Which voltage is typical for DC traction in metro systems?

Which voltage is typical for DC traction in metro systems?

• A. 25 kV AC
• B. 750 V DC
• C. 1500 V DC
• D. 12 V DC

Answer: (B)

DC traction power for metro systems is typically supplied at 750 V DC. This voltage level strikes a practical balance between delivering enough current for strong acceleration and keeping insulation, safety, and infrastructure costs manageable in tight, underground environments. The 750 V DC standard supports common metro configurations like third-rail or overhead systems while allowing compact traction equipment and simpler power electronics. Higher voltages, such as 25 kV AC, are more common on mainline railways with longer spans and higher power needs, which aren’t typical for dense urban metros. Very low voltages like 12 V DC serve only auxiliary onboard systems, not traction. Some networks do run higher DC voltages, such as 1500 V DC, but 750 V DC remains the most widely adopted standard for metro traction.

DC traction power for metro systems is typically supplied at 750 V DC. This voltage level strikes a practical balance between delivering enough current for strong acceleration and keeping insulation, safety, and infrastructure costs manageable in tight, underground environments. The 750 V DC standard supports common metro configurations like third-rail or overhead systems while allowing compact traction equipment and simpler power electronics. Higher voltages, such as 25 kV AC, are more common on mainline railways with longer spans and higher power needs, which aren’t typical for dense urban metros. Very low voltages like 12 V DC serve only auxiliary onboard systems, not traction. Some networks do run higher DC voltages, such as 1500 V DC, but 750 V DC remains the most widely adopted standard for metro traction.