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The volt-ampere (SI symbol: VA, [1] sometimes V⋅A or V A) is the unit of measurement for apparent power in an electrical circuit.It is the product of the root mean square voltage (in volts) and the root mean square current (in amperes). [2]
In the power systems analysis field of electrical engineering, a per-unit system is the expression of system quantities as fractions of a defined base unit quantity. . Calculations are simplified because quantities expressed as per-unit do not change when they are referred from one side of a transformer to t
400 V low voltage secondary side distribution transformer with primary 12 kV; 200 kVA (up to 1000 kVA also common) [7] 10 3: 2 kA 10.5 kV secondary side from an electrical substation with primary 115 kV; 63 MVA [8] 9.3 kA 2.7V, Ultracapacitor short circuit current [9] 10 4: 25 kA Lorentz force can crusher pinch [10] 30 kA Typical lightning ...
In electrical engineering, the power factor of an AC power system is defined as the ratio of the real power absorbed by the load to the apparent power flowing in the circuit. . Real power is the average of the instantaneous product of voltage and current and represents the capacity of the electricity for performing
is the motor velocity, or motor speed, [2] constant (not to be confused with kV, the symbol for kilovolt), measured in revolutions per minute (RPM) per volt or radians per volt second, rad/V·s: [3]
Buck–boost transformers can be used to power low voltage circuits including control, lighting circuits, or applications that require 12, 16, 24, 32 or 48 volts, consistent with the design's secondaries. The transformer is connected as an isolating transformer and the nameplate kVA rating is the transformer’s capacity. [2]
In the case of devices that output a different voltage than the battery, it is the battery voltage (typically 3.7 V for Li-ion) that must be used to calculate rather than the device output (for example, usually 5.0 V for USB portable chargers). This results in a 500 mA USB device running for about 3.7 hours on a 2,500 mAh battery, not five hours.
The phase shift in Europe is 120°, as is the case with three-phase current. That's why we calculate 130V * √3 = 225V. A three-phase final step-down transformer is then used. One house gets phases A & B, the next house gets phase B & C, the third house gets phase A & C.