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Electrical

1. Transmission/Distribution Line

2. What is Power Transmission Line? A power transmission line is a high-voltage electrical line that carries electrical energy from a power plant or generating station to a substation or distribution point, where it can be transformed and distributed to consumers. These lines are a crucial part of the electrical grid, enabling the efficient and reliable transmission of electricity over long distances. Power transmission lines typically operate at high voltages (ranging from 132kV to 1200 kV or more) to minimize energy losses during transmission. They are often supported by tall towers or poles, and can be overhead lines or underground cables.

3. The main components of a power transmission line include: Conductors (wires or cables) Towers or poles Insulators Transformers (at substations) Switchgear and control systems

4. Power transmission lines play a vital role in: Enabling long-distance energy transmission Connecting power plants to load centers Maintaining grid reliability and stability Supporting economic development and growth

5. Jumper Snapping   Jumper snapping incident happen due to Flow of high current, loose Connection, heavy fault . After B/D of Transmission line firstly check relay and then apply offline fault locator for identify the  fault distance. Line patrolling will be started as per relay fault   locator distance. finally identify the snapped Jumper, discharge said transmission line from both side then restoration work will

6. Jumper Snapping

7. Parts of Tower

8. Jumper Snapping

9. Case Study -1 Fault Detection and Restoration of 220KV Dehri-Pusauli Transmission Line Introduction: In this case study, we will explore how a fault in the 220KV Dehri–Pusauli transmission line was detected and fixed. This real-world scenario will show you how power companies quickly respond to technical issues to ensure uninterrupted electricity supply. Let’s break down the steps to understand how such incidents are managed .

10. The Problem (Fault Occurrence ): On 24th November 2020 , at 6:28 PM , the 220KV transmission line between Dehri and Pusauli suddenly tripped (meaning the power flow stopped ). Distance protection and earth fault relay , detected an issue and cut off power to prevent damage . Distance Protection: Detects faults based on the distance to the fault along the power line . Earth Fault Relay: Protects the system by detecting any ground faults (when electricity flows into the ground due to a problem ). The company used a tool called an offline fault locator , which found that the problem was 11.1 km away from Dehri . After identifying the issue, the State Load Dispatch Centre (SLDC) declared the line under breakdown and asked for line patrolling to check the problem.

11. 2. Finding the Fault (Patrolling ): The next day, 25th November 2020 , a team went out to patrol the line and check where exactly the fault occurred. They found that: The R-phase conductor (the top wire) had snapped between two towers (tower 28 and 29 ). The disc insulators (which hold the wire) at tower 28 were broken . Because the wire was snapped, the remaining wires and insulators at towers 27, 28, and 29 were under tension (pulled too tightly), which could cause further damage.

12. 3. Restoration Process( Repair Work ): Now that the problem was identified, it was urgent to fix it and restore power . The following steps were taken to fix the line : The restoration steps included : Mobilisation of an emergency gang with T & P for work site early morning on dated26.11.2020 Downloading of R and B Phase top conductor between tower location number 27-28& 28-29 and uploading of same conductor above said location numbers. Replacement of discs insulators and stringing of top phase at location number 28 . Repairing of snapped R phase conductor between location number 28-29. Hiring of 20 unskilled labours for harvesting of paddy crops(rice) on dated 25-26/11/2020. Demobilisation of an emergency gang from work site on dated 27/11/2020 in the morning. Despite challenges like wet fields , rain , and night-time work, the repairs were completed by the morning of 27th November 2020 , and the line was successfully recharged at 10:49 AM .

13. Case Study:2 Fault Detection and Restoration of 132KV Dehri–Sasaram Transmission Line Introduction : On 24th July 2021 , during a heavy storm with thunder and rain , the 132KV Dehri-Sasaram transmission line tripped at 02:49 hrs .. This case study explains the fault detection, identification, and restoration process, which was carried out urgently to restore power to the affected substations.

14. 1. The Problem (Fault Occurrence): During the storm, the B-phase conductor of the transmission line snapped from the disc insulator string . This caused the conductor to fall onto the conductors of a 33KV Toll Plaza feeder and an 11KV feeder, located between location number 01 and the GSS Sasaram gantry. The falling conductor caused significant damage to the charged feeders, making the replacement of the damaged conductor essential . Due to the critical role of this transmission line in supplying power to GSS Sasaram and GSS Banjari , its restoration became a top priority to prevent prolonged power outages 2. Fault Identification and Patrolling: After the tripping, line patrolling was conducted on the morning of 24th July 2021 . During the inspection, it was discovered that the B-phase conductor had snapped and damaged both the 33KV and 11KV feeders. This damage occurred between location number 01 and the gantry at GSS Sasaram . The patrolling team confirmed that a comple te replacement of the damaged conductor was necessary to restore the line.

15. 3. Restoration Process: To ensure the uninterrupted power supply to GSS Sasaram and GSS Banjari , the restoration was treated with the highest urgency . Now that the problem was identified, it was urgent to fix it and restore power . The following steps were taken to fix the line : The restoration steps included : Removing the damaged section of the B-phase conductor. Lowering the disc insulator string to make necessary repairs. Jointing the damaged section of the conductor with a new one. Jointing the disc insulator string with the new conductor. Uploading the conductor between the span of the GSS Sasaram gantry and the dead-end tower . Despite the challenges posed by the weather, the team completed the restoration on the same day.

16. Tower Protection Tower Protection to Prevent Soil Erosion To prevent soil erosion at riverbanks near towers, specific protective measures are required . These measures are typically temporary and designed for the monsoon season. They include the use of bamboo piling, stacking empty cement (EC) bags in nylon crates (NCs), laying geo bags , or stacking geo bags in gabions (1.8m x 1.8m x 0.5m). The design of these protection methods depends on the actual site conditions, which may vary based on factors such as river depth, water flow patterns, soil erosion characteristics, and the direction of the river. The protection strategy generally involves two key components: creating studs and constructing a slope at the river embankment near the tower. Studs: Purpose: Studs are placed upstream of the river to redirect water flow away from the tower. Construction : They consist of a staircase-like structure made from layers of NCs or gabions . This method is particularly useful in large rivers with heavy water discharge . The number of studs needed is determined by the specific site conditions.

17. Continued ... 2. Slope Protection: Purpose : To prevent further soil erosion near the tower at the river embankment . Procedure : 1. Excavation: Excavate the riverbank to create a slope with the appropriate angle . 2 . Bamboo Piling: Install bamboo piles in two layers at the base of the slope using water jets. The depth of the bamboo piling depends on the site conditions . 3. NC Layering: Place layers of NCs between the two layers of bamboo piles. Each NC (1m x 1m x 1m ) contains 25 EC bags . 4 . Geo Bags: Lay geo bags over the slope to prevent erosion. The geo bags are supported by the layers of bamboo piling and NCs. Emergency Measures : If the river water level is exceptionally high and there is an immediate threat to the tower due to severe erosion, bamboo piling may not be feasible. In such cases, protection is achieved using only NCs and gabions. These are stacked near the tower to fill the voids created by erosion and provide immediate reinforcement.

18. Bamboo Piling