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A programmable maintenance timer system suitable for use with industrial equipment such as a centrifugal water chilling system and a telemetry system including a microprocessor-based computer with a programming device for presetting selectively a maintenance time interval representing a number of ho

A programmable maintenance timer system suitable for use with industrial equipment such as a centrifugal water chilling system and a telemetry system including a microprocessor-based computer with a programming device for presetting selectively a maintenance time interval representing a number of hours before a maintenance service is to be performed, for counting down the time interval to zero, and for generating an output signal after the time interval has reached zero to the telemetry system so as to alert service personnel that the industrial equipment is due for a scheduled maintenance. The timer system also includes a non-volatile memory device to record permanently the total elapsed operating hours in the preset maintenance time interval so as to avoid loss of such information upon a power failure and/or back-up battery failure.

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1. A programmable maintenance timer system suitable for use with industrial equipment such as a centrifugal water chilling system and a telemetry system, said timer system comprising: interface circuit means for receiving an AC electrical signal and for generating a pulse signal in response to sa

1. A programmable maintenance timer system suitable for use with industrial equipment such as a centrifugal water chilling system and a telemetry system, said timer system comprising: interface circuit means for receiving an AC electrical signal and for generating a pulse signal in response to said electrical signal; a microprocessor-based computing means for calculating a signal representative of total elapsed operating hours of an industrial equipment in response to said pulse signal; said microprocessor-based computing means including programming means for presetting selectively a maintenance time interval representing a number of operating hours before a maintenance service is to be performed, for counting down said time interval to zero, and for generating an output signal after said time interval has reached zero to a telemetry system so as to alert service personnel that the industrial equipment is due for a scheduled maintenance; display means responsive to said signal representative of the total elapsed operating hours for indicating visually the total elapsed operating hours; and function programming switching means for controlling mode of operating of said microprocessor-based computing means; said switching means including a mode switch for activating said display means to indicate either the total elapsed operating hours, the hours remaining on the maintenance time interval before reaching zero, or the preset maintenance time interval; a reset/up switch for returning the maintenance interval to the beginning preset maintenance interval value so that it counts down again to zero and for adjusting selectively by increasing the desired maintenance interval; and a down switch for adjusting selectively by decreasing the desired maintenance interval. 2. A programmable maintenance timer system as claimed in claim 1, wherein said microprocessor-based computing means further generates a programming voltage signal, and wherein a non-volatile memory device responsive to said programming voltage signal is provided for recording permanently the total elapsed operating hours and the preset maintenance time interval so as to avoid loss of such information upon a power failure and/or a battery back-up failure, every ten hours of count pulse accumulation, and every time the reset/up switch is activated. 3. A programmable maintenance timer system as claimed in claim 1, wherein said microprocessor-based computing means comprises an 8-bit microprocessor, and wherein a non-volatile memory device comprises an electrically erasable programmable read-only-memory, said display means comprises a 5-digit, 7-segment light-emitting diode display unit, and said interface circuit means comprises a divider network and a photo-coupler. 4. A programmable maintenance timer system as claimed in claim 1, further comprising inverter/buffering means connected to said microprocessor-based computing means for generating said output signal, and wherein said maintenance time interval is adjustable between 1 to 9,999 hours.