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These power pulsations tend to cause increased mechanical noise in transformer and motor laminations due to magnetostriction and torsional vibration in generator and motor drive shafts. Two-phase power can be derived from a three-phase source using two transformers in a Scott connection : One transformer primary is connected across two phases ...
Wiring schematic for a simplified bipolar-field Gramme-ring single-phase–to–direct-current rotary converter. (In actual use, the converter is drum-wound and uses a multipolar field.) [2] Wiring schematic for a simplified two-phase–to–direct-current rotary converter, with the second phase connected at right angles to the first [3] Wiring schematic for a simplified three-phase–to ...
An induction generator produces electrical power when its rotor is turned faster than the synchronous speed. For a four-pole motor (two pairs of poles on stator) powered by a 60 Hz source, the synchronous speed is 1800 rotations per minute (rpm) and 1500 RPM powered at 50 Hz. The motor always turns slightly slower than the synchronous speed.
Doubly fed induction generator (DFIG), a generating principle widely used in wind turbines. It is based on an induction generator with a multiphase wound rotor and a multiphase slip ring assembly with brushes for access to the rotor windings. It is possible to avoid the multiphase slip ring assembly, but there are problems with efficiency, cost ...
The circle diagram can be drawn for alternators, synchronous motors, transformers, induction motors. The Heyland diagram is an approximate representation of a circle diagram applied to induction motors, which assumes that stator input voltage, rotor resistance and rotor reactance are constant and stator resistance and core loss are zero.
In motor-generators, reverse current relays prevent the battery from discharging and motorizing the generator. Since D.C. motor field loss can cause a hazardous runaway or overspeed condition, loss of field relays [25] are connected in parallel with the motor's field to sense field current. When the field current decreases below a set point ...
For certain types of electric motors or generators to function, the coils of the rotor must be connected to complete an electrical circuit. Originally this was accomplished by affixing a copper or brass commutator or 'slip ring' to the shaft, with springs pressing braided copper wire 'brushes' onto the slip rings or commutator which conduct the current.
A motor soft starter is a device used with AC electrical motors to temporarily reduce the load and torque in the powertrain and electric current surge of the motor during start-up. This reduces the mechanical stress on the motor and shaft, as well as the electrodynamic stresses on the attached power cables and electrical distribution network ...