The University asked us to supply a replacement Master Clock Controller as their old one had broken down and was an obsolete type.

There are several hundred analogue system slave clocks on Campus in two separate circuits. Both systems are IBM 3-wire protocol but one is at 230VAC and the other is 24V DC +/- (SR2).

The 24V system is a standard SR2 hourly corrective accumulator system while the 230v system is synchronised by a "short" and a "long" pulse corrective signal at different times of the day.

Both clock types are in common use worldwide and in current production by several overseas manufacturers. Master Controllers to both specifications are readily available and it was decided to replace with a standard Controller of a modern specification.

However, on investigation of the old Master Clock programming it was discovered that the 230V "short pulse" activation had been disabled for some reason. When tests of the clock system were conducted by a computer software test program, it was found that not all clocks responded correctly to the short pulse which pointed to a major service issue on an unknown number of slave clocks. It was decided that the new Controller should avoid the short pulse generation to avoid major disruption of the majority clock system.

This meant we could not supply a standard Controller as these produce all required pulses on demand. However we were able to supply a Tempus P which is highly configurable and able to be programmed to drive both the system clocks to the customer specifications.

In these two pictures alongside, Barry Rowley (Electrical Leading Hand, Property Services at UOO) and Garth from Jira, have removed the old Master Controller. This was made about 20 years ago by a UK company called Plessey who are no longer active in NZ.

As can be seen in the second picture, the new Tempus Controller has been fitted and is being wired to the correct specification.

The Clock 24V system depends on relay re-transmitters located in each building on Campus with additional re-transmitters on each floor.

The relay unit here is made by a company called Simplex who were at one time active in NZ.

This picture shows the replacement Tempus controller.

It is fully automated for in the event of power failures and for unattended NZ DST

A special indexing feature permits timekeeping accuracy of better than 2 seconds per year without need for external synchronisation (eg GPS or NTP etc).