Master clock is a clock mechanism which has high precision and can send time signals controlling secondary clocks. In the past, pendulum clock with higher precision than ordinary mechanical clocks was used as master clock. In order to ensure high timing precision of pendulum clock and maintain the pendulum's swing, electromagnetic theory was directly used to supply energy for the pendulum periodically. Such master clock’s time error can maintain within 1 second/day. With the development of science and technology, mechanical master clock is seldom used, and highly stable quartz master clock is largely applied and generally installed in central control rooms with good constant temperature and shockproof conditions. The master clock can receive standard UTC time signals from GPS satellite, automatically transform them to local time according to local time zone setting, and automatically complete calculation of leap year and leap second. 　　

Secondary clock is a clock mechanism controlled by the master clock, redisplaying master clock time and maintaining synchronization with master clock time. It meets users directly; therefore, its appearance, time accuracy and running reliability directly affect grade and value of master and secondary clock system. In appearance design, secondary clocks strive to coordinate and stand out field decoration styles, and achieve perfect integration of functions and aesthetics. Pointer secondary clock has many structures and forms. Common secondary clocks fall into two categories. One category is simulation secondary clock, also known as pointer secondary clock. Hour, minute and second pointers display time by rotating at respective constant speed according to requirements in a circular dial which is divided into 12/60 equal parts.