Example 01 : 22KW 6 poles 415 V 50 Hz

Youtube link:

22 KW 30HP 72 Slot 6 Pole 975 RPM full Motor Winding with Connection Diagram DoubleDelta Connection

1) Nameplate data:

U = 415 V

I = 42.6 A

f = 50 Hz

P.F. = 0.79

eff = 90.9%

conn: Delta

TClass/Rise: F

amb: 50°C

weight: 230 Kg

n = 975 rpm

IP 55 

Duty S1

2) Data from video: 

Di = 200 mm;  Dout = 300 mm;  L = 250 mm; 

72 slots; 

18 sets; 2 coils/set (pitch: 1-10 & 1-12); 26 turns/coil (3 wires in parallel: SWG #19 #20 #21)

Copper Weight: 800 grams/set 

Double Delta connection

3) Approximate calculations

Assume: kws = 0.955

KVA  Rating

Q=22/(0.79*0.909)=30.63597 KVA

Sync speed

n=975 rpm ---> n_s=1000 rpm ---> Ns=1000/60=16.666 rps

# poles

p = 2*50/16.666 = 6 poles

Polar pitch

Tau = (Pi*Di)/p = 0.104719 m

Form factor 

Lambda = L / Tau = 0.25 / 0.104719 = 2.387 ~ 2.4

Phase current

Iph=42.6/sqrt(3)=24.59512 A

2 Delta connection ----> Paths = 2

Conductor current

Iz = Iph/2 = 12.2975 A

Conductor area

as = #19 + #20 + #21 = 0.8107 + 0.6567 + 0.5189 = 1.9863 mm^2

Current density

dens = Iz/as = 6.19116 A/mm^2

Output Constant

Co = Q/(Di^2*L*Ns) = 183.81589 KVA.seg/m^3

Specific Electric Loading

ac = (26*72*12.2975)/(Pi*0.2) = 36638.932 A.c/m

Specific Magnetic Loading

Bav = Co/(1.11*Pi^2*ac*kws*10^-3) = 0.47952 T

Flux per pole

Flux = Bav*(Tau*L) = 0.0125537 Wb

Turns per phase

Tph = 415/(4.44*Flux*50*kws) = 155.926 turns ~ 156 turns/phase

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Winding design (alternate poles; double parallel)

72 slots

18 sets

2 coils / set  ---> 18 * 4 = 72 active sides  

72  active sides in 72 slots  ---> single layer

q = 72 slots / (6 poles * 3 phases) = 4 slots / (pole*phase)

pitch: 1-10 & 1-12

18/3=6 sets / phase

Double delta connection: 2 paths in parallel / phase

6/2 = 3 sets/path  (3 sets connected in series) 

Then: 3 sets = 6 coils in series / path

156 turns / 6 coils = 26 turns / coil

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Copper weight (approximate)

Assume: Cu_density = 8.86 g/cm^3

Lenght of mean turn (1-10 + 1-12)

Lmt = 2*L + Pi*(10/12)*Tau + 2*L + Pi*Tau = 4*L+Pi*Tau*(11/6) = 1.603138 m

Cu_weight (1 set) = 26*160.3138 cm *(1.9863mm^2*10^-2)cm^2*8.86 g/cm^3 = 733.538 g 

Real Cu weight  = 800 g (diff ~ +9 %)

Cu_Weight (total) = 26*18*160.3138 cm *(1.9863mm^2*10^-2) cm^2*8.86 g/cm^3 = 13203.69 g

Real Cu weight (total)= 800 g * 18 = 14400 g

% Cu / Motor weight

(14.4 Kg /230 Kg)*100 = 6.26 %