Milesight CT3xx Smart Current Transformer
Specifications
- Product Name: Smart Current Transformer CT3xx
- Measuring Accuracy: Up to 3.3 kHz
- Power Source: Self-powered
- Sampling Rate: Up to 1s
- Installation: Non-invasive clamp design
- LED Indicator: Yes
- Support: External wire temperature sensor
- Phase Detection: Simultaneous detection of three phases
Product Usage Instructions
Ensure to follow these safety precautions to prevent any damage or accidents:
- Do not modify the device.
- Installation and maintenance should be done by a qualified service person.
- Avoid overloading the device.
- Use indoors only.
- Avoid extreme temperatures, water, and dusty environments.
- Avoid physical shocks and strong vibrations.
- The product CT3xx conforms to CE, FCC, and RoHS regulations.
- The device features a non-invasive clamp design for easy installation without power de-energizing.
FAQ
- Q: Can the device be used outdoors?
- A: No, the device is intended for indoor use only.
- Q: How often should the device be calibrated?
- A: It is recommended to calibrate the device annually or as per the specific requirements of your application.
- Q: What should I do if I encounter an alarm indication?
- A: If the LED indicator shows an alarm, refer to the user manual for troubleshooting steps or contact technical support for assistance.
Safety Precautions
Milesight will not shoulder responsibility for any losses or damages resulting from not following the instructions of this operating guide.
- The device must not be modified in any way.
- The installation and maintenance must be conducted by a qualified service person and should strictly comply with the electrical safety regulations of the local region.
- Do not overload the maximum capacity to avoid damage to the device.
- The device is intended only for indoor use. Do not place the device where the temperature is below/above the operating range.
- Do not place the device close to objects with naked flames, heat source (oven or sunlight), cold source, liquid, and extreme temperature changes.
- Keep the device away from water to prevent electric shock.
- Use the device opening clean and free of dust before installation. Dusty or dirty environments may prevent the proper operation of this device.
- Do not drop the device or subject it to physical shocks and strong vibration.
Declaration of Conformity
CT3xx conforms with the essential requirements and other relevant provisions of the CE, FCC, and RoHS.
Copyright © 2011-2024 Milesight. All rights reserved.
All information in this guide is protected by copyright law. Whereby, no organization or individual shall copy or reproduce the whole or part of this user guide by any means without written authorization from Xiamen Milesight IoT Co., Ltd.
- For assistance, please contact
- Milesight technical support:
- Email: iot.support@milesight.com
- Tel: 86-592-5085280
- Fax: 86-592-5023065
- Address: Building C09, Software Park III, Xiamen 361024, China
Revision History
| Date | Doc Version | Description |
| Jun 6, 2024 | V1.0 | Initial version |
Product Introduction
Overview
CT3xx is a LoRaWAN® Smart Current Transformer for monitoring energy consumption and analyzing usage remotely. CT3xx provides multiple current options to suit energy monitoring and supports sending threshold alarms. Its compact size enables quick and safe installation in any indoor space without de-energizing facilities, thereby simplifying the installation and saving costs. Compliant with Milesight LoRaWAN® gateway and Milesight Development Platform solution, CT3xx can be conveniently monitored via webpage remotely.
CT3xx is widely used for energy motoring of smart buildings, machine failure detection and prevention, etc.
Features
- Report the RMS current and accumulated current data by minutes
- High measuring accuracy with a sampling frequency of up to 3.3 kHz
- Self-powered, free from batteries or external wires
- Utilize a sampling rate of up to 1s for real-time monitoring and quick alarm response
- Non-invasive clamp design ensures easy and safe installation without the need for power de-energizing
- Equipped with LED indicator to indicate working status and alarms
- Support external wire temperature sensor for cable temperature measurement
- Enable simultaneous detection of three phases with a significantly wide optional detection range of either 500A or 1000A
- Compliant with standard LoRaWAN® gateways and network servers
- Compliant with the Milesight Development Platform
Hardware Introduction
Packing List
If any of the above items is missing or damaged, please contact your sales representative.
Hardware Overview
Button and LED Indicator
| Function | Action | LED Indicator |
| Normal Work | The device is functioning properly. | Blinking every 2s |
| Low Power Mode | The device measures and reports at a reduced rate. | Blinking every 5s |
| Low Voltage Mode | The device only measures at a reduced rate. | Blinking every 10s |
| Alarm | The current is over the threshold or measuring range, or the temperature is over the threshold. | Fast Blinking |
| Reboot | Quick press the RST button once. | Blinking Once |
Dimensions (mm)
CT305
CT310
Operation Guide
USB Configuration
CT3xx can be powered and configured via a Type-C port for configuration and debugging.
