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Master clock HUS124 |
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| Year of manufacture: | 1975 |
| Manufacturer: | Elektročas (Electric Time Company), Prague |
| Description: |
The synchronised clock system is used in factories, schools, hospitals, railway stations, office buildings etc.. The principle is that all the clocks in the rooms are controlled from a central master clock, so it is ensured that all the clocks show correct time and if they need to be set e. g. because of the daylight saving time, they can be set centrally without needing to set each clock separately. The clocks are connected to the master clock with a two-wire line, into which a voltage impulse is sent each minute by the master clock. The polarity of the impulses alternates. At first, precise mechanical pendulum clock was used as the master clock, later it was superseded by electronic quartz-controlled clock.
This master clock was placed in the Motol hospital in Prague. For such a big institution, it was necessary to divide the system into multiple lines, so a fault on one of the lines would not influence the operation of the clocks in the whole hospital. Each line is equipped with its own relay repeater, short circuit protection, checking clock and ampere meter. It is also possible to measure the insulation of the lines and detect imminent failures in time. The master clock uses two pendulum clocks. Both machines run synchronously. If the main machine fails, the system automatically switches the control to the backup machine. The master clock system is still used in the same form up to today, only the master clock is digital, with a DCF77 or GPS radio time receiver. |
