53.0- Manual close button
54.0- Manual open (trip) button
55.0- CHARGED/DISCHARGED indicator
58.0- OPEN/CLOSED indicator
59.0- Operations counter
Figure 13: Operating mechanism controls and indicators
The OPEN/CLOSED indicator (58.0), CHARGED/DISCHARGED indicator (55.0) and the operations counter (59.0) are located on the front of the mechanism housing (60.0).
Circuit-breaker pole
Refer to Figure 14: Type 38-3AH3 vacuum circuit breaker pole section on page 19. The vacuum interrupter (30.0) is rigidly connected to the upper terminal and pole support (20.0) by its terminal bolt (31.2). The lower part of the vacuum interrupter is stabilized against lateral forces by a centering ring (28.1) on the pole-support (40.0). The external forces due to switching operations and the contact pressure are absorbed by the struts (28.0).
Current-path assembly
Refer to Figure 14: Type 38-3AH3 vacuum circuit breaker pole section on page 19. The current-path assembly consists of the upper terminal and pole support (20.0), the stationary contact (31.0) and the moving contact (36.0), that is connected with the lower terminal (29.0) by terminal clamp (29.2) and a flexible shunt (29.1).
Vacuum interrupter
Refer to Figure 9: Vacuum interrupter cutaway view on page 15. The moving- contact (36.0) motion is aligned and stabilized by guide bushing (35.0). The metal bellows (34.0) follows the travel of contact (36.0) and seals the vacuum interrupter against the surrounding atmosphere.
Switching operation
Refer to Figure 14: Type 38-3AH3 vacuum circuit breaker pole section on page 19. When a closing command is initiated, the closing spring, that was previously charged by hand or by the motor, actuates the moving contact (36.0) through jack shaft (63.0), lever (63.7), insulated coupler (48.0) and lever (48.6).
The motion of the insulated coupler is converted into the vertical movement of the moving contact.
The moving-contact motion is controlled by the guide link (48.9), that pivots on support (40.0) and the eye bolt (36.3).
During closing, the tripping spring and the contact-pressure springs (49.0) are charged and latched by the pawl (64.1). The closing spring is recharged immediately after closing.
In the CLOSED state, the necessary contact pressure is maintained by the contact- pressure spring and the atmospheric pressure. The contact-pressure spring automatically compensates for contact erosion, which is very small.
