Central desk air conditioning control system

Claim 1

An air conditioning system including a plurality of air conditioning units and a central control system, said air conditioning system comprising: at least one major energy-consuming load included in each of said air conditioning units; relatively local control circuitry respectively connected to each of said air conditioning units for directing the respective major energy-consuming load to cycle on and off as required to maintain a desired temperature in a space conditioned by the respective units; circuitry included within each of said air conditioning units defining a reference potential, and a terminal at the reference terminal; a controlled power switching circuit for the respective major energy-consuming load included within each of said air conditioning units, each of said controlled power switching circuits having both a normal mode in which said major energy-consuming load operates in response to said local control circuitry to maintain the desired temperature and a low-energy mode in which operation of said major energy-consuming load is disabled, and each of said controlled power switching circuits having a control input effective when connected to the reference potential to select one of said modes and effective when not connected to the reference potential to select the other of said modes; a relatively remote control switch for each of said air conditioning units, each of said relatively remote control switches having two terminals connected via conductors respectively to said reference terminal and to said control input in the corresponding air conditioning unit such that said one of said modes is selected when said remote control switch is closed without affecting said relatively local control circuitry; and a protective network included in each of said air conditioning units interposed between said conductors and said reference terminal and said control input, said protective network including elements arranged to prevent damage to said local control circuitry, said reference circuitry, or to said power switching circuit in the event voltage of either polarity is inadvertently applied to said conductors.