The correct answer is: D. At the slot edge where coil enters or comes out of the slot.
The running winding of a single phase motor is the winding that is connected to the power supply. The winding is made up of a number of turns of wire that are insulated from each other. The turns of wire are then wound around a core, which is usually made of iron. The core helps to concentrate the magnetic field produced by the current flowing through the winding.
When the motor is turned on, the current flowing through the running winding creates a magnetic field. This magnetic field interacts with the magnetic field produced by the stator winding, which is the winding that is fixed in place. The interaction of these two magnetic fields creates a torque that causes the motor to rotate.
If the running winding is grounded, this means that there is a direct connection between the winding and the ground. This can happen if there is a break in the insulation of the winding, or if there is a foreign object that comes into contact with the winding.
If the running winding is grounded, the motor will not work. This is because the current that flows through the winding will flow through the ground instead of through the stator winding. This will prevent the motor from creating a torque.
The most probable location of the ground is at the slot edge where coil enters or comes out of the slot. This is because the insulation at this location is often the thinnest. Additionally, this location is where the winding is most likely to come into contact with a foreign object.
The other options are not as likely to be the location of the ground. Option A, at the end connections, is not as likely because the insulation at this location is usually thicker. Option B, at the end terminals, is not as likely because the terminals are usually insulated. Option C, anywhere on the winding inside a slot, is not as likely because the insulation at this location is usually thick enough to prevent a ground.