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WEEK 17: INDUCTION MOTOR (SQUIRREL CAGE) ARMATURE DESIGN NOTES


Legend: Formula: : Formula | Limits: : Limits, Range | Notes: : Notes


Updated: Saturday, October 06, 2000

<-- Back Items 12 - 17

Item 18. Slot pitch, l
Formula: Use: Use: Use: l = t / (S/p)
Notes: Round-off to three decimal places.

Item 19. Number of Conductor per slots, Cs
Formula: Use: Cstrial = qtrial × l / Ic.
Notes: Csfinal is a whole number of Cstrial.
Solve for the equivalent specific loading, qfinal, using the Csfinal.

Item 20. Stator Conductor in Series per phase, Z
Formula: Use: Z = p × ns × Cs.
Notes: Should be a whole number based on the most appropriate combination of Slots per Pole per Phase: ns and Number of Conductors per slot: Cs.

Item 21. Air Gap Flux per pole (open circuit), FNL
Formula: Use: FNL = Vt × 108 /  × 2.22 × d × f × Z .
Notes: Rounded to nearest 10,000 maxwells.

Finalize B"gave and B"gmax in Item 06

Item 22. Maximum Apparent Tooth Flux Density , B"t
Formula: Use: B"ttrial = 85,000 lines/sq.in.
Formula: Use: B"tfinal = B"ttrial × [ t / tend ]
Limits: For 60-hz machines, between 75,000 to 105,000 lines per sq. in..
Notes: Rounded-off to nearest 1,000.
Formula: Use: B"t1/3 = B"tfinal × [ tend / t1/3 ]

Item 23. Tooth Dimensions
Formula: Use: ttrial = l / 2 + 0.027.
Notes: This item SHOULD serve only as a guide.

Item 23a. Permissible Tooth Width, t
Formula: Use: t = B"gmax × l × la / ( B"ttrial × ln ).
Notes: Other values of tooth widths should not exceed this value.

Item 23b. Narrow End Tooth Width, tend
Formula: Use: tend = t - 0.025
Notes: Rounded to the nearest two decimals.

Item 23c. Tooth Width at Top, Near Air Gap, ttop
Formula: Use: ttop = [( pD - s ) / SA ] - s
Notes: Where s = slot width
SA = Number of Armature
Rounded to the nearest three decimals.

Item 23d. Tooth Width at Root, troot
Formula: Use: troot = [ p (Do - 2Rdfinal ) / SA ] - s
Notes: Where s = slot width
SA = Number of Armature
Rounded to the nearest three decimals.

Item 23e. Average Tooth Width, tave, tmid
Formula: Use: tave = ½ (ttop + troot )
Notes: Rounded to the nearest three decimals.

Item 23f. Tooth Width at 1/3 of Slot Depth from Root, t1/3
Formula: Use: t1/3 = tend + 1/3 (troot - tend )
Notes: Rounded to the nearest three decimals.

 Items 24 - 32


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