This relay set generates an S and a Z pulse approximately every 90 seconds. It is used to control the power equipment. Normally when the main rectifier is in use, it is off, although a time clock does switch it on for two half hour periods a day to keep the batteries charged. Whenever the exchange is taken into use the rectifier switches on and then remains on for several minutes after the call clears down.

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Page provided by John Bathgate This page was last updated on 2nd July 2012