Patent ID: 8298391

Claim:
A sensor that performs conductivity measurement, amperometric chlorine or bromine measurement and measurement of oxidation reduction potential of water in a water system, the sensor comprising: no more than three electrodes, including a first electrode and a second electrode and a reference electrode; an auxiliary voltage circuit that generates an auxiliary voltage in accordance with a selected one of a conductivity measurement, an amperometric chlorine or bromine measurement and an oxidation reduction potential measurement to be performed; a voltage difference circuit; a current to voltage converter; and a control circuit that selectively configures the first and second electrode in one of a first configuration and a second configuration to measure amperometric chlorine or bromine in the first configuration and to measure oxidation reduction potential in the second configuration, wherein: in the first configuration, one of the first and second electrodes is connected to the auxiliary voltage circuit and the other of the first and second electrodes is connected to the current to voltage converter to enable measurement of chlorine or bromine concentration and to enable measurement of conductivity; and in the second configuration, one of the of the first and second electrodes is connected to the auxiliary voltage circuit and the other of the first and second electrodes is unconnected, the auxiliary voltage and a voltage from the reference electrode being provided to the voltage difference circuit to enable measurement of oxidation reduction potential.