Distribution voltage U e=220V The design socket circuit adopts BV-2*.5 wire, BVR-1*2.5PE; Check the table: RO = 8.7 ohm / KM; XO = 0.127 / KM; The maximum distribution distance in the design plane is 50 meters, so the other circuit L=100 meters, the circuit breaker is C65 type distribution type circuit breaker, and the contact resistance RZ=1.3 milliohms; Second, the calculation formula Id=Ue/ZxI∑ Where Ue is the rated loop voltage and ZxI∑ is the total loop impedance Third, protection calculation 1) Calculate ZxI∑ ZxI∑= √ (0.0013+100*0.0087)^2+(100*0.000127 ^2) 2) Calculate single-phase ground fault current Id (TN system) Id=Ue/ZxI∑=220/0.871=253(A) 3) Checking According to Schneider C65 miniature circuit breaker type 2 curve (distribution type), when the short-circuit current is 4-7 times of the rated current of the circuit breaker, it will act instantaneously. The socket circuit breakers used in the design are all 065-10A/1P, ie Ie=10A; Therefore, the single-phase ground fault current action multiple is m=Id/Ie=253/10=25.3 (times) to ensure instantaneous action, and the trip time is t=0.02 second, which fully meets the requirements of the specification. Dry Type Distribution Transformer
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Dry type transformers are widely used in local lighting, high-rise buildings, airports, terminals, CNC mechanical equipment and other places. Simply speaking, dry type transformers refer to transformers whose core and windings are not immersed in insulating oil. Dry Type Distribution Transformer,Non encapsulated transformer,Air Cooling Transformer,Dry Power Transformer,Dry type epoxy resin transformer Henan New Electric Power Co.,Ltd. , https://www.newelectricpower.com
=√ 0.759+0.00016
=0.871 (Europe)
Cooling methods are divided into natural air cooling (AN) and forced air cooling (AF). In case of natural air cooling, the transformer can operate continuously for a long time under rated capacity. In case of forced air cooling, the output capacity of transformer can be increased by 50%. It is applicable to intermittent overload operation or emergency overload operation; Due to the large increase of load loss and impedance voltage during overload, it is in a non economic operation state, so it should not be in a long-term continuous overload operation.
How to calculate the socket loop protection
First, the calculation conditions