Leeson Micro Series Compact Inverters Bedienungsanleitung PDF herunterladen (Seite 20)

 Ifthefrequencyappliedtothemotorisincreasedwhilethevoltageremainsconstant,torquecapabilitywill

decreaseasspeedincreases.Thiswillcausethehorsepowercapabilityofthemotortoremainapproximately

constant. Motors run in this mode when operated above base speed, where drive output voltage is limited

bytheinputlinevoltage.Thisoperatingrangeisknownasthe“constanthorsepower”range.Thetypical

maximumrangeforconstanthorsepowerisabout2.3to1(60to140Hz).Thediagrambelowdepictsthe

operatingcharacteristicsofatypicalACinductionmotorwitha60Hzbasespeed.

 Consultmotormanufacturerbeforeoperatingmotorand/ordrivenequipmentabovebasespeed.

6.1.1 VARIABLE TORQUE VS CONSTANT TORQUE

 Variable frequency drives, and the loads they are applied to, can generally be divided into two groups:

constanttorqueandvariable torque. Constant torqueloadsinclude: vibrating conveyors, punch presses,

rock crushers, machine tools, and just about every other application that is not considered variable

torque.Variabletorqueloadsincludecentrifugalpumpsandfans,whichmakeupthemajorityofHVAC

applications.

 Variabletorqueloadsaregovernedbytheaffinitylaws,whichdefinetherelationshipsbetweenspeed,flow,

torque,andhorsepower.Thediagrambelowillustratestheserelationships:

WARNING

CONSTANT TORQUE

CONSTANT HP

TORQUE (PERCENT)

TORQUE

HORSEPOWER

TORQUE

HORSEPOWER

150

130

110

50 60

70 80 90 100 110

120

100%

75%

50%

25%

0%

0% 25% 50% 75% 100%

% SPEED

% FLOW

% TORQUE

% HORSEPOWER

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Leeson Micro Series Compact Inverters Bedienungsanleitung Seite 20