Consider the following statements: Assertion: Single-phase induction motor is not self-starting. Reason: Net rotating magnetic field produced by single-phase winding at standstill is zero. Of these statements:
Answer & step-by-step solution
At standstill a single-phase stator field can be resolved into equal forward and backward rotating fields. Their starting torques are equal and opposite, giving zero net starting torque; hence the motor is not self-starting. Both assertion and reason are true and the reason correctly explains the assertion: option A.
Concept and Reasoning
At standstill a single-phase stator field can be resolved into equal forward and backward rotating fields. Their starting torques are equal and opposite, giving zero net starting torque; hence the motor is not self-starting. Both assertion and reason are true and the reason correctly explains the assertion: option A.
Calculation / Key Relation
At standstill: Tf=Tb in opposite directions → Tnet=0
Exam Takeaway
Single-phase induction motor needs an auxiliary starting means because forward/backward torques cancel at rest.
Common Mistake
After the rotor starts, the two slips differ and the torques no longer cancel.
Quick Trick
Single-phase induction motor needs an auxiliary starting means because forward/backward torques cancel at rest.
निम्नलिखित कथनों पर विचार कीजिए: अभिकथन: सिंगल-फेज़ इंडक्शन मोटर स्व-प्रारंभी (self-starting) नहीं है। कारण: स्थिर अवस्था में सिंगल-फेज़ वाइंडिंग द्वारा उत्पन्न शुद्ध घूर्णी चुंबकीय क्षेत्र शून्य है। इन कथनों में से:
उत्तर और चरणबद्ध हल
स्थिर अवस्था में सिंगल-फेज़ स्टेटर क्षेत्र को बराबर आगे और पीछे घूमने वाले क्षेत्रों में विभाजित किया जा सकता है। उनके प्रारंभिक टॉर्क बराबर और विपरीत होने से शुद्ध प्रारंभिक टॉर्क शून्य है; अतः मोटर स्व-प्रारंभी नहीं है। दोनों सही हैं और कारण सही व्याख्या है: विकल्प A।
विस्तृत हल (मूल भाषा में)
Concept and Reasoning
At standstill a single-phase stator field can be resolved into equal forward and backward rotating fields. Their starting torques are equal and opposite, giving zero net starting torque; hence the motor is not self-starting. Both assertion and reason are true and the reason correctly explains the assertion: option A.
Calculation / Key Relation
At standstill: Tf=Tb in opposite directions → Tnet=0
Exam Takeaway
Single-phase induction motor needs an auxiliary starting means because forward/backward torques cancel at rest.
Common Mistake
After the rotor starts, the two slips differ and the torques no longer cancel.
Quick Trick
Single-phase induction motor needs an auxiliary starting means because forward/backward torques cancel at rest.
નીચેના વિધાનો ધ્યાનમાં લો: વિધાન: સિંગલ-ફેઝ ઇન્ડક્શન મોટર સ્વ-પ્રારંભી (self-starting) નથી. કારણ: સ્થિર સ્થિતિમાં સિંગલ-ફેઝ વાઇન્ડિંગ દ્વારા ઉત્પન્ન ચોખ્ખું ભ્રમણશીલ ચુંબકીય ક્ષેત્ર શૂન્ય છે. આ વિધાનોમાંથી:
જવાબ અને પગલાવાર ઉકેલ
સ્થિર સ્થિતિમાં સિંગલ-ફેઝ સ્ટેટર ક્ષેત્રને સરખા આગળ અને પાછળ ફરતા ક્ષેત્રોમાં વહેંચી શકાય. તેમના પ્રારંભિક ટોર્ક સરખા અને વિરુદ્ધ હોવાથી ચોખ્ખો પ્રારંભિક ટોર્ક શૂન્ય છે; તેથી મોટર સ્વ-પ્રારંભી નથી. બંને સાચાં છે અને કારણ સાચી સમજૂતી છે: વિકલ્પ A.
વિગતવાર ઉકેલ (મૂળ ભાષામાં)
Concept and Reasoning
At standstill a single-phase stator field can be resolved into equal forward and backward rotating fields. Their starting torques are equal and opposite, giving zero net starting torque; hence the motor is not self-starting. Both assertion and reason are true and the reason correctly explains the assertion: option A.
Calculation / Key Relation
At standstill: Tf=Tb in opposite directions → Tnet=0
Exam Takeaway
Single-phase induction motor needs an auxiliary starting means because forward/backward torques cancel at rest.
Common Mistake
After the rotor starts, the two slips differ and the torques no longer cancel.
Quick Trick
Single-phase induction motor needs an auxiliary starting means because forward/backward torques cancel at rest.
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