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Terasaki XS250ns XS Series air circuit breakers marine power systems

Terasaki XS250ns XS Series air circuit breakers marine power systems

  • Product Item : XS250ns
  • Product Brand : Terasaki
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The Terasaki XS250ns is a specific model within the highly respected Terasaki XS Series of Air Circuit Breakers (ACBs), and its application in marine power systems is a primary and critical use case.

Here is a detailed breakdown of the Terasaki XS250ns and its role in marine electrical systems.

Overview: Terasaki XS Series

Terasaki Electric Co., Ltd. (now part of the Mitsubishi Electric group) is renowned for manufacturing robust and reliable electrical switchgear, with a strong reputation in the marine industry. The XS Series represents their modern line of ACBs designed for high performance, safety, and durability.

Key General Features of the XS Series:

Advanced Protection Relays (ETU): The brain of the breaker is its Electronic Trip Unit (ETU). It provides precise protection against:

Overload (Long-Time Delay): Protects cables from overheating.

Short-Circuit (Short-Time Delay): Selectively isolates faults.

Instantaneous Trip: For very high-level fault currents.

Ground Fault (Earth Leakage): Critical for personnel and equipment safety.

Current Limiting Design: The XS series is designed to interrupt a fault extremely quickly (within milliseconds), limiting the let-through energy (I²t) and minimizing damage to downstream equipment.

Robust Construction: Built to withstand the harsh conditions of a marine environment, including vibration, shock, humidity, and salt-laden air.

Communications Capability: Many models can be equipped with communication modules (e.g., Modbus, Profibus) for integration into a ship's power management system (PMS).

Deep Dive: XS250ns Model

The "XS250ns" model number breaks down as follows:

XS: Series name.

250: The frame size, indicating a rated current of up to 2500 Amps. (Note: The actual continuous current rating is set by the installed rating plug).

ns: This suffix typically indicates a specific performance level or a non-standard configuration, often related to its high breaking capacity. It signifies a breaker with an extremely high Icu (Ultimate Breaking Capacity) and Ics (Service Breaking Capacity), crucial for handling the massive fault currents possible in large shipboard power systems.

Key Specifications (Typical for XS250ns):

Rated Current (Iu): Up to 2500A (set via rating plug).

Rated Operational Voltage (Ue): Typically 690V AC or higher, suitable for marine HV systems.

Breaking Capacity (Icu/Ics): Very high, often in the range of 100kA to 150kA (at 415/440V), which is essential for main switchboards.

Tripping Unit: Equipped with a sophisticated ETU (e.g., M- or P-type) offering adjustable protection settings.

Application in Marine Power Systems

On a ship, the Terasaki XS250ns is not a small component; it's a major piece of primary distribution equipment. You would typically find it in the Main Switchboard (MSB).

Its primary roles are:

Main Generator Protection:

It is directly connected to the output of a large ship's generator (e.g., a 2-3 MW generator).

It protects the generator itself from damage due to overloads and internal faults.

It protects the cables connecting the generator to the MSB.

Bus Tie Breaker:

Ships often have multiple generators and multiple sections of the main switchboard.

An XS250ns can be used as a "bus tie" or "sectionalizing" breaker to connect these sections.

It allows for load sharing between generators and provides redundancy. If one generator fails, the bus tie can close to feed power from the healthy section.

Primary Feeder Protection:

It can protect large, centralized loads like the Propulsion Motor Drive (if not a dedicated system), large bow thrusters, or heavy cargo-handling equipment.

Why Terasaki XS Series is Preferred in Marine Environments

Marine Certification: Terasaki breakers are built to meet and exceed major marine classification society standards such as:

Lloyd's Register (LR)

Det Norske Veritas (DNV)

American Bureau of Shipping (ABS)

Bureau Veritas (BV)

This certification is mandatory for equipment used in critical shipboard applications.

Corrosion Resistance: The breakers are treated with special coatings and paints designed to resist corrosion from saltwater atmospheres.

Vibration and Shock Resistance: The mechanical and electrical components are designed to remain operational despite the constant vibration and potential shock (e.g., from heavy seas) experienced on a vessel.

High Reliability: In a ship at sea, there is no "backup grid." The electrical system must be reliable. Terasaki's reputation for robust and dependable operation is paramount.

Selective Coordination: The adjustable trip settings on the ETU allow system designers to coordinate the XS250ns with downstream breakers (e.g., molded case circuit breakers - MCCBs). This ensures that in the event of a fault, only the breaker closest to the fault trips, isolating the problem without blacking out non-essential loads.

Comparison with Other Brands

In the marine world, Terasaki competes directly with other major brands like:

Siemens (3WL)

ABB (Emax)

Schneider Electric (Masterpact)

Mitsubishi Electric (AE-SW)

Terasaki often holds a strong market position due to its long-standing heritage, specialized marine focus, and perceived mechanical ruggedness.

Summary

The Terasaki XS250ns is a high-capacity, extremely robust air circuit breaker engineered for the most demanding applications, with marine power systems being a core market. Its role is to act as a guardian for the heart of the ship's electrical network—protecting generators, managing power distribution, and ensuring the overall safety and integrity of the system with its high breaking capacity and advanced, adjustable protection features.