Maintenance

Electrical close and trip check (control power required)

A check of the circuit-breaker control circuits is performed while the unit is still connected to the switchgear by the split- plug jumper. This check is made with the circuit breaker energized by control power from the switchgear.

1.Once the circuit-breaker springs are CHARGED, move the switchgear- mounted close/trip switch to the CLOSE position. There should be both the sound of the circuit breaker closing and indication the circuit-breaker contacts are CLOSED by the main contact status indicator.

2.As soon as the circuit breaker has closed, the automatic spring-charging process is repeated.

3.After a satisfactory close operation is verified, move the switchgear-mounted close/trip switch to the TRIP position, or send a trip command from a protective relay. Verify by both sound and contact position that the contacts are OPEN. Completion of these checks demonstrates satisfactory operation of auxiliary switches, internal protective relays and solenoids.

Spring-charging motor checks

No additional checks of the spring- charging motor are necessary.

Vacuum interrupter

The life expectancy of a vacuum interrupter is a function of the number of interruptions and magnitude of current interrupted.

A vacuum interrupter must also be replaced at 10,000 mechanical operations or when the contacts have been eroded beyond allowed limits.

Vacuum interrupter replacement procedures are detailed in the following maintenance instructions.

The curve shown in Figure 41: Typical vacuum interrupter contact curve on page 48 is offered as a guide to life expectancy.

Vacuum-interrupter mechanical check

Refer to Figure 42: Lower pole support

with insulated coupler, Figure 43: Primary contact CLOSED and insulated coupler DISCONNECTED and Figure 44: CLOSED primary contact forced OPEN by manual pressure on page 49, Figure 45: Contact- resistance test of the primary contacts on page 52 and Figure 46: Vacuum interrupter replacement illustration on page 56.

Before putting the circuit breaker into service, or if a vacuum interrupter is suspected of leaking as a result of mechanical damage, perform a vacuum- integrity check either mechanically as described in this section, or alternatively, electrically using a high-potential test set as described in the next section.

Open and isolate the circuit breaker and detach the insulated coupler (48.0) from lever (48.6) (refer to Figure 42: Lower pole support with insulated coupler).

The atmospheric pressure will force the moving contact of a hermetically-sealed interrupter into the CLOSED position, causing lever (48.6) to move into the position shown in Figure 43: Primary contact CLOSED and insulated coupler

DISCONNECTED.

A vacuum interrupter may be assumed to be intact if it shows the following characteristics:

1.An appreciable closing force has to be overcome when lever (48.6) is moved to the OPEN position by hand (refer to Figure 44: CLOSED primary contact forced OPEN by manual pressure).

2.When the lever is released, it must automatically return to the CLOSED position with an audible sound as the contacts touch.

After vacuum-integrity check, reconnect the lever (48.6) to the insulated coupler (48.0).

48.648.0

Figure 42: Lower pole support with insulated coupler

48.6

48.0

Figure 43: Primary contact CLOSED and insulated coupler DISCONNECTED

Figure 44: CLOSED primary contact forced OPEN by manual pressure

49

Page 48 Page 50
Page 49
Image 49
Siemens 38-3AH3 38 kV instruction manual Spring-charging motor checks, Vacuum-interrupter mechanical check
Page 48 Page 50

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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