HVAC Control in the New Millennium.pdf - HVAC.Amickracing

HVAC Control in the New MillenniumFigure 2-4. Electrical meter connections. The timing pulse marks theend of each demand period. The kWh pulse occurs at each rotation ofthe meter rotor.Meters can be modified by the utility company for about $500 to$1000. External clock mechanisms or timing signals can also be used.The energy (kWh) consumption pulse value is converted to a unit ofdemand (kW) by dividing it by the demand period length in hours.kWh per PulseDemand Period in Hours =kW(Demand)The simplest power control device is a timer or time clock. Anelectromechanical timer or clock has a small electrical motor and anarrangement of cams and switches. These switches allow several loadsto be operated in a cyclical mode by turning them on or off at preset©2001 by The Fairmont Press, Inc. All rights reserved.