【Daily Question: Pump Equipment】Short Answer Question, 4/17/2019
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bk12.jpg Rules for short-answer questions: 1. If the answer is incorrect, +2 wealth will be given for active participation; if the answer is somewhat reasonable but not specific enough, +5 wealth will be given; if the answer is correct, +8 wealth will be given. 2. Rewards for answers are available once per person only. 3. Each reply allows scoring for only one person. 4. The answer and its explanation will be visible after responding. 5. The reward is valid for 48 hours; no reward will be given if the deadline is exceeded. The student has won another award; come by here every day. Motors used in high-power equipment (**standardly, the power is greater than 75KW**) are often started using voltage reduction or soft starting methods. Please briefly explain the advantages of such starting methods Answer: 1. During full-voltage starting, the motor’s starting current is 7-10 times the rated current. This method of starting can reduce the impact on the power grid and electrical equipment ； 2. During full-pressure starting, the rotational components of the equipment possess a certain amount of inertia as well as pre-load from the medium, which results in the highest torque value during the starting process. This starting method helps to reduce damage to the torque-transmitting components of the equipment (such as couplings, shafts, hubs, keys, etc.).
1. During full-voltage starting, the motor’s starting current is 7–10 times the rated current. This method of starting can reduce the impact on the power grid and electrical equipment ； 2. During full-pressure starting, the rotational components of the equipment possess a certain amount of inertia as well as pre-load from the medium, which results in the highest torque value during the starting process. This starting method helps to reduce damage to the torque-transmitting components of the equipment (such as couplings, shafts, hubs, keys, etc.).
Reduce starting current to avoid tripping due to starting overcurrent
Avoid excessive voltage drops caused by motor startup, which could affect other devices that are in operation.
Less damage to the power grid due to impacts at certain times
1. Achieve smooth starting of the motor and load. 2. Reduce the impact of starting current on the power grid. 3. Protect the power grid and mechanical system
Answer: The advantages of reduced-voltage starting include simple wiring, easy maintenance, low operating and investment costs, low requirements for the operating environment, and fewer failures. Soft starting enables voltage reduction and current limiting during startup, resulting in a smoother start process with less stress on the motor and mechanical equipment. It offers comprehensive protection features, a high degree of automation, and allows for remote control.
1 No inrush current 2 Has soft stop function 3 Startup parameters are adjustable
1. When the motor starts, the machinery cannot withstand the impact torque resulting from starting at full voltage； II. When the motor starts, its terminal voltage does not meet the specification requirements ； III. When the motor starts, it affects the normal operation of other loads. Therefore, voltage reduction or soft starting is necessary; this prevents the three aforementioned effects from occurring when the motor starts, allowing it to start directly regardless of its power level