- Download ToolBox software from the Milesight website.
- Connect the device to a computer via the Type-C port.
- Open the ToolBox and select type as General, then click password to log into the ToolBox.(Default password: 123456)
- After logging into the ToolBox, you can check the device status and change device settings.
LoRaWAN Settings
LoRaWAN settings are used to configure the data transmission parameters in the LoRaWAN® network.
Basic LoRaWAN Settings:
CT3xx supports basic configurations like join type, App EUI, App Key, and other information. You can also keep all settings by default.
| Parameters | Description |
| Device EUI | Unique ID of the device which can also be found on the label. |
| App EUI | The default App EUI is 24E124C0002A0001. |
| Application Port | The port used for sending and receiving data, the default port is 85. |
| Join Type | OTAA and ABP modes are available. |
| Application Key | App key for OTAA mode, default is 5572404C696E6B4C6F52613230313823. |
| Device Address | DevAddr for ABP mode, default is the 5th to 12th digits of SN. |
| Network Session
Key |
Nwkskey for ABP mode, default is 5572404C696E6B4C6F52613230313823. |
| Application
Session Key |
The Appskey for ABP mode, default is 5572404C696E6B4C6F52613230313823. |
| RX2 Data Rate | RX2 data rate to receive downlinks. |
| RX2 Frequency/MHz | RX2 frequency to receive downlinks. |
| Spread Factor | If ADR is disabled, the device will send data via this spread factor. |
|
Confirmed Mode |
The device will resend data once if it does not receive the ACK packet from a network server. |
| Rejoin Mode | Reporting interval ≤ 35 mins: the device will send a specific number of LinkCheckReq MAC packets to the network server every reporting interval or every double reporting interval to validate connectivity; If there is no response, the device will re-join the network.
Reporting interval > 35 mins: the device will send a specific number of LinkCheckReq MAC packets to the network server every reporting interval to validate connectivity; If there is no response, the device will re-join the network. Note: Only OTAA mode supports rejoin mode. |
| Set the number of
packets sent |
When rejoin mode is enabled, set the number of LinkCheckReq packets sent.
Note: the actual sending number is Set the number of packets sent + 1. |
| ADR Mode | Allow the network server to adjust the data rate of the device. |
| Tx Power | Transmit power of the device. |
Note
- Please contact your sales representative for the device EUI list if there are many units.
- Please contact your sales representative if you need random App keys before purchase.
- Select OTAA mode if you use Milesight IoT Cloud to manage devices.
LoRaWAN Frequency Settings:
Select supported frequency and channels to send uplinks. Make sure the channels match the LoRaWAN® gateway.
If the device frequency is one of CN470/AU915/US915, you can enter the index of the channel that you want to enable in the input box, making them separated by commas.
Examples:
- 1, 40: Enabling Channel 1 and Channel 40
- 1-40: Enabling Channel 1 to Channel 40
- 1-40, 60: Enabling Channel 1 to Channel 40 and Channel 60
- All: Enabling all channels
- Null: Indicates that all channels are disabled
General & Alarm Settings
| Parameters | Description |
| Reporting Interval | The interval of reporting current data. Default: 10 mins, Range: 1 – 1440 mins
Note: when the device is under low power mode, the interval is fixed as 30 minutes; when the device is under low voltage mode, the device will stop reporting. The working mode can be judged by an LED indicator. |
| Change Password | Change the password of the device for ToolBox configuration. |
| Parameters | Description |
|
Alarm Reporting Interval (min) |
The interval to report alarm packet after alarm triggers. This
interval should be less than the reporting interval. |
| Alarm Reporting Times | Alarm packet report times after alarm triggers. |
Current Threshold (Phase x)
| Excessive Current Threshold | The maximum current threshold value. |
| Insufficient Current Threshold | The minimum current threshold value. |
Temperature
| Over | The maximum temperature threshold value. |
| Below | The maximum temperature threshold value. |
Note: The current over-range alarm is fixed as enabled, the alarm reporting interval is fixed as 5 minutes and the alarm reporting time is fixed as 3.
Maintenance
Upgrade
- Download firmware from the Milesight website to your PC.
- Go to Maintenance > Upgrade, click Browse to import firmware and click Upgrade to upgrade the device.
