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

Protection & Fault Isolation

Overcurrent, Ground Fault, and Arc Detection Protection System

The overcurrent, ground fault, and arc detection protection system is an electrical safety layer that continuously monitors distribution circuits to isolate faults before damage propagates across the network. The lunar environment introduces severe failure mechanisms: the vacuum eliminates the atmospheric quenching that naturally suppresses electrical arcs, surface dust contamination creates leakage paths that induce ground faults, and radiation-induced latchup in semiconductor electronics can mimic overcurrent faults. Constructed with radiation-hardened analog comparators and high-bandwidth current transformers, the system senses ground faults down to 100 mA, clears overcurrent faults in under 1 ms, and isolates vacuum arc faults within 10 ms, maintaining a false trip rate below once per year across a 100-year design lifetime.

Protection system providing overcurrent detection, ground fault isolation, and arc fault detection to prevent cascading failures in the power distribution network.

Purpose

Detects and isolates electrical faults within milliseconds to prevent damage propagation, bus collapse, and loss of critical systems.

Context

Operates as a safety layer across the entire L1-PDM system, monitoring bus and load circuits through L2-PDM-MON sensors and commanding L2-PDM-SWGR to isolate faulted segments.

Principles

▸Protection must be faster than fault propagation time
▸Selective coordination ensures only the faulted segment is isolated
▸Multiple protection layers provide defense in depth
▸Arc faults in vacuum behave differently than in atmosphere and require specialized detection

Typical implementations

▸Current-limiting solid-state power controllers with built-in trip thresholds
▸Ground fault detection via differential current sensing
▸Arc fault detection using high-frequency current signature analysis
▸Coordinated protection zones with time-graded selectivity
▸Hardware watchdog timers for protection system self-monitoring

Lunar considerations

▸Vacuum arc behavior differs from atmospheric arcing
▸No atmospheric quenching of arc faults
▸Lunar dust contamination can create leakage paths causing ground faults
▸Radiation-induced latchup in semiconductors can mimic overcurrent faults
▸Self-healing after transient faults must be automatic

Specifications

Functional

primary function	Detect and isolate overcurrent, ground fault, and arc fault conditions to prevent cascading power system failures
inputs	Current and voltage measurements from L2-PDM-MON, High-frequency current waveforms for arc detection
outputs	Fault isolation commands to L2-PDM-SWGR, Fault event logs to L1-CDH, Alarm signals to L2-PDM-MON
overcurrent trip time ms	<1
ground fault detection sensitivity ma	100
arc fault detection time ms	<10
false trip rate	<1 per year

Physical

materials	Radiation-hardened analog comparators, High-bandwidth current transformers, Shielded signal cabling
vacuum	True
radiation tolerant	True

Operational

thermal range c	-173, 127
lifetime years	100

Interfaces

Provides

→Switching & Relay GearFault isolation commandscritical
Issues emergency switch-open commands to isolate faulted bus segments or loads
→Command & Data HandlingFault event dataessential
Reports fault type, location, magnitude, and isolation actions taken

Requires

←Power Monitoring & MeteringCurrent and voltage measurementscritical
Receives real-time electrical measurements for fault detection algorithms
←Power Bus ArchitectureBus topology informationessential
Knows bus configuration for selective coordination of protection zones