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# ISA Northern California Section, South Bay .

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How Do You Size an Adjustable Frequency Drive?. . Measuring AFDs. Key elementsThe loadThe engine The force supplyThe environmentThe obligation cycleThe mounting spaceThe spending plan. Measuring AFDs - The Load (1). What amount of beginning torque?Centrifugal pump or fan?110% beginning torque typically sufficient (VT)Conveyor?150% beginning torque (CT)Is 200% breakaway torque required? The AFD business helpfully has (2) rating
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﻿ISA Northern California Section, South Bay September 9, 2003 Craig Chidester 909 288 7990

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How Do You Size an Adjustable Frequency Drive?

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Sizing AFDs Key components The heap The engine The power supply The environment The obligation cycle The mounting space The financial plan

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Sizing AFDs - The Load (1) How much beginning torque? Radiating pump or fan? 110% beginning torque generally sufficient (VT) Conveyor? 150% beginning torque (CT) Is 200% breakaway torque required? The AFD business helpfully has (2) evaluations: 110% or 150% for 60 seconds

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Sizing AFDs - The Load (2) High inactivity stack (rotator?) An axis needs 40HP @ 1160RPM to run Centrifuge weighs 6000 lbs discharge, 3 feet width; Wk 2 = 11,760 lb-ft 2 Std engine starter 650% inrush until 65% speed, set time at 30 sec\'s 120% normal torque until 65% speed Tq = (Wk 2 x ΔN)/(308 x t) Tq = 11,760 x .65 x 1160/308 x 30 = 960 ft-lbs/120%/4.5 ft-lbs/HP = 178HP Voltage drop, stiction, stacked - 200HP min

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Sizing AFDs - The Load (3) But with an AFD … . Objective is to get engine to 70% speed in 60 seconds while restricting inrush to 150% Tq = (Wk 2 x ΔN)/(308 x t) Tq = 11760 x .70 x 1160/308 x 60 = 517 Ft-lbs 517/150% = 345 Ft-lbs nonstop 345 ft-lbs/4.5 ft-lbs/hp = 76 HP - utilize 100HP Δt = 11760 x .30 x 1160/308 x 345 = 39 sec\'s Total time = 60 + 39 sec\'s = 99 sec\'s (76 sec\'s utilizing 100HP)

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Sizing AFDs - The Load (4) Compare engine warming … . (I 2 r)t watt-seconds of vitality -  I 2 t ("Figure of Merit") FV begin "(650%) 2 x 30 sec" = "1267" AFD begin "(150%) 2 x 60 sec" = "135" Both "FofM\'s" disregard the last part of every beginning cycle which are similar

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Sizing AFDs - The engine Sizing AFD depends on engine HP is dangerous to your wallet!! AFD\'s are present evaluated - HP\'s are appointed Typical case, 150HP AFD is appraised 189A 150HP, 450RPM engine evaluated 224A … dependably check engine NP current rating And, numerous apparatus OEM\'s utilization part of the engine\'s administration element to decrease cost

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Sizing AFDs - The power supply (1) Voltages: 208V, 230V, 380V, 460V, 575V, 2300V, and so on Single and three stage 50 and 60 Hertz Available short out current 65,000A ? Higher ? Symphonious Distortion issue?

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Sizing AFDs - The influence supply (2) Harmonic twisting IEEE-519 (most recent version) is the Guideline Typically prescribes 5% THD (V and I) Point of Common Coupling (PCC) is key With 3% gag, < 35% AFD stack at PCC < 5% THD(V) at 460V side Locate PCC for THD(I) on 4160V (MV) side Otherwise, spend an entire group of cash

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Sizing AFDs - The environment AFD\'s are appraised for encompassing and height 110% (VT) generally 40C (104F) 150% (CT) normally 50C (122F) 20% derate to get from 40C to 50C 3300 feet rise greatest standard 3% derate per 1000 feet over 3300 100HP VT, 50C, 6000 ft = 137HP (150HP) Outdoors? Sun stack includes 60 watts/Sq ft (in view of most extreme face measurement)

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Sizing AFDs - The Duty Cycle AFD\'s are appraised 100% current ceaselessly And … 110% (VT) or 150% (CT) for 60 seconds in a 10 minute interim Cyclical burdens that require monotonous accel torque may should be larger than usual "FofM" for CT = I 2 t = (150%) 2 x 60="135" If same load is accel\'d in 25 sec\'s at regular intervals at 135%, then FofM is "227" "227"/"135" - 1.69 X base HP

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Sizing AFDs - The Mounting Space Once a rating and changes/frill have been set up, check for space necessities! Not all sellers are made equivalent Modern AFD\'s consume less room Configurations are "scene or representation" Tradeoffs on divider space versus impression

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Sizing AFDs - The Cost Bare Bones Loaded 1HP - \$ 325 \$ 2000 (1) 10HP - \$ 1200 \$ 3000 (1) 100HP - \$ 7500 \$30000 (2) 500HP - \$35000 \$90000 (2) Bare Bones: 460V, Nema 1 encl, VT Loaded: (1) Ditto in addition to sidestep, Loaded: (2) Ditto in addition to sidestep, MMR w/CTs and PTs, yield channel and 18-beat

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