
Smart Energy and Water Management for a Multi-Site Hotel Group
Dakota Hotels deployed a scalable, estate-wide IoT solution across six luxury hotel sites in the UK. The project delivers real-time visibility into energy and water consumption, early leak detection, and automated compliance monitoring — all without disrupting hotel operations or guest experience.
Know More about the Case →
Non-Intrusive Energy Management Insights for Industrial Machines
The project successfully deployed a non-intrusive power monitoring solution featuring Milesight Smart Current Transformers to provide real-time energy insights without disrupting operations. This IoT-based system enables remote monitoring, predictive maintenance and data-driven decision-making, helping to optimize efficiency and reduce costs. Around 30 devices were deployed across 10 machines and the current transformers were deployed on almost every machine in the factory.
Know More about the Case →Related Products
Milesight offers a range of LoRaWAN® energy monitoring products to support different current monitoring needs, from branch circuits and three-phase loads to centralized panel applications. Combined with Milesight LoRaWAN® gateways, they help build a flexible and scalable wireless energy monitoring network.
CTH01
Smart Power Monitor Hub
CTH01
Smart Power Monitor Hub
- 12-in-1 Multi-Circuit Energy Monitoring
- Flexible Single-Phase & Three-Phase Configuration
- Non-intrusive Magnetic Voltage Measurement
- Professional Analytics with Up to 8kHz Sampling Frequency
CT10x
Smart Current Transformer
CT10x
Smart Current Transformer
- Self-Powered Operation
- Superior Accuracy with Up to 3.3kHz Frequency
- Real-time Accumulated Ampere Hour Calculation
- Non-invasive Installation
UG56
Industrial LoRaWAN® Gateway
UG56
Industrial LoRaWAN® Gateway
- Industrial-Grade Design
- Free Embedded Network Server
- Multiple Backhaul Connectivities
- Gateway Fleet
Related Resources
You May Want to Know
What are the advantages of a LoRaWAN® wireless current sensor compared with a wired current sensor?
Compared with traditional wired current sensors, a LoRaWAN® wireless current transformer greatly simplifies deployment by eliminating the need for long signal cables between electrical panels, meters, or monitoring platforms. With split-core clamp installation, it can be installed non-intrusively around existing wires, helping reduce wiring work, installation time, and retrofit costs. It is especially suitable for distributed electrical panels, branch circuits, and equipment monitoring across buildings, factories, and commercial facilities. By transmitting data wirelessly to a LoRaWAN® gateway, users can build a scalable current monitoring network with less infrastructure complexity and easier expansion for future energy management needs.
What is the difference between single-phase and three-phase current monitoring, and how should I choose the right product?
Single-phase current monitoring is commonly used for individual circuits, branch circuits, small equipment, lighting, pumps, fans, and other device-level loads. It is suitable when only one live wire or one independent load needs to be monitored. For these applications, Milesight CT10x is typically recommended.
Three-phase current monitoring is designed for larger electrical systems where power is distributed across three phases. It is commonly used in factories, commercial buildings, distribution panels, HVAC systems, motors, compressors, elevators, and other high-power equipment. When A/B/C phase current monitoring, phase-level consumption analysis, or high-current load monitoring is required, Milesight CT3xx is the preferred choice.
For centralized monitoring of multiple circuits within one electrical panel, Milesight CTH01 can be used as a high-density current monitoring option. Users can select CT10x for single-phase or branch-circuit monitoring, CT3xx for three-phase and high-current applications, and CTH01 for centralized multi-circuit panel monitoring.
What is the difference between EnOcean and LoRaWAN® for wireless current monitoring?
EnOcean is commonly used for short-range, ultra-low-power building automation devices, such as switches, occupancy sensors, and basic indoor controls. It is suitable for local building scenarios where devices are deployed within a limited area and connected to nearby controllers or gateways.
LoRaWAN® is designed for long-range, low-power IoT communication, making it more suitable for distributed current monitoring across commercial buildings, factories, campuses, and multi-floor electrical rooms. For wireless current transformers, LoRaWAN® helps transmit current data from electrical panels or equipment to gateways over longer distances, reducing wiring complexity and supporting scalable deployment.
For projects that require wide-area coverage, centralized energy monitoring, integration with IoT platforms, BMS, or EMS, a LoRaWAN® wireless current transformer is generally the better choice. EnOcean may be more suitable for localized building automation, while LoRaWAN® offers greater flexibility for large-scale current monitoring and energy management applications.
What is a clamp-on current transformer and why is it useful for current monitoring?
