Comparison between ac motor and dc motor
Alternating current is a frequency, usually with a power supply of 50HZ (such as China) or 60HZ (such as the us), with a voltage of 110V (such as the us) and 220V (such as China). Alternating current (ac) in China to 220 v, 50 hz access to power, his 50 hz frequency, can use ordinary power frequency transformer transformer (general transformer), more convenient, and direct current (dc) want to transformer, you need to use switching power supply, the switching power supply is very expensive, so for the power grid companies, the investment is too big. In addition, due to the power of the user, the phase voltage (voltage between the fire line) is 220V and the line voltage (voltage between the two different winding wires) is 380V On the high voltage side, the normal transformer input voltage is 10KV (kv) or 20KV 35KV, which is the main class, with 20KV most. Because of the high voltage transmission, according to the P = UI that power must be, the smaller the higher the voltage, current, and the current in the conductor can pass ability, is determined by the conductor cross-sectional area
Alternating current definition: the current called alternating current, called alternating current, is called alternating current. The direction and magnitude of the current will change over time. Power plant generators is to use the power of the generator coil, each turn 180 ° generator output current will change in the direction of the time, so the size of the current will change with time for regular, this power is called "ac power". Abbreviated as AC, such as: home power. Direct current is the current in which the current direction is not present, and the current is dc Dc, dc, dc, dc, dc, dc, dc Battery and switch power supply output, we generally think that is a standard dc, and alternating dc similar to alternating current (ac), but he is not a cycle of change, but the direction of current swapping places is not periodic, for pulse dc is cyclical impact current, current direction is certain.
The advantages of a dc motor The dc motor has good starting characteristics and speed regulating characteristics The torque of dc motors is greater It's cheaper to repair. Dc motor is more energy-efficient than communication.
Such high-pressure transport means that smaller wires can be used to save costs. search And because of that, the exchange of these frequencies, 50HZ 60HZ, is less expensive. So it suits our national conditions better However, ultra-high voltage, long-distance transmission, for example, these provinces, are dc transmission, dc transmission can be more efficient use of effective area of the wire, the main is pure in impedance and affect the efficiency of ac. But dc power normally just at a distance, such as China, so in general can be more cost savings, but need to build on both ends of the rectifier and inverter equipment will ac to dc and dc to ac grid. So if it's a distance transmission, the cost is too high. Only for long-distance transmission.
