Monthly Archives for June 2019

Resistance-Start Induction-Run Motor

The rotating magnetic field of the resistance-start induction-run motor is produced by the out-of-phase currents in the run and start windings. Since the run winding appears more inductive and less resistive than the start winding, the current flow in the … Continue reading

05. June 2019 by admin
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Return grille sound requirement

Return air grilles should be selected for static pressures. These pressures will provide the required NC rating and conform to the return system performance characteristics. Fan sound power is transmitted through the return air system as well as the supply … Continue reading

04. June 2019 by admin
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HVAC Controlling Casing Noise

Terminal boxes can sometimes be located over noisy areas (corridors, toilet areas or machine equipment rooms), rather than over quiet areas. In quiet areas casing noise can penetrate the suspended ceiling and become objectionable. Enclosures built around the terminal box … Continue reading

03. June 2019 by admin
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Types of Registers and Grilles

The spread of an unrestricted air stream is determined by the grille bar deflection. Grilles with vertical face bars at 0° deflection will have a maximum throw value. As the deflection setting of vertical bars is increased, the air stream … Continue reading

01. June 2019 by admin
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HVAC Air Noise

High velocities in the duct or diffuser typically generate air noise. The flow turbulence in the duct and the excessive pressure reductions in the duct and diffuser system also generate noise. Such noise is most apparent directly under the diffuser. … Continue reading

01. June 2019 by admin
Categories: Control Devices | Tags: | Leave a comment

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