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This post was last edited by Wang Tianze on 2015-11-17 at 19:44. 25. A electric heater connected to a 10V DC power supply generates a certain amount of thermal power. If it is connected to an AC power supply so that the heat power generated is half that in the DC case, then the maximum voltage of the AC power supply is (D). A、7.07V B、5V C、14V D、10V 26. There are several low-voltage electrical devices such as fuses, automatic switches, contactors, thermal relays, and control relays; each of them belongs to (C). A. Fuses, automatic switches, and thermal relays belong to low-voltage protection devices ； Contactors, control relays, and automatic switches belong to low-voltage control electrical appliances. B. Fuses, automatic switches, and control relays belong to low-voltage protection electrical appliances ； Contactors and thermal relays belong to low-voltage control electrical appliances; fuses and control relays belong to low-voltage protection electrical appliances ； Contactors, automatic switches, and thermal relays belong to low-voltage control electrical appliances. Fuses and automatic switches belong to low-voltage protection electrical appliances ； Contactors, thermal relays, and control relays belong to low-voltage control electrical devices; they are turned off
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25. A electric heater connected to a 10V DC power supply generates a certain heat power. If it is connected to an AC power supply so that the heat power generated is half that in the DC case, then the maximum voltage of the AC power supply is (D). A、7.07V B、5V C、14V D、10V 26. There are several low-voltage electrical devices such as fuses, automatic switches, contactors, thermal relays, and control relays; each of them belongs to (C). A. Fuses, automatic switches, and thermal relays belong to low-voltage protection devices ； Contactors, control relays, and automatic switches belong to low-voltage control electrical appliances. B. Fuses, automatic switches, and control relays belong to low-voltage protection electrical appliances ； Contactors and thermal relays belong to low-voltage control electrical appliances; fuses and control relays belong to low-voltage protection electrical appliances ； Contactors, automatic switches, and thermal relays belong to low-voltage control electrical appliances. Fuses and automatic switches belong to low-voltage protection electrical appliances ； Contactors, thermal relays, and control relays belong to low-voltage control electrical appliances
25. A electric heater connected to a 10V DC power supply generates a certain heat power. If it is connected to an AC power supply so that the heat power generated is half that in the DC case, then the maximum voltage of the AC power supply is (D). A、7.07V B、5V C、14V D、10V 26．There are several low-voltage electrical devices such as fuses, automatic switches, contactors, thermal relays, and control relays; each of them belongs to ( C ). A. Fuses, automatic switches, and thermal relays belong to low-voltage protection devices ； Contactors, control relays, and automatic switches belong to low-voltage control electrical appliances. B. Fuses, automatic switches, and control relays belong to low-voltage protection electrical appliances ； Contactors and thermal relays belong to low-voltage control electrical appliances; fuses and control relays belong to low-voltage protection electrical appliances ； Contactors, automatic switches, and thermal relays belong to low-voltage control electrical appliances. Fuses and automatic switches belong to low-voltage protection electrical appliances ； Contactors, thermal relays, and control relays belong to low-voltage control electrical appliances
C. C.....................................
7.07 V. Since the average value of alternating current is the peak value divided by square root 2, this equals 1.414 A. Fuses, automatic switches, and thermal relays are types of low-voltage protection devices； Contactors, control relays, and automatic switches belong to low-voltage control electrical devices. Fuses and thermal relays are used for overcurrent protection; they automatically disconnect when the current exceeds their set limit for a certain period of time, and it is necessary to replace them or reset them (some thermal relays reset automatically after a certain time). Automatic switches have various functions, such as quick-break protection, overcurrent protection, and undervoltage protection. Quick-break protection is a type of protective mechanism, while overcurrent protection relies on detection for control, making it a control-type protection mechanism. Contactors and intermediate relays also fall under control-type protection mechanisms, requiring external signals to be activated
25. A electric heater connected to a 10V DC power supply generates a certain heat power. If it is connected to an AC power supply so that the heat power generated is half that in the DC case, then the maximum voltage of the AC power supply is (D). A、7.07V B、5V C、14V D、10V 26．There are several low-voltage electrical devices such as fuses, automatic switches, contactors, thermal relays, and control relays; each of them belongs to ( C ). A. Fuses, automatic switches, and thermal relays belong to low-voltage protection devices ； Contactors, control relays, and automatic switches belong to low-voltage control electrical appliances. B. Fuses, automatic switches, and control relays belong to low-voltage protection electrical appliances ； Contactors and thermal relays belong to low-voltage control electrical appliances; fuses and control relays belong to low-voltage protection electrical appliances ； Contactors, automatic switches, and thermal relays belong to low-voltage control electrical appliances. Fuses and automatic switches belong to low-voltage protection electrical appliances ； Contactors, thermal relays, and control relays belong to low-voltage control electrical appliances
25. A electric heater connected to a 10V DC power supply generates a certain heat power. By connecting it to an AC power supply so that the heat power generated is half that in the DC case, the maximum voltage of the AC power supply is (D, 10V). 26. There are several types of low-voltage electrical devices such as fuses, automatic switches, contactors, thermal relays, and control relays; each of them belongs to (C. Fuses and control relays are low-voltage protection devices) ； Contactors, automatic switches, and thermal relays belong to low-voltage control electrical appliances.
D, 10V; C, fuses and control relays belong to low-voltage protection appliances； Contactors, automatic switches, and thermal relays belong to low-voltage control electrical appliances