High-frequency current

The unbalanced voltage will produce an additional rotor current at nearly twice the supply frequency. For example, for a 2% slip, i.e. a slip of 1 Hz, the negative sequence stator current, due to an unbalanced supply voltage, will induce a rotor current at a frequency of (2/- 1) = 99 Hz for a 50 Hz system. These high-frequency currents will produce significant skin effects in the rotor bars and cause high eddy current and hysteresis losses (Section 1.6.2(A-iv)). Total rotor heat may be represented by... 

A high frequeney eapaeitor eould also be plaeed in parallel with the larger eapaeitors. This is beeause the aluminum eleetrolytie and tantalum eapaeitors eannot absorb the very high frequency current components being presented to them. A. 01 or. 1 pF ceramic capacitor is well suited for this purpose. 

Noise sources are part of noise loops which are printed circuit board connections between high-frequency current sinks and current sources. Following the PC board design practices in Section 3.14 will help greatly in reducing the radiated RFI. Appreciation of the high-frequency characteristics of the common components and PC boards is needed. 

Metals which are subject to oxidation or attack by nitrogen can be sprayed in a closed system so that air is exluded. The heat necessary to melt the wire is produced by current generated in the wire itself by high-frequency currents flowing in small water-cooled coils. By this means, titanium, niobium and even uranium, can be sprayed without gaseous contamination. 

Figure 5-6 The Area that Is Sought to Be Minimized by the High-frequency Current Components... 

A thoughtless cut in the Ground Plane can divert the return current away from its preferred path (underlying the forward trace), thereby increasing the area of the enclosed high-frequency current loop and therefore also the inductance... 

In a Flyback, the high-frequency current loop encloses the transformer secondary, the output diode, and the output capacitor. This loop must be minimized as far as possible. 

Kam Y. Lau and Amnon Yariv, High-Frequency Current Modulation of Semiconductor Injection Lasers... 

Polyethylenes have very weak loss factors, about 1-10 x lO " and do not heat up under high-frequency current. They cannot be welded by this technique. 

EVAs have higher loss factors, about 200 x 10 high-frequency current allowing HE welding. 

PVCs are good insulators even in a wet environment, with fair dielectric resistivities and rigidities, and rather high loss factors. Resistivity decreases when the temperature rises. PVCs heat up under high-frequency current and microwaves. 

PVC-C has a high loss factor, about 250 x 10 for example, and heats up under high-frequency current. It is weldable by this technique. 

ABS grades have loss factors in the range of 20-160 x 10 " and are not generally welded under high-frequency current. 

Welding is easy by the thermal processes and by ultrasound but is not possible by high-frequency current. 

Chimlnd, Bruxelles, Belgium 3(1954) CA 50, 7479(1956)(Detn of N content in NC) 26)J. Tranchant, Ibid 3(1954) CA 51, 1607(1957) (Titanometric detn of N content in NC) 27)P. Miaud, MP 37, 465-97( 1955)(Detn of water in NC cakes by means of high-frequency current) 27)H.Stalcup R.Williams, AnalChem 27, 543-6 (1955)(Volumetric detn of NC NGu by transnitration of salicylic acid) 28)Ott vol 5, part 3(1955), 1394(Detn of viscosity of NC) 1407(Detn of N content) 1411-13(Stability tests) 1414-15(Detn of impurities, such as ash, acidity, alkalinity, sulfur chlorides in NC) 14l6(Detn of density) 29)T.C.Castorina, PATR 2107(1955XRadiometric method for detn of sulfate in crude NC) 30)E.Thonert F.Lobato, Explosivst 1955, 109-13 CA 51, 9160(1957)... 

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