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The torque developed in the squirrel cage induction motor with auto-starter is ____________.
Question

The torque developed in the squirrel cage induction motor with auto-starter is ____________.

A.

K² × torque with direct switching

B.

K × torque with direct switching

C.

K²/torque with direct switching

D.

k/torque with direct switching

Correct option is A

Given:The torque developed in a squirrel cage induction motor with auto-starter.Starting torque (Tst), Full load torque (Tn), Starting current (Ist),Full load current (In), and full load slip (Sf).For an auto transformer starter, K represents the tapping of transformation ratio.Formula Used:For Direct Online Starter:TstTn=(IstIn)2SfFor Auto Transformer Starter:TstTn=K2(IstIn)2SfWhere:TstStarting torqueTnFull load torqueIstStarting currentInFull load currentSfFull load slipKTapping of transformation ratioSolution:The torque developed in a squirrel cage induction motor with an auto-starter is K2×torque with direct switching, as per the formula for the Auto Transformer Starter.\text{Given:} \\[4pt]\text{The torque developed in a squirrel cage induction motor with auto-starter.} \\[4pt]\text{Starting torque } (T_{st}), \text{ Full load torque } (T_n), \text{ Starting current } (I_{st}), \\[4pt]\text{Full load current } (I_n), \text{ and full load slip } (S_f). \\[6pt]\text{For an auto transformer starter, } K \text{ represents the tapping of transformation ratio.} \\[8pt]\textbf{Formula Used:} \\[4pt]\text{For Direct Online Starter:} \\[4pt]\dfrac{T_{st}}{T_n} = \left(\dfrac{I_{st}}{I_n}\right)^2 S_f \\[10pt]\text{For Auto Transformer Starter:} \\[4pt]\dfrac{T_{st}}{T_n} = K^2 \left(\dfrac{I_{st}}{I_n}\right)^2 S_f \\[10pt]\text{Where:} \\[4pt]T_{st} \rightarrow \text{Starting torque} \\[4pt]T_n \rightarrow \text{Full load torque} \\[4pt]I_{st} \rightarrow \text{Starting current} \\[4pt]I_n \rightarrow \text{Full load current} \\[4pt]S_f \rightarrow \text{Full load slip} \\[4pt]K \rightarrow \text{Tapping of transformation ratio} \\[10pt]\textbf{Solution:} \\[4pt]\text{The torque developed in a squirrel cage induction motor with an auto-starter is } \\[4pt]K^2 \times \text{torque with direct switching, as per the formula for the Auto Transformer Starter.}​​

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