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This post was last edited by 3983596_FPPZ on 2018-12-1 08:45. For bk02.jpg: Rules for multiple-choice questions: 1. If the answer to each question is incorrect, participants will still receive a reward of 2 wealth points； 2. A correct answer rewards 6 wealth points ； 3. Rewards for answers are available once per person only ； 4. Each reply allows for one management rating only ； 5. The answer and its explanation will be visible after responding ； 6. The reward is valid for 48 hours. The student has won awards again; come by here every day. The electric motor that drives the pump can be started in the following ways (multiple choice): A. Direct start B. Reduced-voltage start C. Soft start (which can be considered a type of variable-frequency start) D. Quick start. Answer: ABC. It is advisable to start equipment slowly, with the speed increasing gradually; too rapid a start has three disadvantages: 1. It can damage the equipment. Since the rotational inertia of the equipment’s rotor varies, an excessive rotational inertia combined with a too-fast start can result in excessive stress on the shafts and keys. Once this stress exceeds the design safety limits, damage will occur ； 2. It can damage the motor; starting the motor too quickly, especially with pumps that have a high moment of inertia, results in high starting loads and excessive current, which can cause the motor windings to overheat rapidly, thereby reducing the motor’s lifespan or even leading to its destruction ； 3. Impact on the power grid: Starting too quickly can result in very high instantaneous currents in the motor, causing a significant strain on the power grid. This leads to problems for the electrical devices connected to the grid due to insufficient voltage. For low-power devices, direct starting as described in option A is generally used; for higher-power devices or special devices, starting methods outlined in options B and C are typically employed, and sometimes hydraulic couplings and safety clutches are used to provide cushioning. I have yet to see any example of the rapid starting method described in option D.