IEEE C37.011-2019 pdf free download

IEEE C37.011-2019 pdf free download.IEEE Guide for the Application of Transient Recovery Voltage for AC High-Voltage Circuit Breakers with Rated Maximum Voltage above 1000 V.
The choice between the three-phase grounded and three-phase ungrounded condition is accomplished by choosing the value of the first-pole-to-clear factor k,, in calculating the TRV peak. For ungrounded systems. which are often found at lower rated voltages, the value of k,, is 1.5. For effectively grounded systems. which are the norm at higher rated voltages, the value of k,, is I .3. The tables of preferred ratings in IEEE Std C37.04 include the option of both the first-pole-to-clear factors at 100 kV and above.
The waveform of the transient recovety voltage as a function of lime varies according to the arrangement of the actual circuit. The TRV waveform starts at zero volts and zero time at the point in time when the current conies down to zero and is interrupted. The TRV then increases at sonic rate reaching a peak value after which the TRV reduces and is damped out. Actual TRV waveforms observed in a power system can be as simple as a single-frequency oscillation produced by a lumped parameter R-L-C circuit, or it can be more complicated, with various oscillatory components and traveling wave reflections.
For the purposes of standards for high-voltage circuit breakers, these TRV waveforms are described in simplified terms with sonic straight lines called reference lines. The first reference line is horizontal and tangent to the TRV waveform at only one point and does not intersect or contact the waveform at any other points. This line then provides the upper bound to the TRV magnitude. Another reference line starts at the origin with zero volts at zero time and increases with some positive slope: it is tangent to the TRV waveform at only one point. In this way. the sloped line is also an upper boundary that the TRV waveform never crosses. These lines then in combination form an upper boundary that the actual TRV waveform never exceeds. A voltage and a time pair define the point of intersection of the horizontal line and the sloped line. The voltage and time values are called parameters. The voltage and time pair also define the upper end of the sloped straight reference line segment. The intersection of the straight lines always occurs at a point in time sooner than the point at which the actual TRV reaches its peak. For two straight lines, one sloped and one horizontal, two parameters, a voltage and a time, are enough to define the intersection of the two lines and to specif’ the TRV envelope. Some TRV waveshapes start with an exponential rise and then a 1-cosine rise to the peak as defined in older IEEE standards. For these wavcshapcs, there are three straight lines that form the envelope in which two of them are tangent to the maximum rate of rise on the two different rising slopes, and the third is tangent to the peak. For three straight lines, two sloped and one horizontal, four parameters. two voltages and two times. are required to define the two intersection points.
Although Iwo straight lines work well for a simple, single-frequency waveform, a third line segment is useful for more complicated TRV waveforms where returning traveling waves describe parts of the TRV envelope.IEEE C37.011-2019 pdf free download.