The ZE I is a spring-driven 80-day mechanical sterilizing clock used in the EMC, EMD, EMF, SMA, TMA, and TMB mines.

Operation. Closure of UES contact allows current to flow through solder plug T of the ZE I, figure 268. When T melts, it releases clock-starting lever L. 40 to 50 minutes after the ZE I starts, switches C, D, E, and F are closed. C and D put the clock safety feature into the circuit; E and F switch the detonator into the circuit and make the mine ready for normal firing. At the end of the preset period, contacts C, E and F open and A and B close. A and B put the battery across the flooder detonator, and the resulting explosion scuttles the mines. (Figure 269).

Figure 268 – ZE I

Figure 269 – Operation of ZE I