Backup
CT3xx supports configuration backup for easy and quick device configuration in bulk. Backup is allowed only for devices with the same model and LoRaWAN® frequency band.
- Go to Maintenance > Backup and Reset, and click Export to back up the device configuration.
- Click Browse to import the backup file, then click Import to load the configuration.
Reset and Reboot
Reset to Factory Default: Go to Maintenance > Backup and Reset of ToolBox, and click Reset to complete.
Reboot: Quick press the RST button once or send a downlink command to reboot.
Installation
Device Assembly
The CTs can be connected to the connectors of the transceiver without any specific order-matching requirement.
Antenna Installation
Rotate the antenna into the antenna connector. The antenna should be installed vertically and kept away from metal objects and obstacles.
Note: Keep the device away from metal objects, obstacles, or the environment surrounded by other electrical equipment that may cause interference. If necessary, please select a magnetic antenna.
Transformer Installation
Open the current transformer to clip it around a single-phase wire. Then close the clip with a slight “click” sound to make sure the clip firmly grips the wire.
Note:
- Do not place Phase wire and Neutral wire within a single current transformer.
- Please make sure at least connect a phase A CT to phase A wire, otherwise the device will be powered off.
Transceiver Installation
The transceiver can be put or hang in any suitable position or to be fixed via cable ties.
Cable Temperature Sensor Installation (Alternative)
CT3xx can monitor the temperature of one wire through the Cable Temperature Sensor, it will alarm when the temperature exceeds the threshold.
Pass the Cable Temperature Sensor around the tested wire, and then tighten the buckle. The other end is connected to the CT3xx device via the USB Type-C.
Note: Keep the Cable Temperature Sensor as close to the wire connector as possible to better detect the temperature.
Communication Protocol
All data are based on the following format (HEX), the Data field should follow little-endian:
| Channel1 | Type1 | Data1 | Channel2 | Type2 | Data2 | Channel 3 | … |
| 1 Byte | 1 Byte | N Bytes | 1 Byte | 1 Byte | M Bytes | 1 Byte | … |
For decoder examples, you can find at https://github.com/Milesight-IoT/SensorDecoders.
Basic Information
CT3xx reports basic information of the device whenever it joins the network.
| Channel | Type | Byte | Description |
|
ff |
01(Protocol Version) | 1 | 01=>V1 |
| 09 (Hardware Version) | 2 | 02 10=>V2.1 | |
| 0a(Software Version) | 2 | 01 01=>V1.1 | |
| ff(TSL Version) | 2 | 01 01=>V1.1 | |
| 0b (Power On) | 1 | Device is on | |
| 0f(Device Type) | 1 | 00 = Class A, 01 = Class B, 02 = Class C | |
| 16 (Device SN） | 8 | 16 digits |
Example
| ff0bff ff0101 ffff0101 ff166746d48016300014 ff090110 ff0a0101 ff0f00 | |||||
| Channel | Type | Value | Channel | Type | Value |
| ff | 0b
(Power On) |
ff
(Reserved) |
ff | 01
(Protocol Version) |
01
(V1) |
| Channel | Type | Value | Channel | Type | Value |
|
ff |
ff
(TSL Version) |
0101 (V1.1) |
ff |
16
(Device SN) |
6746d48
0163000 14 |
| Channel | Type | Value | Channel | Type | Value |
|
ff |
09
(Hardware Version) |
0110 (V1.1) |
ff |
0a (Software Version) | 0101 (V1.1) |
| Channel | Type | Value | |||
| ff | 0f
(Device Type) |
00
(Class A) |
Sensor Data
| Item | Channel | Type | Byte | Description |
| Phase A Total
Current |
03 |
97 |
4 |
UINT32/100, Unit: Ah, Resolution: 0.01 Ah Note: when it reaches the max value FFFFFFFF (42949672.95), it will clear to 0 automatically. |
| Phase B Total Current |
05 |
|||
| Phase C Total
Current |
07 |
|||
| Phase A Current | 04 |
98 |
2 |
UINT16/100, Unit: A, Resolution: 0.01 A Note: FFFF means collection failure. |
| Phase B Current | 06 | |||
| Phase C Current | 08 | |||
|
Phase A Current Alarm |
84 |
98 |
7 |
Max. Current (2B) + Min. Current (2B) + Latest Current (2B) + Alarm Status (1B)
Alarm Status: 01: Threshold alarm 02: Threshold alarm dismiss 04: Overrange alarm 08: Overrange alarm dismiss Note: Max./Min. Current means the maximum or minimum value between last report and the current report. |
|
Phase B Current Alarm |
86 |
|||
|
Phase C Current Alarm |
88 |
|||
|
Temperature |
09 |
67 |
2 |
INT16/10, Unit: °C
Note: FFFD means over-range temperature; FFFF means collection failure. |
|
Temperature Alarm |
89 |
67 |
3 |
Temperature (2B) + Alarm Status (1B) Temperature: INT16/10, Unit: °C Alarm Status:
01-Threshold alarm; 00-Threshold alarm |
| dismiss |
Example
- Periodic package: report as reporting interval (10 minutes by default).
