Main Power Bus
400 V DC Primary Distribution Bus
The 400 V DC primary distribution bus is an 80-kilogram electrical backbone that routes full reactor and solar generation to high-power consumers across the Lunar Ark. Constructed with tinned copper bus bars on alumina high-voltage standoffs inside a 316L stainless steel enclosure, the system operates as a redundant A+B dual bus rated at 400 amperes. Operating at 400 volts DC reduces resistive transmission losses over long runs compared to legacy 28-volt or 120-volt systems while directly matching energy storage battery rack voltages. In the lunar vacuum, the absence of air ionization eliminates atmospheric arcing, while integrated bus-tie contactors manage load transfer during electrical faults.
400 V DC main distribution bus carrying full reactor/solar output to high-power consumers across the Ark.
Purpose
400 V DC main distribution bus carrying full reactor/solar output to high-power consumers across the Ark.
Context
Child of L2-PDM-BUS within the Lunar Ark system
Principles
- ▸High-voltage DC (400 V) reduces I^2R losses vs 28/120 V over long runs
- ▸Bus regulation via central converter or distributed sources
- ▸Dual-bus topology (A + B) for redundancy
- ▸Bus-tie contactors enable load transfer during fault
- ▸Hardware over-voltage trip protects connected equipment
Typical implementations
- ▸ISS 160 V solar / 120 V distribution heritage
- ▸NASA developing 120/400 V DC architectures for lunar surface
- ▸Vicor 100-400 V high-density DC-DC for new space
Lunar considerations
- ▸High-voltage DC well-suited to vacuum (no air ionization)
- ▸Lightning/arc protection not needed (no atmosphere)
- ▸Bus voltage chosen to match ESS battery rack voltage (~400 V)
Specifications
Functional
| primary function | 400 V DC main distribution bus carrying full reactor/solar output to high-power consumers across the Ark. |
| bus voltage v | 400 |
| rated current a | 400 |
| redundancy | A+B dual bus |
Physical
| mass kg | 80 |
| materials | Tinned Cu bus bars, Alumina HV standoffs, 316L SS enclosure |
| vacuum compatibility | True |
Operational
| power consumption w | 0 |
| thermal range c | -40, 70 |
| lifetime years | 50 |
| mtbf hours | 500000 |
Interfaces
Provides
- Primary 400 V supply to all loads
Requires
- Reactor/solar source
- Battery support
- Transient buffering
Cite this entry
Lunar Ark Codex. "Main Power Bus" (L3-PDM-BUS-MAIN). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-PDM-BUS-MAIN
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.