UniGear ZS1 200A 440V

Common issues

• Loose busbar or cable lug connections leading to hot spots and increased contact resistance
• Circuit breaker contact wear/pitting from repeated interruption of load or fault current
• Protection relay settings drifting out of coordination with the main switchboard over time
• Insulation degradation from moisture/condensation ingress in the machinery space
• Automatic changeover/failure-to-start logic not correctly re-tested after emergency generator work
• Indicator lamp or instrument transformer failure giving false status readings
• Terminal corrosion in a humid engine room or emergency generator room environment

Inspection checklist

• Thermographic (IR) scan of busbars, breaker connections and cable terminations under load
• Verify emergency generator auto-start and auto-changeover sequence and timing against the SOLAS requirement
• Test circuit breaker trip functions (overcurrent, short circuit, undervoltage where fitted)
• Check insulation resistance of busbars and feeder cables
• Verify protection relay settings against the vessel's approved discrimination/selectivity study
• Inspect enclosure seals/gaskets and IP rating integrity, especially in a wet space
• Check busbar and cable connection tightness/torque per the maker's schedule
• Confirm emergency lighting and alarm circuits fed from the board function correctly
• Verify labelling and the single-line diagram at the board match the as-built condition

Service intervals

Critical spares

• Circuit breaker matching the board's frame and rating
• Protection relay unit
• Indicator lamps and control switches
• Fuses matching the board rating
• Auxiliary/control contactors for the changeover logic

Safety

• Arc flash hazard when working live or racking breakers - use appropriate PPE and follow lockout/tagout
• Stored energy in spring-charged breaker mechanisms - discharge before maintenance
• The emergency switchboard is normally live at all times from the emergency source - never assume it is dead because the main board is isolated
• Condensation/moisture ingress raises shock risk in humid compartments

Class survey

Emergency switchboards are checked at annual survey for correct labelling, insulation resistance and correct function of the automatic changeover/emergency generator start sequence; class wants records of the blackout test demonstrating emergency power restoration within the required time.