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Current transformers system harmonics

A. Current Variability and Harmonics. The function of a rectifier system is to convert a power supply received as alternating current into the direct current required by the cells. There may be a reduction in voltage through transformers prior to the rectifiers, but this is outside the scope of the present discussion. Within the rectifier system, there will be some reduction in voltage to match the varying demands of the... [Pg.719]

A capacitor bank will represent reducing impedance to currents of increasing frequency. Such reducing impedance, if matched with a similarly increasing inductance impedance of a transformer or a supply system, can cause a resonant condition. In plants where equipment produces harmonic current, a full survey of the installation is recommended prior to installation of the capacitors. [Pg.222]

The EU drug approval process is working toward a harmonized FDA-type system. The transformation is not yet complete, however, and currently the EU has two drug approval systems in place. [Pg.573]

These harmonics will cause two secondary problems. Firstly, the harmonic currents will flow in cables, transformers and generator windings and in so doing will immediately produce harmonic volt-drops in these series circuits. This in turn will cause the voltages at various points in the system to contain harmonic components, e.g. either side of a transformer, at motor control centres and... [Pg.386]

In order to obtain the full benefit of harmonic cancellation the two bridges must be controlled in a common manner. The control system will enable the fundamental current in both supply lines of the same phase to be in-phase, i.e. the star primary line current must be in-phase with the delta primary line current. See Reference 12, Chapter 3 which emphasises this aspect. The controlled firing of the delta-star bridge T cancels the 30° degree phase shift of the transformer. From the Fourier analysis point of view this can be achieved by adding a + 30° phase shift to the delta primary line current. [Pg.418]

When installing multiple transformers in parallel, one must ensure that their impedances are equal. If this is not so, sharing of the load is unequal and there will be circulating currents between adjacent transformers. These currents directly result in a loss of efficiency, which can lead to early failure, faulty power metering, and a loss in reliability. In the special case of rectifier transformers, the current in each is dictated by the rectifier control systems, but if they have been given different phase shifts to minimize harmonic distortion (Section 8.3.1.3), it is again necessary to ensure that their impedances are equal. [Pg.717]


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See also in sourсe #XX -- [ Pg.485 ]




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