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| The classification and selection of low voltage electrical apparatus |
| Many types of low-voltage electrical appliances, there are many kinds of classification methods.
According to the movement can be divided into 1:
(1) manual appliances -- rely on direct manipulation force to switch electrical appliances, such as knife switch, button switch.
(2) automatic appliances -- rely on changes in instructions or physical quantity and automatic action appliances, such as contactors, relays etc..
2 can be divided according to use:
(1) low voltage control electrical appliances -- mainly plays a control role in the low-voltage power distribution system and power equipment, such as knife switch, low voltage circuit breaker.
(2) low voltage protection apparatus -- mainly play a protective role in the low-voltage distribution system and power equipment, such as a fuse, thermal relay.
3 according to the species can be divided into:
Knife switch, knife switch, fuse, low voltage circuit breaker, contactor, relay, master appliances and automatic switch etc..
Equipment selection
The selected 1 design of low-voltage electrical appliances, shall be in accordance with the current national standards, and shall comply with the following requirements.
1) rated voltage appliance shall be compatible with the nominal voltage where the loop
2) calculation of current electrical current rating shall be not less than the local loop
3) rated frequency appliances should be located and adapted to the frequency of Port Road
4) appliances should adapt to the environment conditions
5) appliances should meet the short-circuit conditions of dynamic stability and heat stability requirements. To disconnect the electrical short-circuit current, short circuit conditions should meet the on-off ability.
2 checking appliances under short circuit conditions of the on-off ability, should use the installation expected effective value periodic component of short-circuit current, when the short circuit point near the connected motor rated current and short-circuit current of more than 1%, should be included in the influence of motor feedback current. | | | author: Published at: 2015/2/5 10:33:04 |  |
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