039710270000 0498b80b 059710270000 0698b80b 079710270000 0898b80b 09673401
Channel Type Value Channel Type Value 03
97 (Phase A Total Current)
10 27 00 00=>00 00 27 10=10000/100
=100 Ah
04
98 (Phase A Current)
b8 0b=>0b b8 =3000/100
=30A
05
97 (Phase B Total Current)
10 27 00 00=>00 00 27 10=10000/100
=100 Ah
06
98 (Phase B Current)
b8 0b=>0b b8 =3000/100
=30A
07
97 (Phase C Total Current)
10 27 00 00=>00 00 27 10=10000/100
=100 Ah
08
98 (Phase C Current)
b8 0b=>0b b8 =3000/100
=30A
09
67(Temperature) 34 01=>01 34=308/10=30.8°C
- Phase A current alarm or alarm dismiss packet:
| 8498 b80b d007 c409 01 | ||
| Channel | Type | Value |
|
84 |
98(Phase A Current) |
Max. Current: b8 0b=>0b b8=3000/100=30A Min. Current: d0 07=>07 d0=2000/100=20A Latest Current: c4 09=>09 c4=2500/100=25A
Alarm Status: 01=> Threshold alarm |
Downlink Commands
CT3xx supports downlink commands to configure the device. The application port is 85 by default.
| Command | Channel | Type | Description |
| Reboot | ff | 10 | ff |
| Reporting Interval | ff | 8e | 00 + Interval Time(2B), unit: min |
|
Threshold Alarm |
ff |
06 |
9 Bytes, CTRL (1B) + Min (2B) + Max (2B) +
00000000(4B) CTRL: Bit2~Bit0: |
| 000 – disable; 001 – below; 010 – over; 011 – within; 100 – below or over
Bit5~Bit3: 001 – Phase A current; 010 – Phase B current; 011 – Phase C current; 100 – Temperature Bit7~Bit6: 00 Max./Min. Threshold unit: A or 0.1°C |
|||
|
Clear Accumulated Current |
ff |
27 |
01: Phase A; 02: Phase B; 03: Phase C
Note: when it reaches the max value FFFFFFFF (42949672.95Ah), it will clear to 0 automatically. |
| Alarm Reporting Interval | ff | 02 | 2 Bytes, unit: min, range: 1~1440 |
| Alarm Reporting Times | ff | f2 | 2 Bytes, range: 1~1000 |
Example
- Set the reporting interval as 20 minutes.
ff8e 00 1400 Channel Type Value ff 8e (Reporting Interval) 14 00=>00 14= 20 mins - Reboot the device.
ff10ff Channel Type Value ff 10 (Reboot) ff - Enable Phase A current threshold alarm and set the maximum threshold as 60A.
ff 06 0a00003c00 00000000 Channel Type Value ff
06
CTRL:0a=00001010=>over Phase A current maximum threshold Min: 00 00=0 Max: 3c 00=> 00 3c=60 A
- Set alarm reporting times as 10.
| fff2 0a00 | ||
| Channel | Type | Value |
| ff | f2 (Alarm Reporting Times) | 0a 00=>00 0a=10 |
CONTACT
- For assistance, please contact
- Milesight technical support:
- Email: iot.support@milesight.com
- Tel: 86-592-5085280
- Fax: 86-592-5023065
- Address: Building C09, Software Park III,
- Xiamen 361024, China
Documents / Resources
 |
Milesight CT3xx Smart Current Transformer [pdf] User Guide CT3xx Smart Current Transformer, CT3xx, Smart Current Transformer, Current Transformer, Transformer |
 |
Milesight CT3XX Smart Current Transformer [pdf] User Guide CT3XX Smart Current Transformer, CT3XX, Smart Current Transformer, Current Transformer, Transformer |