Clocks gaining time

IN January 2008, I wrote a letter pointing out there was a problem with the frequency control of the electricity generated by Eskom. At that time the problem was a frequency below 50Hz (cycles per second), causing electric clocks to lose time.

However the current (no pun intended) problem is of a frequency above 50Hz.

Many of your readers have probably noticed that, particularly recently, their electric clocks contained in bedside alarms, ovens, hifis, DVDs, etc have been gaining time. On one such clock that I monitored there was 18 minutes gained over a 21-day period.

Generally there is only one cause, other than a faulty clock, for such a phenomenon and that is that the electricity supply to the clock is not being supplied at the required frequency of 50Hz. If the supplied frequency deviates to as close as 50.05Hz, the effect would be approximately 1.5 minutes gain per day.

The reason that this time gain has not been evident on the in-built clocks of most personal computers is that the clock is run off a back-up battery supply. If this was not so then each time there was a power outage, or for that matter each time you switched off the power supply to the computer, the clock would stop and you would have to reset it.

The supply authority, in this case Eskom, could claim that the frequency range of its supply is within internationally accepted standards. This claim would not be good enough.

The ability to control the frequency at 50Hz is in its capability and has been successfully controlled for many decades, a feat for which Eskom has been justifiably proud in the past. At least it would be expected that if, for whatever reason, the frequency has been allowed to increase, then during the night the frequency would be allowed to decrease and in that way cancel out the gained time rather than let it accumulate.

Blackouts, of course, hide the problem in that after each blackout the consumers have to reset their clocks in any event. The current situation is, yet again, another symptom of reduced quality of service delivery.

This time gain, though more desirable than a time loss, is unnecessary and unacceptable.

Trevor Kay, Walmer, Port Elizabeth

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