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The equation describing the relative motion is known as the swing equation, which is a non-linear second order differential equation that describes the swing of the rotor of synchronous machine. The power exchange between the mechanical rotor and the electrical grid due to the rotor swing (acceleration and deceleration) is called Inertial ...
Synchronous speeds for synchronous motors and alternators depend on the number of poles on the machine and the frequency of the supply. The relationship between the supply frequency, f, the number of poles, p, and the synchronous speed (speed of rotating field), n s is given by: = .
It results from small air gaps in machine design (As in Turbo generators or Cylindrical rotor Machines). Machines are tightly coupled to the grid, and their response will be fast. This reduces the machine's stability while operating on the grid and will reduce the short circuit current delivery capability (lower short circuit current), smaller ...
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.
The synchronous reactances are exhibited by the armature in the steady-state operation of the machine. [8] The three-phase system is viewed as a superposition of two: the direct one, where the maximum of the phase current is reached when the pole is oriented towards the winding and the quadrature one, that is 90° offset.
Synchronous motor and induction motor stators are similar in construction. [27] The construction of synchronous motor is similar to that of a synchronous alternator. [28] The stator frame contains wrapper plate (except for wound-rotor synchronous doubly fed electric machines). Circumferential ribs and keybars are attached to the wrapper plate.
Synchronous impedance curve (short-circuit characteristic curve), showing armature current as function of field current. The curve is obtained by rotating the generator at the rated RPM with the output terminals shorted and the output current going to 100% of the rated for the device (higher values are typically not tested to avoid overheating).
This is exactly the value estimated by the formula stated earlier. EXAMPLE: Torque applied at different diameters , K v (rpm/V) {\displaystyle K_{\text{v (rpm/V)}}} = 3600 rpm/V ≈ 377 rad/s/V , K T {\displaystyle K_{\text{T}}} ≈ 0.00265 N.m/A (each calculatable if one is known) , V = 2 v, I a {\displaystyle I_{\text{a}}} = 2 A, P = 4 W ...