Power Engineering Guide Transmission and Distribution (4)

Live-Tank Circuit-Breakers for 72 kV up to 800 kV

live tank C.B

The construction

All live-tank circuit-breakers are of the same general design, as shown in the illustrations.

They consist of the following main components:

1) Interrupter unit

2) Closing resistor (if applicable)

3) Operating mechanism

4) Insulator column (AIS)

5) Operating rod

6) Breaker base

7) Control unit

The uncomplicated design of the breakers and the use of many similar components, such as interrupter units, operating rods and control cabinets, ensure high reliability because the experience of many breakers in service has been applied in improvement of the design. The twin nozzle interrupter unit for example has proven its reliability in more than 60,000 units all over the world.

The control unit includes all necessary devices for circuit-breaker control and monitoring, such as:

_ Pressure/SF6 density monitors

_ Gauges for SF6 and hydraulic pressure (if applicable)

_ Relays for alarms and lockout

_ Antipumping devices

_ Operation counters (upon request)

_ Local breaker control (upon request)

_ Anticondensation heaters.

Transport, installation and commissioning are performed with expertise and efficiency. The tested circuit-breaker is shipped in the form of a small number of compact units. If desired, Siemens can provide appropriately qualified personnel for installation and commissioning.

Dead-Tank Circuit-Breakers for 72 kV up to 245 kV

Circuit-breakers in dead-tank design

Dead tank C.B

For certain substation designs, dead-tank circuit-breakers might be required instead of the standard live-tank breakers. For these purposes Siemens can offer the dead-tank circuit breaker types.

Main features at a glance, reliable opening and closing

_ Proven contact and arc-quenching system

_ Consistent quenching performance with rated and short-circuit currents even after many switching operations

_ Similar uncomplicated design for all voltages

High-performance, reliable operating mechanisms

_ Easy-to-actuate spring operating mechanisms

_ Hydraulic operating mechanisms with on-line monitoring

Economy

_ Perfect finish

_ Simplified, quick installation process

_ Long maintenance intervals

_ High number of operating cycles

_ Long service life

Individual service

_ Close proximity to the customer

_ Order specific documentation

_ Solutions tailored to specific problems

_ After-sales service available promptly worldwide

The right qualifications

_ Expertise in all power supply matters

_ 30 years of experience with SF6-insulated circuit breakers

_ A quality system certified to ISO 9001, covering development, manufacture, sales, installation and after-sales service

_ Test laboratories accredited to EN 45001 and PEHLA/STL