The Terasaki XS800ss XS Series represents a specific and advanced configuration within the XS800 line.
The designation breaks down as follows:
• XS800: 800A frame size.
• s: Withdrawable (Slide-out) version.
• s: Equipped with the S-Type Electronic Trip Relay.
So, the XS800ss is a Withdrawable Air Circuit Breaker with a Standard S-Type Trip Unit.
Detailed Overview of the Terasaki XS800ss
This model combines the critical operational feature of a withdrawable design with the advanced protection of the standard S-type trip unit. It is a very common configuration for main distribution breakers where both serviceability and reliable protection are required.
Key Features and Highlights
1. Withdrawable Design (The First 's'):
◦ This is the defining physical characteristic. The entire breaker is mounted on a removable chassis that can be racked into a fixed frame within the switchboard.
◦ It features three key, interlocked positions:
■ CONNECTED: The breaker is fully engaged, and both primary and secondary contacts are made.
■ TEST: The main power contacts are isolated, but the control wiring remains connected. This allows for safe testing of the protection functions (e.g., trip simulations) and control circuits without energizing the downstream load.
■ DISCONNECTED: The breaker is fully withdrawn and isolated from both the main busbars and the load terminals, creating a visible air gap for safe maintenance.
◦ Primary Advantage: Allows for easy maintenance, replacement, and electrical testing without needing to de-energize the entire main switchboard, drastically reducing system downtime.
2. S-Type Electronic Trip Unit (The Second 's'):
◦ This is the core of its intelligent protection. The "S-Type" ETR provides fully adjustable and precise protection settings:
■ Long-Time Delay (L): For protection against sustained overloads. Adjustable current (Ir) and time delay.
■ Short-Time Delay (S): For selective short-circuit protection. Adjustable current (Isd) and time delay, with an I²t IN/OUT function for optimal coordination with downstream breakers.
■ Instantaneous (I): For high-level short-circuits. Adjustable current setting (Ii).
■ Ground-Fault (G): For protection against earth leakage currents. Adjustable current (Ig) and time delay.
3. Standard Breaking Capacity:
◦ The "ss" model typically has the standard breaking capacity (as opposed to the "hs" which has a high breaking capacity).
◦ Its Ultimate Breaking Capacity (Icu) is still very robust, typically in the range of 50kA to 65kA at 415V (exact values must be confirmed from the specific datasheet). This is suitable for the vast majority of main and sub-main distribution applications.
4. Communication Ready:
◦ The S-Type trip unit is almost always prepared for an optional communication module (e.g., Terasaki's TML-CM or standard protocols like Modbus RTU).
◦ This allows for integration into Building Management Systems (BMS) or SCADA for:
■ Remote monitoring (current, voltage, power, energy, status).
■ Remote control (open/close).
■ Alarm and event logging.
Technical Specifications (Typical)
Feature
Specification
Frame Size
800A
Rated Current (Iu)
Adjustable via S-type ETR, typically from 400A to 800A.
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
Comparison within the XS800 Family
To clarify its position, here's a quick comparison:
Model
Type
Breaking Capacity
Trip Unit
Typical Use Case
XS800ns
Fixed
Standard
S-Type
Feeder/protection where easy removal isn't critical.
XS800ss
Withdrawable
Standard
S-Type
Main/Sub-main where serviceability is key.
XS800hs
Withdrawable
High
S-Type
Main incomer in systems with very high available fault current.
Common Applications
The XS800ss is ideally suited for:
• Main Incomer Breakers: In medium-sized industrial plants, commercial buildings, and hospitals where the available fault current is within its standard range and maintenance is a priority.
• Sub-Main Distribution: Protecting large feeders or transformers.
• Marine & Offshore: A very popular choice for shipboard main switchboards, where the withdrawable feature is essential for maintenance at sea and the S-type unit provides precise protection for generators and distribution.
• Any critical circuit that requires the ability to be quickly isolated and removed for testing or replacement without shutting down the entire switchboard.
Summary
The Terasaki XS800ss is a highly versatile and practical air circuit breaker. It strikes an excellent balance between advanced electronic protection (S-Type) and superior serviceability (Withdrawable). It is the go-to choice for engineers who need a reliable, maintainable, and intelligent circuit breaker for main distribution duties where the highest levels of fault current are not present.