Search results
Results from the WOW.Com Content Network
For example, balanced two-phase power can be obtained from a three-phase network by using two specially constructed transformers, with taps at 50% and 86.6% of the primary voltage. This Scott T connection produces a true two-phase system with 90° time difference between the phases.
A three-phase motor is more compact and less costly than a single-phase motor of the same voltage class and rating, and single-phase AC motors above 10 hp (7.5 kW) are uncommon. Three-phase motors also vibrate less and hence last longer than single-phase motors of the same power used under the same conditions. [32]
One voltage cycle of a three-phase system. A polyphase system (the term coined by Silvanus Thompson) is a means of distributing alternating-current (AC) electrical power that utilizes more than one AC phase, which refers to the phase offset value (in degrees) between AC in multiple conducting wires; phases may also refer to the corresponding terminals and conductors, as in color codes.
The goal of a power-flow study is to obtain complete voltage angles and magnitude information for each bus in a power system for specified load and generator real power and voltage conditions. [3] Once this information is known, real and reactive power flow on each branch as well as generator reactive power output can be analytically determined.
A per unit value out of normal range is worth looking into for potential errors. Manufacturers usually specify the impedance of apparatus in per unit values. Use of the constant is reduced in three-phase calculations. Per-unit quantities are the same on either side of a transformer, independent of voltage level
Due to the low short circuit level detected by the wind generator voltage controller and the high voltage control gain, the oscillation occurred. When compared to the normal grid with high SCR, the closed loop voltage control would have a faster response under weak grid conditions.
Due to high cost of a generator, a set of sensors and limiters will trigger the alarm when the generator approaches the capability-set boundary and, if no action is taken by the operator, will disconnect the generator from the grid. [3] D-curve expands with cooling. The D-curve for a particular generator can be expanded by improved cooling.
As an example, consider the use of a 10 hp, 1760 r/min, 440 V, three-phase induction motor (a.k.a. induction electrical machine in an asynchronous generator regime) as asynchronous generator. The full-load current of the motor is 10 A and the full-load power factor is 0.8. Required capacitance per phase if capacitors are connected in delta: