Sensorless Control Technology
Equipped with the Sensorless design feature, Armstrong IVS pumps do not require an external sensor to monitor and control the HVAC load.
In a chilled water system, a building's temperature controls are connected to control valves that manage the flow rate to the cooling coils (load). As the control valves open for more cooling, the differential pressure across the valve decreases. The IVS controller reacts to this change by increasing the pump speed to maintain the pressure setpoint. If the control valves close to reduce the cooling output, the differential pressure across the valve increases, and the IVS controller reduces the pump speed to maintain the pressure setpoint.
Equipped with the IVS Sensorless feature, a pump's performance characteristic curve is programmed into the memory of the pump controls. A control curve is also programmed into the pump controls, with a minimum required system head at zero flow pre-set. During operation, the sensorless controller monitors the power draw and speed of the pump, establishes the flow requirement of the system and controls the pump so that the operating point sits on the control curve. As two port control valves open and shut, the controller automatically adjusts the pump speed so that it matches the system demand while keeping the pump operating at minimum speed on the control curve. This guarantees the lowest life cycle cost.
Parallel Sensorless pump controller
Multiple single Sensorless control pumps cannot operate ef�fectively in larger systems. If installed as such, each Design Envelope pumping unit will operate by producing its share of the present load flow requirements, as usual; however at lower loads all the pumps will continue to reduce speed together instead of units staging off. Armstrong solved this issue by integrating a Parallel Sensorless pump controller on one of the multiple pumps. The controller is wired to all single pump controls and reads the Sensorless information from each. The system control curve is mapped into the controller and the controller intelligence then meets the system flow while staging the pumps on and o to maintain optimum pump energy usage. This is accomplished by operating the pumping units at the best pumping effciency level for the required flow. This controller is available for all Sensorless pumping units to a total quantity of 4. This can be up to 4 operating pumps or up to 3 duty/1 standby.