【多选题】光伏逆变器在规定的输入直流电压允许的波动范围内,应能输出额定的电压值,一般在额定输出电压为单相220V和三相380V时,对电压波动偏差说法正确的是( )
A.
在稳定状态运行时,一般要求电压波动偏差不超过额定值的±5%;
B.
在负载突变时.电压偏差不超过额定值的±l0%;
C.
在正常工作条件下,逆变器输出的三相电压不平衡度不应超过8%;
D.
输出的电压波形(正弦波)失真度一般要求不超过5%;
E.
逆变器输出交流电压的频率在正常工作条件下其偏差应在1%以内。
【简答题】已知向量 =(2m+1,3), =(2,m),且 ∥ ,则实数m的值是( )。
【简答题】已知向量 = (6 , 2 ) , = ( - 3 , k ) , 且 ∥ , 则 k = ________. 2.已知向量 = (2 , 1 ) , = (3 , m ) , 且 3 = 2 , 则实数 m = ________.
【单选题】已知向量 =(-1,3), =(3,m),且这两个向量垂直,则m=( )
【单选题】已知向量 m , n 的夹角为 π 6 ,且| m |= 3 ,| n |= 2 ,则| m - n |=( )
【简答题】某机床电路的负载为照明灯 36V , 30W ;控制电路中 3 个接触器参数均为为 36V 、 18W 、功率因数 0.6 ; 2 个继电器为 36V 、 20W 、功率因数 0.5 。可接电源为三相四线制机床供电线路,线电压 380V ,相电压为 220V 。三个备选变压器的参数为: ( 1 )备选变压器 1 : BK-200 (一次电压 380 ,二次电压 36V ,额定容量 200VA );...
【简答题】网络营销课程设计指导书.docx “一院一专业一课程一成果”申报表(骆宇明).xls
【单选题】已知向量 a =( 3 ,1 ),向量 b =(sina-m,cosa),a∈R且 a ∥ b ,则m的最小值为( )
【单选题】已知向量 =(m-2,m+3), =(2m+1,m-2),且这两个向量的夹角大于90°,则实数m的取值范围为 [ ]
【单选题】The writing of the Constitution of the United States is an act of such genius that philosophers still wonder at its accomplishment and envy its results. Fifty-five typical American citizens met and ar...
A.
The Constitution, one of the greatest documents of the world, was written by fifty-five men of varying talents and backgrounds.
B.
The Constitution owes its greatness to the fact that it has never changed in a changing world.
C.
The Constitution was written by many people working together cooperatively.
D.
The Constitution was written by many people, all of whom were thinkers of the highest order.