L2-PDM-BUS CRITICAL POWER ENERGY Level 2 · hardware

Power Bus Architecture

Multi-Tier Power Bus Distribution Network

The multi-tier power bus distribution network is a physical distribution backbone that routes electrical power across settlement subsystems using silver-plated copper bus bars segregated into main, critical, and auxiliary tiers. Regulating line voltage at 120 V DC within ±2% and incorporating cross-tie switching, the architecture isolates life-safety and archive loads from auxiliary faults. Sustaining this network in the lunar environment requires managing conductor thermal expansion across 300 K temperature swings, utilizing vacuum-rated polyimide insulation to prevent corona discharge, sealing junction boxes against dust infiltration, and mitigating radiation degradation on bus voltage regulators over a 100-year operational lifetime.

Multi-tier power bus architecture comprising main bus, critical bus, and auxiliary bus segments for structured power distribution across all Ark subsystems.

Purpose

Provides the physical and logical backbone for power distribution, segregating loads by criticality tier to ensure life-critical and archive-critical systems always receive power.

Context

Forms the central spine of the L1-PDM system; all other PDM subsystems (switching, protection, monitoring, harness) connect to and serve the bus architecture.

Principles

▸Tiered bus architecture isolates critical loads from non-essential load faults
▸Cross-tie switches allow bus reconfiguration under failure scenarios
▸Voltage regulation at bus level minimizes downstream converter complexity
▸Bus impedance must be controlled to prevent voltage droop at end-of-line loads

Typical implementations

▸Main bus: 120V DC high-power backbone for primary loads
▸Critical bus: Independently fed bus for life-safety and archive systems
▸Auxiliary bus: Lower-priority loads that can be shed first
▸Cross-tie contactors between bus segments for reconfiguration
▸ISS-heritage 120V DC primary bus architecture

Lunar considerations

▸Bus bar thermal expansion under 300K temperature swings
▸Vacuum-rated insulation to prevent corona discharge
▸Dust-sealed bus bar connections at junction points
▸Radiation effects on bus voltage regulators over 100 years

Specifications

Functional

primary function	Provide structured multi-tier power bus network segregating loads by criticality level
inputs	Conditioned DC power from generation and storage sources
outputs	Regulated bus power at main, critical, and auxiliary tiers
main bus voltage vdc	120
voltage regulation percent	+/- 2
bus segments	minimum 3 tiers (main, critical, auxiliary)
cross tie capability	True

Physical

materials	Silver-plated copper bus bars, Vacuum-rated polyimide insulation, Hermetically sealed junction boxes
vacuum	True
radiation tolerant	True

Operational

thermal range c	-173, 127
lifetime years	100

Interfaces

Provides

→Switching & Relay GearBus segments for switchingcritical
Provides bus segment endpoints for cross-tie and isolation switching
→Distribution Wiring HarnessBus connection pointscritical
Provides physical attachment points for distribution harness runs

Requires

←Power Generation SystemGenerated powercritical
Receives conditioned DC power from generation subsystem
←Energy Storage SystemsStored powercritical
Receives backup power from energy storage during shortfalls