A clamp-on current transformer is designed to measure current by clamping around an existing wire or cable, without cutting the circuit or interrupting equipment operation. This non-intrusive installation method makes it especially suitable for retrofit projects, distribution boxes, branch circuits, and large electrical equipment where downtime should be avoided.
For wireless current monitoring, clamp-on current transformers such as Milesight CT Series help simplify deployment, reduce wiring work, and collect current data from different circuits or equipment. Users can monitor energy consumption trends, analyze load status, and support equipment operation management with less installation complexity.
Specifications
- CT303
- CT305
- CT310
| Electrical Measurement | |
|---|---|
| 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 Current1 | 3Arms (1min Interval) 2.5Arms (10min Interval) |
| Accuracy | ±1 % |
| Resolution | 1 mA |
| Temperature Sensor | Sensor type: 1 × NTC Sensor Measuring range: -20°C ~ 100°C Measuring accuracy: ±1 % |
| Wireless Transmission | |
| Protocol | LoRaWAN® |
| Antenna Connector | 1 × 50 Ω SMA Connector (Center 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 | -137dBm |
| Mode | OTAA/ABP Class A |
| Others | |
| Button | 1 × Reboot Button |
| LED Indicator | 1 × Status/Alarm Indicator |
| Port | 1 × USB Type-C for Power Supply, Configuration, Console or Cable Temperature Sensor Connection |
| Software | |
| Configuration | USB Type-C or Downlink |
| Advanced Feature | Threshold Alarm, Overrange Alarm, FUOTA |
| Physical Characteristics | |
| Power Supply | 1. Induced current power supply2 2. 5V by USB Type-C Port |
| Insulation Voltage | 3kVac(r.m.s)(1mA/1min) |
| Color/ Material | Blue, PBT+PC (UL94 V0) |
| Cable Length | 1m |
| Operating Temperature | Transceiver: -20°C~70°C (-4°F~158°F) CT Clamp: -40°C~55°C (-40°F~131°F) |
| Storage Temperature | Transceiver: -25°C~80°C (-13°F~176°F) CT Clamp: -40°C~55°C (-40°F~131°F) |
| Relative Humidity | ≤ 95% (Non-condensing) |
| Ingress Protection | IP30 |
| Dimensions | Transceiver: 38 × 34.5 × 16 mm (1.5 × 1.36 × 0.63 in) CT Clamp:56.5 × 36.5 × 68.5 mm (2.24 × 1.44 × 2.70 in) Wire Hole: Ф 24.2 mm(Ф 0.95 in) |
| Weight | Transceiver: 13.05 g Per CT Clamp: 250 g |
| Installation | Transceiver: Cable-tie Mounting (under integrated mode) CT Clamp: Suspended on the Testing Conductor |
| Approvals | |
| Regulatory | CE, FCC, UL508 |
1The minimum current to report data under different reporting intervals when the device is powered by the testing conductor. To measure lower currents, the device must be powered via USB.
2When the device is powered by the testing conductor, it can only be powered by phase A wire.
| Electrical Measurement | |
|---|---|
| Detection Parameter | RMS Current |
| Sampling Frequency | 3.3 kHz |
| Working Frequency | 50~60 Hz |
| Rated Primary Current (Per CT) | 500 Arms |
| Rated Secondary Current | 150 mArms |
| Minimum Reporting Current1 | 5Arms (1min Interval) 4.5Arms (10min Interval) |
| Accuracy | ±1 % |
| Resolution | 1 mA |
| Temperature Sensor | Sensor type: 1 × NTC Sensor Measuring range: -20°C ~ 100°C Measuring accuracy: ±1 % |
| Wireless Transmission | |
| Protocol | LoRaWAN® |
| Antenna Connector | 1 × 50 Ω SMA Connector (Center 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 | -137dBm |
| Mode | OTAA/ABP Class A |
| Others | |
| Button | 1 × Reboot Button |
| LED Indicator | 1 × Status/Alarm Indicator |
| Port | 1 × USB Type-C for Power Supply, Configuration, Console or Cable Temperature Sensor Connection |
| Software | |
| Configuration | USB Type-C or Downlink |
| Advanced Feature | Threshold Alarm, Overrange Alarm, FUOTA |
| Physical Characteristics | |
| Power Supply | 1. Induced current power supply2 2. 5V by USB Type-C Port |
| Insulation Voltage | 3kVac(r.m.s)(1mA/1min) |
| Color/ Material | Blue, PBT+PC (UL94 V0) |
| Cable Length | 1m |
| Operating Temperature | Transceiver: -20°C~70°C (-4°F~158°F) CT Clamp: -40°C~55°C (-40°F~131°F) |
| Storage Temperature | Transceiver: -25°C~80°C (-13°F~176°F) CT Clamp: -40°C~55°C (-40°F~131°F) |
| Relative Humidity | ≤ 95% (Non-condensing) |
| Ingress Protection | IP30 |
| Dimensions | Transceiver: 38 × 34.5 × 16 mm (1.5 × 1.36 × 0.63 in) CT Clamp: 68 × 86 × 41.8 mm (2.68 × 3.39 × 1.65 in) Wire Hole: Ф 36.5 mm(Ф 1.44 in) |
| Weight | Transceiver: 13.05 g Per CT Clamp: 276.75g |
| Installation | Transceiver: Cable-tie Mounting (under integrated mode) CT Clamp: Suspended on the Testing Conductor |
| Approvals | |
| Regulatory | CE, FCC, UL508 |
1The minimum current to report data under different reporting intervals when the device is powered by the testing conductor. To measure lower currents, the device must be powered via USB.
