Page 670 - Industrial Power Engineering and Applications Handbook

Circuit interrupters 19/635

(Courtesy Siemens) (Courtesy: GE Power Controls)
Figure 19.9(a) Views of air circuit breakers

(Courtesy: Alsthom) Figure 19.10 Typical contact arrangement of an LT air circuit
breaker
Figure 19.9(b) ACB in housing
ACBs were the first to be produced commercially. are used extensively. In fact, they are the only breakers
They are simple to operate and cause no fire hazards. to meet the needs of an LT distribution system.
But at atmospheric pressure, they possess a low dielectric
strength and are therefore normally manufactured only 19.5.4 Air Blast Circuit Breakers (ABCBs)
in low voltages. Air has less contamination and therefore
these breakers require negligible maintenance, compared Refer to the general arrangement of this breaker in Figure
to oil. They require no contact cleaning. Since there is a 19.1 3( a).
limit to producing these breakers for HT systems, their These are similar to ACBs, except that the process of
normal application is for LT systems alone, where they interruption is accelerated by impinging a high pressure