Introduction to Clock Systems

 Clock Systems Overview   Clock Selection Guide

Introduction to Clock Systems


120V and 24V Wired Clock Systems

Synchronous Motor Driven Clock Systems

Dominating the market from the 1930’s into the 21st Century, this clock system is the undisputed king of master clock systems. It has proven itself to be accurate, reliable and powerful enough to drive the large clock hands necessary for long distance viewing like gymnasiums and large assembly areas. Many National Time and Signal systems have been in constant operation for over 30 years. Another benefit of their electromechanical design is their very high tolerance of electrical surges making them a great choice for regions that experience frequent electrical storms.

Rotary Drive Universal Clock Systems

National Time and Signal invented this clock system in 1990 to address the needs of the market for a replacement clock for a wide variety of popularly installed systems. The design criteria for this clock system focused on three principles: Universal Application, Life Expectancy equal to the practical life of the facility and Energy Efficiency. Like the synchronous motor clock system, the rotary drive clock system features a robust design to drive very large clock hands. With an electrical power cost of about $.10/year, to our knowledge all systems installed since 1990 remain in operation today.

Economy Clock Systems

A frequent choice of those who are most concerned with initial cost, economy clock systems are based upon a much lighter duty mechanism popularized by the battery clock system manufacturers. Initially employed by the wireless battery clock industry, almost all manufacturers now use them for their wired applications as well. Because they are able to operate on battery power, this clock system is very energy efficient when used in wired clock system applications. A necessary characteristic of these clocks is the smaller, less visible clock hands they can support and, since they are a comparatively new introduction to the market, time will tell what their life cycle will be.

Digital Clock Systems

Digital clock systems began to appear more frequently in educational, medical and industrial applications around 25 years ago. Although the analog clock continues to be the first choice for most elementary and middle school applications, more high schools are turning to digital clock displays. Early introductions of digital clocks were met with disconcerting numbers of failures in both LCD and LED displays. Today, the best engineered and manufactured digital clock systems can be expected to last 20 years or more. Due to the higher level of current required to operate lighted displays, almost all of these are wired clock systems. They may be locally powered with 120VAC or powered from a central 24VAC supply. In the latter configuration, these systems are most cost effectively corrected over the 24VAC power wiring.
Where analog clocks have the advantage of offering a graphic display of time, digital clocks can be utilized in timer functions as well. Schools may use them for class change countdown timers or test timers and hospitals may find them more accurate for recording time based functions so prevalent in medical applications.

Power Over Ethernet Clock Systems (P.O.E.)

P.O.E clock systems have been developed to offer a network time based option in synchronized clock system installations. The value of this option may have been minimized with the advent of Wi-Fi clock systems. The main detractors of this technology relate to the cost of the supporting infrastructure and installation. Most other wired clock systems will operate off two or three low voltage conductors wired in parallel rather than an individual CAT5 drop to every single clock. This represents a significant installation savings in most applications. For larger installations, these systems will typically be the highest initial cost.

Typical Digital Clock or Analog Clock Applications

Educational and medical facilities account for a large percentage of clock system installations. Both system styles are used in these facilities. Sometimes, their selection is a matter of personal preference and sometimes the choice is by design. For instance, K-12 schools may choose analog clocks for their elementary and middle schools as an educational tool. Hospitals may choose analog clocks in some locations for the sweep second hand reference and digital clocks where time recording or timing functions are important. Modern clock systems are capable of intermixing digital and analog clocks where it is desirable to have both styles within a facility.
Many perceive the main benefit of analog clocks to be the graphic display of time. The picture of the clock resides in our brains making it very easy to order our day. With a simple glance, we can see segments of time that are easily understood references. Digital clocks, being numerical rather than pictorial, may not be as readily assimilated for most people.
Perhaps of interesting note, it is said that Albert Einstein refused to have digital clocks in his home and study areas as the representation of time as “static” was wholly inconsistent with his thought process that led to the extraordinary findings of time and motion in his “Special Theory of Relativity” published in 1905.


Battery Wireless Clock Systems

Radio Frequency Analog Clock Systems

In the early 2000’s, radio frequency correctable clock systems became popularized. Today, they represent the majority of new clock systems specified in educational occupancies. The main benefits claimed by the proponents of these systems are:

  1. Price savings due to the elimination of wiring costs.
  2. Newer technology.
  3. Flexibility in design and clock location.

However, no one clock system is the best choice for all applications and facility owners as well as their construction design team might benefit from a close inspection of alternative options.

Wi-Fi Analog Clock Systems

The latest technology in clock system evolution is Wi-Fi correctable clocks. This technology promises to be the future of synchronized time display in buildings the world over. With Wi-Fi, all of the advantages of the various clock system options are possible without their respective drawbacks. The advent of widely distributed Wi-Fi communication networks has made Internet time available without the added costs of POE installations or RF transmitters. Wi-Fi technology can be applied to wired systems as well as battery operated systems. Since the overwhelming majority of facility operators already own a Wi-Fi network, the installation of a single clock is as cost effective as 100. There is no need to purchase any additional controllers or radio frequency transmitters and building owners can free themselves of “captive client” pricing practices of some proprietary clock vendors. The benefit claims of Wi-Fi proponents are:

  1. Price savings due to elimination of wiring costs.
  2. Price savings due to elimination of proprietary controllers and transmitters.
  3. Future technology.
  4. More reliable correction signal distribution over common RF transmitters means more reliable performance.
  5. Flexibility in design and clock location.