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It is also known as short-circuit test (because it is the mechanical analogy of a transformer short-circuit test), [1] locked rotor test or stalled torque test. [2] From this test, short-circuit current at normal voltage , power factor on short circuit, total leakage reactance , and starting torque of the motor can be found.
Since we have shown that the neutral current is zero we can see that removing the neutral core will have no effect on the circuit, provided the system is balanced. Such connections are generally used only when the load on the three phases is part of the same piece of equipment (for example a three-phase motor), as otherwise switching loads and ...
This no-load current is very small and because the copper loss in the primary is proportional to the square of this current, it is negligible. There is no copper loss in the secondary because there is no secondary current. [1] The secondary side of the transformer is left open, so there is no load on the secondary side.
Per-unit quantities are the same on either side of a transformer, independent of voltage level; By normalizing quantities to a common base, both hand and automatic calculations are simplified. It improves numerical stability of automatic calculation methods. Per unit data representation yields important information about relative magnitudes.
Direct torque control (DTC) is one method used in variable-frequency drives to control the torque (and thus finally the speed) of three-phase AC electric motors.This involves calculating an estimate of the motor's magnetic flux and torque based on the measured voltage and current of the motor.
A Scott-T transformer or Scott connection is a type of circuit used to produce two-phase electric power (2 φ, 90 degree phase rotation) [1] from a three-phase (3 φ, 120 degree phase rotation) source, or vice versa. The Scott connection evenly distributes a balanced load between the phases of the source.
A high-voltage current transformer may contain several cores, each with a secondary winding, for different purposes (such as metering circuits, control, or protection). [7] A neutral current transformer is used as earth fault protection to measure any fault current flowing through the neutral line from the wye neutral point of a transformer.
Cutaway view of an LVDT. Current is driven through the primary coil at A, causing an induction current to be generated through the secondary coils at B.. The linear variable differential transformer (LVDT) – also called linear variable displacement transformer, [1] linear variable displacement transducer, [2] or simply differential transformer [3] – is a type of electrical transformer [4 ...