The Terasaki XS400ss XS Series is a highly versatile and widely used air circuit breaker, particularly in applications where serviceability and precise protection are key.
Here is a detailed overview.
Model Designation Breakdown: XS400ss
XS400: 400 Ampere frame size.
First 's': Withdrawable or Slide-out version.
Second 's': Equipped with the standard S-Type Electronic Trip Relay.
In essence, the XS400ss is a 400A, withdrawable air circuit breaker with an intelligent S-Type trip unit and a standard breaking capacity.
Key Features and Highlights
Withdrawable Design (The First 's'):
This is a critical feature for operational flexibility and safety. The entire breaker is mounted on a removable chassis that can be racked in and out of its fixed mounting frame.
It provides three distinct, interlocked positions:
CONNECTED: Fully engaged with both power and control circuits.
TEST: Main power contacts are isolated, but control wiring remains live. This allows for safe testing of protection functions and control schemes without energizing the downstream load.
DISCONNECTED: The breaker is fully withdrawn, creating a visible air gap for safe maintenance and replacement.
Primary Advantage: Enables rapid isolation, testing, and replacement without shutting down the entire switchboard, minimizing system downtime.
S-Type Electronic Trip Unit (The Second 's'):
This is the "brain" of the breaker, providing fully adjustable and selective protection.
Long-Time Delay (L): Protects against sustained overloads. Adjustable for current (Ir) and time.
Short-Time Delay (S): Protects against short-circuits, with an adjustable current (Isd) and time delay. The I²t IN/OUT function allows for optimal coordination with downstream devices.
Instantaneous (I): For very high-level short-circuits. Adjustable current setting (Ii).
Ground-Fault (G): Provides sensitive protection against earth leakage currents. Adjustable for current (Ig) and time delay.
Standard Breaking Capacity:
The "ss" model has a standard breaking capacity, which is robust and suitable for the majority of applications. Its Ultimate Breaking Capacity (Icu) is typically in the range of 50kA to 65kA at 415V (exact values must be confirmed from the specific datasheet).
This distinguishes it from the "hs" (High-breaking capacity) version, which is designed for systems with extremely high available fault current.
Communication Capability:
The S-Type trip unit is typically prepared for an optional communication module (e.g., Modbus, Terasaki TML-CM).
This enables integration into Building Management Systems (BMS) or SCADA for remote monitoring (current, power, energy, status), control, and event logging.
Technical Specifications (Typical)
Feature Specification
Frame Size 400A
Rated Current (Iu) Adjustable via S-type ETR, e.g., from 200A to 400A.
Rated Operational Voltage (Ue) 690V AC
Breaking Capacity (Icu) Standard - e.g., 65kA at 415V AC (Confirm with datasheet).
Trip Unit Electronic (S-Type)
Type Withdrawable
Standard IEC 60947-2