Averaging relays have two inputs (some have four), main air and branch ports. The branch port signal is the average of the input signals. CAUTION: One input signal may indicate an extremely hot room and the other input signal may indicate an extremely cold room, but the average indicates that all is well. Pilot positioners (positive positioners) sense the stroke of the valve or damper actuator from 0% to 100%. The controller signal does not go directly to the valve or damper actuator. It goes only to the pilot positioned indicating the required percentage of stroke. The pilot positioned uses from full main air pressure to zero PSIG positioning the device as requested. Addition relays are also available from Kreuter and have two input signals, main air and branch signal ports. The branch signal is the sum of the two input signals, but cannot exceed the main air pressure. The branch signal may also be biased. They are useful in conservation loops if you wish to simulate a transmission signal greater than the actual condition. Subtraction relays are available from Kreuter and have two inputs, main air and branch ports. The branch signal is the product of subtracting port 2’s signal from port 3’s signal (KREUTER). The branch signal can also be biased. They are useful in conservation loops such as enthalpy comparison between outdoor air enthalpy and return air enthalpy. CONTROL RELAYS SUBTRACTION ADDITION RELAY RELAY M B M B INPUT INPUT INPUT INPUT AVERAGING POSITIVE POSITIONER RELAY (PILOT POSITIONER) DAMPER VALVE ACTUATOR B M M B P P INPUT INPUT B M 2.14
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