Railway Electrification
Railway Electrifications – Indian Railways
Overview
Railway electrification is the backbone of IR’s energy-efficiency drive. 100% electrification is targeted by Dec-2023 (achieved 98.3% by Mar-2024). Work started in 1925 with 1.5 kV DC on Harbour line (Mumbai); today 83%+ of BG route-km runs on 25 kV/50 Hz single-phase AC.
Key Facts & Figures
| Fact | Detail |
|---|---|
| 1st electrified section | Mumbai Victoria Terminus – Kurla (Harbour line), 1925 |
| Present system | 25 kV / 50 Hz AC, single-phase, overhead catenary |
| Current-collection device | Pantograph (maximum 2 per loco) |
| Standard height of contact wire (BG) | 5.45 m above rail level (min 4.57 m) |
| Standard tension length | 1000 m ± 200 m |
| Catenary wire material | Cadmium-copper / High-strength copper / Al-Alloy |
| Return circuit for traction | Running rails & buried traction earth wire |
| Traction substation spacing | 50–80 km (ideally 72 km) |
| Power block duration for OHE maintenance | 4 h (00:00–04:00 hrs) |
| OHE span (normal) | 72 m (max permissible 81 m) |
| Regulating organization | CORE (Central Organization for Railway Electrification) – HQ Allahabad |
| CORE formed | 1971 |
| States with 100% BG electrification | Odisha, Andhra Pradesh, Telangana, Chhattisgarh, Jharkhand (as on 31-03-24) |
| Energy-neutral plan | 100% electrification + 30 GW solar target by 2030 |
| Energy-consumption norm | ≈ 6.5 kWh per 1000 GTKM for electric loco |
| Savings vs diesel | 33% energy + 25% maintenance cost |
| Record electrification in FY 23-24 | 6,565 RKM |
| Total electrified RKM (Mar-24) | 65,000 RKM out of 66,000 RKM BG network |
Important Points (Quick Revision)
- Only 25 kV AC system is adopted for all fresh electrification since 1957.
- DC sections (1.5 kV) around Mumbai converted to 25 kV AC in 2016–17.
- CORE is one of the six Production Units of Indian Railways.
- Rail-wheel return is bonded every 250 m to reduce rail potential.
- Neutral Section (dead zone) length: 41 m (5 insulators) on straight track.
- OHE is fed via 132/220 kV utility grid → 25 kV via 21.6 MVA traction transformer.
- Auto-transformer system (2 × 25 kV) used only in high-density routes (e.g., Bina–Katni).
- Electric locos have regenerative braking – energy fed back to grid (saves 15–30%).
- Wind speed limit for OHE maintenance: 40 kmph (gust 50 kmph).
- Web-creep in contact wire limited to 150 mm per 1000 m tension length.
- Minimum clearances: 4.29 m for goods-platform, 5.3 m for foot-over-bridge soffit.
- SCADA (Supervisory Control & Data Acquisition) controls all traction substations remotely.
- Railway declared 100% electrified on 31-12-23 except 1,100 km under gauge-conversion.
- All electric locos are fitted with HOG (Head-On-Generation) to power coaches (saves 4 crore L diesel/yr).
- Next target: 100% Head-On-Generation coaches & 3-phase IGBT propulsion.
Frequently Asked in Exams
- Full form & HQ of CORE.
- Voltage and frequency of OHE.
- Standard height of contact wire.
- Purpose of neutral section & its length.
- Energy savings due to regenerative braking.
Practice MCQs
Question:01 The present traction system adopted by Indian Railways is
A) 1.5 kV DC
B) 25 kV, 50 Hz AC
C) 15 kV, 16⅔ Hz AC
D) 750 V DC third rail
Show Answer
Correct Answer: B
Explanation: Indian Railways has standardised 25 kV, 50 Hz AC overhead electrification for its entire broad-gauge network, replacing older DC systems.
Question:02 CORE was set up in the year
A) 1957
B) 1967
C) 1971
D) 1981
Show Answer
Correct Answer: C
Explanation: The Central Organisation for Railway Electrification (CORE) was established in 1971 to spearhead railway electrification projects across India.
Question:03 The maximum spacing between two traction substations is generally
A) 40 km
B) 72 km
C) 100 km
D) 150 km
Show Answer
Correct Answer: B
Explanation: To limit voltage drop and ensure reliable 25 kV supply to locomotives, Indian Railways norms cap the distance between adjacent traction substations at about 72 km under normal loading conditions.
Question:04 Which of the following states was the first to achieve 100 % Broad-Gauge electrification of its railway network?
A) Odisha
B) Gujarat
C) Punjab
D) Kerala
Show Answer
Correct Answer: A
Explanation: Odisha became the first state in India to complete 100 % electrification of its entire Broad-Gauge railway network, a milestone achieved ahead of other states.
Question:05 The standard height of the contact wire above rail level for Broad Gauge (BG) is
A) 4.57 m
B) 5.45 m
C) 6.15 m
D) 7.0 m
Show Answer
Correct Answer: B
Explanation: As per Indian Railways standards, the minimum height of the contact wire above rail level for Broad Gauge is 5.45 m to ensure adequate electrical clearance and safe passage of rolling stock.
Question:06 Regenerative braking in electric locos feeds energy back to
A) Batteries
B) Auxiliary machines
C) Overhead equipment
D) Dynamic grids
Show Answer
Correct Answer: C
Explanation: During regenerative braking, the traction motors act as generators and return the recovered electrical energy to the 25 kV overhead catenary for use by other trains, instead of wasting it as heat.
Question:07 The length of a neutral section on straight track is
A) 21 m
B) 31 m
C) 41 m
D) 51 m
Show Answer
Correct Answer: C
Explanation: As per Indian Railways standards, the neutral section provided on straight track is 41 m long to ensure proper isolation of the 25 kV OHE supply.
Question:08 Which organization is responsible for Railway electrification in India?
A) RDSO
B) CORE
C) RITES
D) IRCTC
Show Answer
Correct Answer: B
Explanation: CORE (Central Organization for Railway Electrification) is the dedicated unit under Indian Railways entrusted with planning and executing railway-electrification projects across the country.
Question:09 The traction return circuit uses
A) Earth wire only
B) Rails and earth wire
C) Overhead earth wire only
D) 11 kV cable
Show Answer
Correct Answer: B
Explanation: In Indian Railways, the traction return current is deliberately shared between the running rails (which are bonded to form a low-resistance path) and a dedicated earth wire buried alongside the track. This dual path ensures low impedance, limits rail-to-earth potential, and provides redundancy, so option B is correct.
Question:10 100% electrification target (excluding GC sections) was officially achieved in
A) January 2022
B) December 2023
C) March 2025
D) December 2024
Show Answer
Correct Answer: B
Explanation: Indian Railways announced that 100% electrification of its broad-gauge network (excluding heritage/gauge-conversion sections) was completed in December 2023.
BETA
