DESIGN OF TURBO ALTERNATORS Length of Air-gap flow chart for overall design of alternators flow chart for main design of alternators

1. DESIGN OF TURBO
ALTERNATORS
DESIGN OF AC MACHINE
PREET PATEL(151310109032)

2. CONTENT
• Design of low speed and vertically operatedturbo alternator
• Length of air-gap
• Flow chart for overall design of alternator
• Flow chart for overall design of alternator
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3. DESIGN OF TURBO ALTERNATOR
𝑉 = 𝜋𝐷𝑛 𝑠
𝐷 =
𝑉
𝜋𝑛 𝑠
In low speed turbo-alternator the diameter is limited by the maximum
peripheral speed,
The output equation of ac machine can be modified by using the above relation.
The kVA rating or Output kVA, Q = C0 𝐷2 𝐿𝑛 𝑠
where,
C0 = 11 𝑎𝑐 𝐵𝑎𝑣 𝐾 𝑤 ∗ 10 − 3
Substitute , and the expression for C0 in the equation for Q
Q = 11 𝑎𝑐 𝐵𝑎𝑣 𝐾 𝑤
𝑉
𝜋𝑛 𝑠
2
𝐿 ∗ 10 − 3
Q = 1.11 𝑎𝑐 𝐵 𝑎𝑣 𝐾 𝑤 𝐿
𝑉
𝑛 𝑠
2
∗ 10 − 3
𝐷 =
𝑉
𝜋𝑛 𝑠
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4. The length of armature , L can be estimated from above equation.
The value of specific loading for conventionally cooled alternators
are,
𝐵 𝑎𝑣 = 0.54 𝑡𝑜 0.65 𝑊𝑏/𝑚2
𝑎𝑐 = 50000 𝑡𝑜 75000 𝑎𝑚𝑝.
𝑐𝑜𝑛𝑑
𝑚
The specific loading for conventionally cooled alternator are,
𝑃 𝑎𝑣 = 0.54 𝑡𝑜 0.65 𝑊𝑏/𝑚2
𝑎𝑐 = 180000 𝑡𝑜 200000 𝑎𝑚𝑝.
𝑐𝑜𝑛𝑑
𝑚
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5. LENGTH OF AIR-GAP
The length of air gap can be estimated from the ratio lg/τ = 0.02 to 0.025. It can
be also estimated from value of SCR.
mmf for airgap = 800000 𝐾 𝑔 𝐵 𝑔 𝑙 𝑔
mmf for airgap = 80% of no load field mmf 𝐴𝑇 𝑓0
Here, ATf0=SCR x 𝐴𝑇 𝑎; where 𝐴𝑇 𝑎 = 𝑎𝑐(𝜏/2);
Note:- 𝑆𝐶𝑅 = 0.5 𝑡𝑜 0.7 for turbo alternators and 𝐵 𝑔= 𝐵 𝑎𝑣/𝐾 𝑓
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6. On equating the two equation of mmf and mmf for airgap,
800000 𝐾 𝑔 𝐵 𝑔 𝑙 𝑔 = 0.8 𝐴𝑇 𝑓0
800000 𝐾 𝑔 𝐵 𝑔 𝑙 𝑔 = 0.8 x 𝑆𝐶𝑅 x 𝐴𝑇 𝑎
800000 𝐾 𝑔 𝐵 𝑔 𝑙 𝑔 = 0.8 x 𝑆𝐶𝑅 x 𝑎𝑐 x (𝜏/2)
𝑙 𝑔 =
0.8 x 𝑆𝐶𝑅 x 𝑎𝑐 (𝜏/2)
800000𝐾 𝑔 𝐵 𝑔
=
0.5 x 𝑆𝐶𝑅 x𝑎𝑐 x 𝜏
𝐾 𝑔 𝐵 𝑔x 106
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7. =
0.5 x𝑆𝐶𝑅 x𝑎𝑐 x 𝜏 x 10 − 6
𝐾 𝑔 𝐵 𝑎𝑣/𝐾 𝑓
The armature slot, winding, turns per phase and conductor design of
turbo-alternator are same as that of salient pole alternator.
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8. FLOW CHART
FOR
MAIN DIMENSION
OF
ALTERNATOR
start
P=(120*f)/n
𝐶 𝑂 =11* 𝐾 𝑤* 𝐵𝑎𝑣*ac*10−3
𝐷2
L= Q/(𝐶 𝑂 *(n/60))
D=𝑉𝑎𝑚/(П ∗ 𝑛)
L=(𝐷2
L)/𝐷2
τ= П*D/P
Select the suitable value of D
and L
end
𝐵𝑎𝑣,KVA , n, f ,m, pf, ac, ƞ, 𝐾 𝑤
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9. FLOW CHART
FOR
OVERALL
DESIGN
OF
ALTERNATOR
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10. THANK YOU