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Blocking. A block circuit, figure 253, is used to block firing if
the subsonic influence causes the "T" component to react prematurely.
(Contact r2 closes when the "T" compo-nent fires). If
the "T" component reacts prematurely, ZR II cam 6, will be on its blocking
contact when r2 closes. The low-resistance coil of R4
(R5H) is energized and r5
switches over, energizing the high-resistance coil (R5H),
whih acts to produce self-holding of R5 as long as r2
remains closed and the resistance of R5H prevents
detonator firing. |
