Positive-sequence current

While conducting the test the negative sequence voltage should be less than 0.5% of the positive sequence component. In terms of current, the negative sequence current should not exceed 2.5% of the positive sequence component of the system current. Measurement of any one of the components will be adequate. 

Figure 4.7d shows the seventh harmonic current phasors. The seventh harmonics have the same phase sequence as the fundamental and are positive sequence harmonics. 

The Hertzsprung-Russell diagram is a snapshot of a group of stars at some given moment in time. It shows what the luminosities and temperatures of those stars were at the moment that snapshot (set of observations) was taken. What the H-R diagram does not tell is anything about the evolution of those stars, the way their temperatures and luminosities have changed over time. For example, the Sun was not born with the temperature and luminosity shown by its current position on the Main Sequence. 

Modem relays include a function for detecting the negative phase sequence currents, with settings typically in the range of 10% to 50% of the nominal relay positive sequence current. High power rating motors may need a lower limit than 10%. 

Since rotor heating can be caused by excessive positive sequence current as well as the presence of negative sequence current it has become the practice in some relay designs to combine these heating causes. 

In the earlier proposed two heuristics (EDD and MS), a job is attached after the last job of current partial sequence when it is selected by the corresponding rule (due date, slack time, or objective value). They are simple to make solutions but the performances of the solutions are not likely to be very good. So we propose another heuristic, mEDD algorithm, in which a job is selected by the earliest due-date rule and it is not attached after the last job of the current sequence but inserted into a proper position between jobs in the current sequence. Though the calculation quantity of the algorithm increases, we can anticipate better performance from the algorithm. The detailed procedure is as follows ... 

Once a new method has been established or an existing one loaded, it can be implemented. A tool bar allows the implementation process and the settings of the graphics area (zoom, scales) to be controlled. The graphics area displays the analytical data as they are acquired and a status bar shows the current position in the command execution sequence. 

Fig. 4. The illustration of the reverse terminator sequencing and pyrosequencing. For reverse terminator sequencing, different dNTP is labelled with different fluorescence dye. Upwn addition of each dNTP, the reaction halts and the fluorescence is the recorded. Then the terminator and fluorescence dye of dNTP is cleaved. Subsequently, the next dNTP is incorporated and the whole process is iterated. For pyrosequendng, one single dNTP flows through with the addition of the nucleotide in the corresponding position. The release of the pyrophosphate will undergo enzymatic reaction to produce light. Therefore, the camera will record which of the fragments has this dNTP at its current position.

The second, third, and fourth distributions correspond to an aerial mode. The second is the positive-sequence mode and the third is the negative-sequence mode. However, the pattern of current distribution varies as frequency changes thus, the fourth distribution can become a negative-sequence mode at a certain frequency. 

Setup for measuring sequence currents for a cross-bonded cable (a) zero-sequence current and (b) positive-sequence current. 

The positive-sequence current is derived from Equation 3.57 ... 

The core current (I) is obtained from Equations 3.63 and 3.70. Once the core current is solved for, the positive-sequence current can be calculated as... 

Using Equation 3.65, the theoretical formula of the positive-sequence current simplifies to... 

Equation 3.71 shows that the positive-sequence current can be approximated by the coaxial mode current. It also shows that, in a manner similar to that of a cross-bonded cable, the positive-sequence current remains unaffected by the substation-grounding resistance Rg. 

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