Final answer:
Grounding an AC electric motor's housing and frame is essential for safety to prevent electric shocks from induced voltages. Grounding maintains the induced emf near zero and creates a safe path for potential leakage currents.
Step-by-step explanation:
The grounding of an AC electric motor is crucial for safety reasons. Electromagnetic induction can cause a voltage, or an electromotive force (emf), to be induced on the case of an appliance, including the housing and the frame of electric motors. If the case is grounded, this induced emf is kept near zero, which helps to prevent electric shock. However, if the case is not grounded, the voltage can be large enough to pose a hazard. Grounding creates a safe path for leakage current that could otherwise shock someone who touches the ungrounded case.
Importance of Grounding in Electric Motors
Thus, while both AC and DC motors can potentially induce an emf in their casing, grounding is generally more associated with AC motors because AC currents are more likely to produce significant induced voltages due to their changing nature. For instance, in an electric clothes dryer, the heating coils can be counter-wound to cancel magnetic fields and reduce mutual inductance with the case—a strategy that outlines the concerns with induced currents in household appliances.
In conclusion, grounding the case and frame of an AC electric motor is not just a requirement; it\\\'s a safety measure to prevent electric shocks caused by induced voltages and to ensure proper functioning of the appliance it powers.