2When the device is powered by the testing conductor, it can only be powered by phase A wire.
| Electrical Measurement | |
|---|---|
| Detection Parameter | RMS Current |
| Sampling Frequency | 3.3 kHz |
| Working Frequency | 50~60 Hz |
| Rated Primary Current (Per CT) | 1000 Arms |
| Rated Secondary Current | 150 mArms |
| Minimum Reporting Current1 | 10Arms (1min Interval) 8.5Arms (10min Interval) |
| Accuracy | ±1 % |
| Resolution | 1 mA |
| Temperature Sensor | Sensor type: 1 × NTC Sensor Measuring range: -20°C ~ 100°C Measuring accuracy: ±1 % |
| Wireless Transmission | |
| Protocol | LoRaWAN® |
| Antenna Connector | 1 × 50 Ω SMA Connector (Center 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 | -137dBm |
| Mode | OTAA/ABP Class A |
| Others | |
| Button | 1 × Reboot Button |
| LED Indicator | 1 × Status/Alarm Indicator |
| Port | 1 × USB Type-C for Power Supply, Configuration, Console or Cable Temperature Sensor Connection |
| Software | |
| Configuration | USB Type-C or Downlink |
| Advanced Feature | Threshold Alarm, Overrange Alarm, FUOTA |
| Physical Characteristics | |
| Power Supply | 1. Induced current power supply2 2. 5V by USB Type-C Port |
| Insulation Voltage | 3kVac(r.m.s)(1mA/1min) |
| Color/ Material | Blue, PBT+PC (UL94 V0) |
| Cable Length | 1m |
| Operating Temperature | Transceiver: -20°C~70°C (-4°F~158°F) CT Clamp: -40°C~55°C (-40°F~131°F) |
| Storage Temperature | Transceiver: -25°C~80°C (-13°F~176°F) CT Clamp: -40°C~55°C (-40°F~131°F) |
| Relative Humidity | ≤ 95% (Non-condensing) |
| Ingress Protection | IP30 |
| Dimensions | Transceiver: 38 × 34.5 × 16 mm (1.5 × 1.36 × 0.63 in) CT Clamp: 97.1 × 119 × 59.5 mm (3.82 × 4.69 × 2.34 in) Wire Hole: Ф 51 mm(Ф 2.01 in) |
| Weight | Transceiver: 13.05 g Per CT Clamp: 855.55 g |
| Installation | Transceiver: Cable-tie Mounting (under integrated mode) CT Clamp: Suspended on the Testing Conductor |
| Approvals | |
| Regulatory | CE, FCC, UL508 |
1The minimum current to report data under different reporting intervals when the device is powered by the testing conductor. To measure lower currents, the device must be powered via USB.
2When the device is powered by the testing conductor, it can only be powered by phase A wire.
LoRaWAN® Magnetic Antenna
Optional
- Frequency Range:470 MHz
- Gain:2 dBi
- Connector Type:SMA-J
- Height:185.35 mm
- Color:Black
- Cable Length:1.5m
- Applicable Products:CT101/CT103/CT105/CT303/CT305/CT310
LoRaWAN® Magnetic Antenna
Optional
- Frequency Range:860-930 MHz
- Gain:≤1dBi
- Connector Type:SMA-J
- Height:111 mm
- Color:Black
- Cable Length:1.5m
- Applicable Products:CT101/CT103/CT105/CT303/CT305/CT310