Vacuum interrupter/ operator

Trip-free interlock

Figure 32: Circuit-breaker interlocks and ground disconnect on page 33 shows the devices providing the trip-free interlock function. The purpose of the trip-free interlock is to hold the circuit breaker operating-mechanism mechanically and electrically trip-free. The circuit breaker is held trip-free during racking and whenever the circuit breaker is between the TEST and CONNECT positions within the switchgear enclosure.

This interlock functions so that the circuit breaker primary contacts can only be closed when in the CONNECT position, in the TEST position or out of the switchgear cell.

Rating interlock

Figure 32: Circuit-breaker interlocks and ground disconnect on page 33 shows the rating-interlock interference plates mounted on the circuit- breaker frame. The circuit-breaker interference plates are complemented by matching plates located in the cubicle.

The interference plates (rating interlocks) test the circuit-breaker voltage, continuous current and interrupting and momentary ratings and will not allow circuit breaker insertion unless the circuit-breaker ratings match or exceed the cell rating.

Circuit-breaker frame

The frame of the type 38-3AH3 vacuum circuit breaker contains several important devices and features deserving of special attention. These are the ground disconnect, the four racking wheels and the four handling wheels.

Ground disconnect

Figure 32: Circuit-breaker interlocks and ground disconnect on page 33 shows the ground disconnect contact mounted at the bottom of the circuit breaker. The spring- loaded fingers of the disconnect contact engage the ground bar (refer to Figure 33: Circuit-breaker compartment (MOC/TOC switch cover removed for photo) on page

34)at the bottom of the switchgear assembly. The ground bar is to the right of the racking mechanism, shown at the bottom center of the switchgear.

Circuit-breaker handling wheels

The type 38-3AH3 vacuum circuit breaker is designed for easy movement into and out of the metal-clad switchgear assembly. A section of indoor or Shelter-Clad switchgear does not require a transfer truck or lifting truck for handling of the circuit breaker when all circuit breakers are located at floor level. Once the circuit breaker is racked out of the switchgear, the unit can be pulled using the handles on the front of the circuit breaker. The circuit breaker will roll on its bottom four wheels.

Hazardous voltage and high-speed moving parts.

Will cause death, serious injury and property damage.

Do not by-pass interlocks or otherwise make interlocks inoperative. Interlocks must be in operation at all times.

Read this instruction manual. Know and understand correct interlock function. Check interlock function prior to inserting a circuit breaker into a switchgear cubicle.

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Siemens 38-3AH3 38 kV instruction manual Trip-free interlock, Rating interlock, Circuit-breaker frame, Ground disconnect
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38-3AH3 38 kV specifications

The Siemens 38-3AH3 is a high-voltage circuit breaker designed for medium voltage applications, particularly in substations and industrial environments. This device operates at a voltage level of 38 kV, showcasing Siemens' commitment to innovation and reliability in electrical engineering.

One of the main features of the Siemens 38-3AH3 is its advanced interruption technology, which employs the proven hybrid design combining both gas-insulated and air-insulated technologies. This hybrid approach not only enhances the breaker's performance and reliability but also minimizes its footprint, making it an ideal choice for space-constrained environments.

The Siemens 38-3AH3 uses vacuum interruption technology, allowing for efficient switching with minimal wear and tear. The vacuum interrupters are highly reliable and provide excellent performance under various operating conditions. This technology ensures that the circuit breaker can handle short circuits and overloads effectively, thus protecting the entire electrical system.

Additionally, the Siemens 38-3AH3 incorporates intelligent monitoring systems. These digital technologies provide real-time data on breaker status, operational performance, and maintenance needs. This predictive maintenance capability helps operators to identify potential issues before they develop into significant problems, ultimately leading to reduced downtime and maintenance costs.

Another notable characteristic of the Siemens 38-3AH3 is its high insulation strength. Thanks to its robust design and development, this circuit breaker can withstand adverse environmental conditions, making it suitable for use in diverse geographical locations and climates. Its components are designed to resist contamination and corrosion, ensuring long-term reliability.

The Siemens 38-3AH3 also offers enhanced safety features. It includes protective relays and automatic fault detection systems that isolate faults quickly, preventing damage to downstream equipment. Furthermore, the design allows for easy maintenance, with components that are accessible without the need for extensive disassembly.

In summary, the Siemens 38-3AH3 38 kV circuit breaker is a leading solution in high-voltage protection and control, characterized by its advanced interruption technology, integrated monitoring systems, high insulation strength, and user-friendly maintenance features. Its innovative design and engineering make it a trusted choice for utilities and industrial facilities aiming to enhance the reliability and safety of their electrical systems.
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