I. Requirements Analysis

The degree of conductor sag is one of the primary indicators for assessing whether a power line is operating healthily. Besides stress factors, meteorological conditions in the environment where overhead lines are located also affect sag magnitude, with temperature having a particularly noticeable impact. During summer when temperatures are high, the distance between the sag and the ground decreases. Excessive sag reduces the clearance to ground, potentially creating a risk of contact and electric shock. Conversely, insufficient sag increases the likelihood of accidents such as wire breakage, both of which compromise power supply stability and safety beneath the lines. To enhance sag monitoring capabilities, improve line safety and information management efficiency, and ensure reliable power supply for residents, Dingxin Smart Technology has introduced an online sag monitoring device for transmission line conductors.

II. Working Principle

The online sag monitoring device for transmission line conductors is primarily used to measure the distance to ground, sag angle, and skew angle of transmission lines. When monitoring jumper sag, the sensor is installed on the jumper; when monitoring insulator sag, the sensor is installed at the bottom or top end of the insulator string; when monitoring phase-to-phase sag within a span, the sag monitoring device is installed within the span between the two conductors requiring monitoring. The sag sensor utilizes laser sensing technology and low-power wireless transmission. It draws power from the high-voltage line, continuously collects sag data in real time, and transmits the monitored data via 4G/5G/GPRS/WIFI/OPGW fiber optic networks to the monitoring center. An alarm is triggered when the measured values exceed preset thresholds.

III. Features and Functions

1. Capable of directly measuring conductor sag or ground clearance, or collecting relevant measurement values such as conductor inclination angle, temperature, tension, and images that can be used to derive conductor sag or ground clearance through value transfer. It performs corresponding storage and calculations to determine conductor sag and ground clearance status quantities, then transmits the results via communication networks to the condition monitoring system. (Typically applicable when only one sag monitoring device is installed at a site, with no other monitoring devices present), or a condition monitoring proxy device.

2. Equipped with automatic data collection functionality, it automatically gathers parameters related to conductor sag or distance to ground at preset time intervals.

3. Equipped with controlled data acquisition capabilities, it can respond to remote commands to initiate data collection based on the configured acquisition method, automatic acquisition time, acquisition interval, and number of data points.

4. For online sag acquisition units, it is advisable to include functions for collecting power supply voltage and operating temperature data.

5. Equipped with network time synchronization capability. The unit shall be capable of receiving time synchronization commands from the condition monitoring system, synchronizing time once daily with an error not exceeding 5 seconds. The unit clock's time deviation within a 24-hour period shall be less than 1 second.

6. Equipped with data validity check and analysis capabilities, it performs preprocessing on collected data, automatically identifying and filtering out erroneous data.

7. Capable of performing primary calculations on raw measurement data to derive intuitive state data for conductor sag and ground clearance.

8. Should be capable of storing sag and ground clearance status data for at least 30 days, and is recommended to store raw measurement data for over 30 days.

9. Output information includes: wire sag, ground clearance status, power supply voltage, operating temperature, alarm signals, device heartbeat packets, response information, and communication connection status (including signal strength).

IV. Technical Specifications