Magnetization current

The application of WIROTEST 202 device with high frequency magnetic currents, will allow for simultaneous detection of parts with bums, which can occur during grinding. 

MP-suspension by automated ASTM-bulb Magnetization current by Hall-Sensor Magnetization time UV-Light intensity All Liquids (fluorescence, contamination) Process times and temperatures Function of spraying nozzles, Level of tanks Flow rates (e.g. washing, water recycling) UV-Light intensity... 

Flowever, it also necessitates a strictly constant ratio of field to frequency, over the duration of the experiment. Although the master frequency source can be held very constant by a thennostatted source, the field is always vulnerable to local movements of metal, and to any non-persistence of the magnet current. Therefore the field is locked to the frequency tlirough a feedback loop that uses continuous, background... 

The declared efficiency and power factor of a motor are affected by its loading. Irrespective of the load, no-load losses as well as the reactive component of the motor remain constant. The useful stator current, i.e. the phase current minus the no-load current of a normal induction motor, has a power factor as high as 0.9-0.95. But because of the magnetizing current, the p.f. of the motor does not generally exceed 0.8-0.85 at full load. Thus, at loads lower than rated, the magnetizing current remaining the same, the power factor of the motor decreases sharply. The efficiency, however, remains practically constant for up to nearly 70% of load in view of the fact that maximum efficiency occurs at a load when copper losses (f R) are equal to the no-load losses. Table 1.9 shows an approximate variation in the power factor and efficiency with the load. From the various tests conducted on different types and sizes of motors, it has been established that the... 

The magnetizing current, / , is a part of the motor stator current / (Figure 1.15). The rotor cun cnt is also a reflection of the active component of this stator current, as can be seen in the same figure, so that... 

This is commonly known as double phasor or phasor (vector) control. If we analyse equation (I. I) in Chapter I we will observe that 0 is a function of stator magnetizing current, /, and / is a transformation of the stator active current, /. ... 

Low at reduced speeds, due to low magnetizing current (/ ,) and correspondingly lower /,... 

Vr= rated voltage of the machine in volts, and = magnetizing current of the machine in amps. 

The no-load test is a very informative method to determine the no-load current, core and pulsation losses, friction and windage losses, magnetizing current and the no-load power factor. The test also reveals mechanical imbalance, if any, performance of the bearings, vibration and noise level of the motor. 

If there are N number of CTs connected in parallel, the magnetizing current will flow through all of them. In a CiF protection scheme all the three CTs of all the feeders being protected together will fall in parallel, while in case of a combined GF and phase fault protection scheme, only one third of these CTs will fall in parallel. The CT in the faulty circuit must be able to draw enough current to feed the magnetizing losses of all the CTs falling in parallel and the relay pickup current, The sensitivity of the differential scheme can therefore be expressed more appropriately as... 

Excessive saturation of the magnetic core reduces the value of L, and raises the magnetizing current disproportionately. say up to ten times the normal value or even more, as discussed in Section 1.2. 

By installing p.f. improvement capacitors to compensate the no-load magnetizing current of the circuit being switched (Section 23.1 3). These may be installed in the same switching circuit to switch together with the inductive load,... 

Interrupting small magnetizing currents, such as interrupting an induction motor or a transformer on no-load, a situation, when the current may lag the impressed voltage by nearly 90°. 

In armoured cables, armouring must be removed before passing the cable through the CBCT to avoid an induced e.m.f. through the armour and the corresponding magnetizing current which may affect the performance of the CT. 

At voltages lower than rated, the no-load current, / , and the magnetizing current, /, , of the motor is low and rises with the voltage. At loads lower than rated, although the p.f will diminish sharply as discussed in Section 1.8, the reactive component /, and the no-load current / [, i.e. component OA of Figure 1.16, will remain the same. 

In induction motors, the magnetizing component of the current always lags 90°. Therefore, the line current lags at all loads the magnitude depends upon the magnetizing current load. 

The excitation system provides the magnetizing current necessary for the generator to operate at the desired voltage and, when in parallel with other generators, supplies the required amount of reactive current. In modern practice the excitation system can be either brushless or static. 

In instances where a capacitor is connected directly across the terminal of the motor, the capacitor can act as a source of excitation current after the control device is opened. In order to prevent this the capacitor rating should not exceed 90 per cent of the motor no-load magnetizing current. 

Fig. 5. Effect of magnet current on electrical resistivity and transmittance of SnOj film. Microwave power of 1600 W.

Fig. 6. Effect of microwave power on electrical resistivity and transmittance of Sn02 film. Magnet current of 160 A.

In general, vertical bore magnets are usually cheaper compared with horizontal systems of the same field strength. Moreover, vertical bore magnets can provide much higher magnetic fields, currently 21 T, 900 MHz with an open bore of 52 mm, compared with horizontal bore magnets, currently 11.7 T, 500 MHz with an open bore of up to 300 mm. From the scientific point of view, the main... 

Such switches have a drawback when the magnet current is sweeping, a back electromotive force (e.m.f.) is present equal to L-dl/dt. This voltage is also present across the switch and so a current flows through the switch. 

Equations (6) and (7) define the conditions at which the current I(t) should be satisfied, in order to achieve the fastest possible transition between any two current values comprised between zero and the maximum admissible magnet current /max- When Eqs. (6) and (7) are satisfied, in fact, the power supply is exactly at the edge of saturation but does not exceed it. 

This makes it possible to program - within limits - the sign of the magnet current and thus the orientation of the magnetic field B along the magnet axis. 

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