In a DC machine the Frame holds the field poles and provides a magnetic path between them.

Question

BlackTom AI · Accepted Answer

The frame (also called the yoke) of a DC machine serves as the outer structure that supports and holds the field poles and forms a part of the magnetic circuit that returns flux between poles.

Relevant knowledge points and concepts:
- Main parts of a DC machine include the frame (yoke), field poles (pole cores and pole shoes), armature core, commutator, and air gap.  
- The magnetic circuit requires a high-permeability path for flux to flow from one pole to the next; the frame/yoke is the return path.  
- The frame also provides mechanical support and protection for internal components and helps dissipate heat.

Step-by-step reasoning:
1. Identify the component that physically “holds the field poles.” The outer structure which bolts the poles in place and encloses the machine is the frame (yoke). This is a mechanical fact about machine construction.  
2. Identify which element “provides a magnetic path between them.” In the magnetic circuit, flux leaves a field pole, crosses the air gap through the armature, and returns through the frame/yoke to the opposite pole. Thus the frame is the magnetic return path.  
3. Material and function confirm this: frames are made of cast iron or steel with good magnetic permeability so they can carry magnetic flux with minimal reluctance, fulfilling the “magnetic path” role.

Why the correct answers are correct:
- “Frame” is correct for the first blank because it is the structural part that holds the field poles in place.  
- “magnetic path” is correct for the second blank because the frame serves as the low-reluctance return route for flux between poles.

Why other plausible choices would be incorrect:
- “Armature” does not hold the field poles; it rotates inside and contains conductors.  
- “Commutator” is a rotating electrical switching device, not a structural or magnetic return element.  
- “Field winding” or “pole shoe” are parts of the field poles themselves, not the outer structure that provides the inter-pole return path.

Conclusion: The frame (yoke) holds the field poles and provides the magnetic path between them, which matches the provided answers: "Frame" and "magnetic path."

In a DC machine the Frame holds the field poles and provides a magnetic path between them.多重下拉选择题

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