Mar 19, 2018Indian power company Tata Power Delhi Distribution Ltd. (TPDDL) has launched an RFID- and GPS-based system to gain visibility into the locations of underground cable joints for workers searching for faults. The technology, consisting of active ultrahigh-frequency (UHF) RFID marker tags attached to joints, as well as handheld readers in the hands of personnel, was deployed across 1,200 cable routes in a phased approach beginning in 2015.
Since the system was installed, the company says, it has not only saved time for maintenance workers, but also ensured that any faults are located and corrected quickly. In fact, says Sunil Singh, TPDDL's chief operations and safety officer, since the technology was taken live, it has reduced the average time required to locate a cable splice from 90 minutes down to 45 only minutes.
TPDDL, a joint venture between the National Capital Territory of Delhi government and Tata Power Co., serves 1.8 million people in the North and Northwest portions of Delhi throughout an area measuring 510 square kilometers (197 square miles). The joint venture has an underground network of 3,100 kilometers (1,197 square miles) of 66-, 33- and 11-kilovolt cables, amounting to approximately 15,000 cable routes altogether. Managing those underground cables is a matter of regular maintenance, Singh explains, and occasionally responses to power failures.
Preventing failures is one of TPDDL's key goals, however. Any time there's a failure of this critical power delivery caused by an asset problem, the company says, the results can be customer dissatisfaction and a loss of revenue due to unserved energy, as well as high expenditures based on repair and replacement.
The cross-linked polyethylene (XLPE) underground cables are ideally maintenance-free equipment, Singh says. "Still, we carry out signature analysis of the underground network to monitor and diagnose the health of the cables," he states. In the event of a problem, the fault point is located using "fault location equipment" sensors on site. The soil is then excavated to identify the fault, and joints are thereby made in cables for restoration.
This kind of work is more challenging in a population-dense urban environment. Right-of-way (ROW) permission is required for excavation, Singh says. Additionally, he states, "Repairing and new laying of cables are really difficult and time-consuming." As cable joints age, there are higher failure rates requiring more servicing efforts. "Fault location in underground cable is a tedious job which requires high skill and considerable amount of time, due to unidentified cable routes especially for older cables."
With RFID and GPS mapping technology, identifying the route of underground power cable networks above the ground level becomes easier. In turn, that shortens the fault-finding time period. TPDDL first mapped out 1,200 cable routes using GPS technology, then installed 1,000 RFID-tagged markers as the first phase of the project. The collected data is then linked to the existing Geographical Information System (GIS) network.
At the center of the new solution is a rugged electronic ball marker known as the RFID Ball Marker, connected to the cable splices via a cable tie during any new cable installation, or in the course of operation and maintenance activity. The sealed ball contains an active UHF 3M 1400 Series iD Ball Marker. Relevant information, such as the make of a joint, the date of installation and the joint depth, are written to the RFID Ball Marker at the time of installation, using the handheld 3M Dynatel Locator reader, known as an RFID Detector. The location data is then updated in the software by linking it to the GPS Mapper's longitude and latitude.
For maintenance personnel, the system automates the collection of data related to joint maintenance history, including the date of installation, the make and type of the joint, and the depth at which it is buried. This helps with joint health monitoring and condition-based maintenance.
When a field worker goes to the site of a particular cable, he or she first tests the cables and then captures the fault length with the use of a cable fault locating system. The person verifies the fault in the GPS mapper software in order to know the exact location of the fault point, with the help of GPS Mapper. Once the fault is located and resolved, the new joints' attributes are written to the RFID marker. Following preparation, all relevant information regarding the new joints is stored in the company's GIS database software.
To date, the company has found that the technology cuts maintenance times in half. "Shorten time length in finding the cable fault is the key benefit," Singh says. It follows, he adds, that "Time saving in finding the fault is directly linked with the reliability of power supply, as well as the customer satisfaction."
For TPDDL, the next phase will involve equipping all additional cable routes with the RFID markers. This is the first time any power-distribution company has implemented the technology in India, Singh says. "We continuously innovate," he adds, with the intention of providing "world-class services to our consumers." The GPS and RFID system, he adds, will not only ensure efficient fault location, but also ill help to improve on reliability.
