Terasaki XS400hs in a Nutshell
• XS400: 400 Ampere frame size.
• h: High Breaking Capacity. Designed to interrupt very high fault currents.
• s: Withdrawable (Slide-out) version. Essential for maintenance and safety.
This breaker is a compact, high-performance, and intelligent device used for main distribution and protection of large feeders on ships and offshore platforms.
Key Features & Why They Matter for Marine Systems
1. High Breaking Capacity ('h' Rating):
◦ Marine Significance: Marine electrical systems, especially those with large generators, have very high available fault currents. The XS400hs is engineered to safely interrupt these severe short-circuit faults (typical Icu can be 50kA, 65kA, or higher at 440V), protecting generators, switchboards, and cabling from catastrophic damage.
2. Withdrawable Design ('s' Version):
◦ Marine Significance: This is a critical feature for operational continuity and safety at sea.
■ CONNECTED, TEST, DISCONNECTED positions allow for safe functional testing of protection relays without energizing the main cables.
■ If a breaker fails or needs maintenance, it can be quickly isolated and replaced with a spare without de-energizing the entire main switchboard. This is vital for maintaining power to critical loads like navigation, steering, and firefighting systems.
3. Advanced S-Type Trip Unit:
◦ Marine Significance: Provides precise, adjustable protection that is crucial for system coordination (selectivity).
■ Long-Time Delay (L): Protects against generator/cable overload.
■ Short-Time Delay (S): Ensures selective tripping. A fault on a downstream feeder will cause that feeder breaker to trip first, without disconnecting the main breaker and blacking out the entire vessel.
■ Instantaneous (I): Provides rapid response for close-in major faults.
■ Ground-Fault (G): Extremely important for marine systems. Provides sensitive protection against earth leakage, enhancing safety against electric shock and fire in the confined, humid, and conductive environment of a ship. Marine classification societies have strict requirements for ground-fault protection.
4. Marine Environment Durability:
◦ Terasaki breakers are renowned for their robust construction.
◦ They are built with corrosion-resistant materials and coatings (e.g., stainless steel hardware, protected contacts) to withstand the salt-laden, humid marine atmosphere.
◦ They are designed to resist vibration and shock, which are ever-present on ships.
5. Communication and Monitoring:
◦ The S-Type trip unit is typically ready for an optional communication module (e.g., Modbus, Terasaki's TML-CM).
◦ Marine Significance: This enables integration into the ship's Integrated Monitoring and Alarm System (IMAS). Engineers can monitor real-time current, power, energy, and receive pre-trip alarms and event logs remotely from the control room, enabling predictive maintenance and quick diagnostics.
Typical Applications in Marine Power Systems
• Generator Breaker: Used as the primary breaker connecting a main generator to the main switchboard.
• Main Feeder Breaker: Protecting large distribution feeders to essential services like bow thrusters, large pump systems, or a secondary switchboard.
• Bus Tie Breaker: Connecting two sections of the main switchboard for redundancy and flexible operation.
• Large Motor Protection: For direct-on-line starting of large pumps, compressors, or hydraulic units.
Compliance with Marine Classification Societies
A critical aspect for any marine component is certification. Terasaki XS Series breakers are commonly type-approved by all major international marine classification societies, including:
• Lloyd's Register (LR)
• American Bureau of Shipping (ABS)
• Det Norske Veritas (DNV)
• Bureau Veritas (BV)
• ClassNK
This certification is not automatic; it signifies that the breaker has passed rigorous tests for performance, safety, and environmental resilience specific to marine use.
Why Terasaki is a Preferred Choice in Marine Engineering
• Reliability: Known for extremely low failure rates and high mechanical endurance.
• Selectivity: The advanced S-type trip unit allows for finely tuned protection schemes, preventing blackouts by isolating only the faulty section.
• Serviceability: The withdrawable design and global service network support quick maintenance and part availability in major ports worldwide.
• Proven Track Record: Terasaki has a long and established history as a trusted brand in the marine electrical sector.
The Terasaki XS400hs is not just an air circuit breaker; it is a core component of a safe, reliable, and redundant marine electrical power system. Its high breaking capacity, withdrawable design, intelligent protection features, and ruggedized construction make it an industry-standard choice for protecting vital assets on vessels ranging from cargo ships and tankers to passenger ferries and offshore support vessels.