Magnetising current

The magnetising flux is determined by the applied voltage to the primary winding. In power transformers the current drawn from the supply to magnetise the core is only a fraction of one percent of the rated primary winding current. The core design and type of iron is specially chosen to minimise the magnetising current. 

If an induction motor is run at a frequency below its normal operating frequency, the air-gap flux will rise if the supply voltage magnitude is kept constant. The rise in flux will cause magnetic saturation in the iron circuit of the motor and this in turn will cause a very large increase in magnetising current in the branch shown in Figures 5.1 or 15.11. 

Harmonic number Stator current Rotor current Magnetising current Air-gap voltage ... 

For induction motors, the total current can be approximated by the vector sum of the torque producing component and the magnetising or flux producing component of motor current. These two current vectors are in quadrature, and as the hoist torque approaches zero, the motor current approaches magnetising current. Electrical RMS calculations for hoist motors must be based on motor current, and so the calculation based on torque current only is not accurate for induction motors, and under-estimates the induction motor current. For greatest accuracy the duty cycle must be calculated with the correct motor characteristics. 

In the case of constantly fluxed synchronous motors, the stator cmrent will follow the motor torque more closely. After adding excitation losses, the synchronous motor efficiency is still shghtly better than the induction motor. The drive inverter for a synchronous motor supplies the armature or torque producing current, compared to the induction motor apph-cation where the inverter must supply torque producing current and magnetising current In the synchronous motor application, the motor operates at unity power factor, which reduces current demand in the inverter section. As a result, there are fewer losses in the inverter and motor, and to a lesser extent fewer losses in the converter. 

In these equations, J is the physical current density. Clearly, the magnetisation density is a derived quantity. 

This is the desired result which may be substituted into the scattering amplitude formula (6). The resulting scattering formula is the same as found by other authors [5], except that in this work SI units are used. The contributions to the Fourier component of magnetic field density are seen to be the physically distinct (i) linear current JL and (ii) the magnetisation density Ms associated with the spin density. A concrete picture of the physical system has been established, in contrast to other derivations which are heavily biased toward operator representations [5]. We note in passing that the treatment here could be easily extended to inelastic scattering if transition one particle density matrices (x x ) were used in Equations (12)—(14). 

This expression indicates that it is the sum of the paramagnetic current operator and the curl of the magnetisation density,... 

Figure 28.1 Schematic plot of two output curves of a spin OFET for parallel and antiparallel magnetisation of the sonrce (S) and drain (D) contacts. Both cnrves correspond to the same valne of the gate/sonrce voltage above threshold. Thns electrically the OFET is in the ON -state. However, snhstantial current flow only occnrs for parallel magnetisation of the S and D contacts (active state).

Similarly incoherent magnetisation transfer due to chemical exchange is also not part of the current version of NMR-SIM. Only chemical shift and coupling evolution that... 

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