[James_H._Harlow]_Electric_Power_Transformer_Engin(BookSee.org)
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FIGURE 2.6.29 5-kV three-phase/four-wire metering rack with 3 VT and 3 CT. (Photo courtesy of Kuhlman <strong>Electric</strong><br />
Corp.)<br />
FIGURE 2.6.30 34.5-kV three-phase oil-filled metering unit. (Photo courtesy of Kuhlman <strong>Electric</strong> Corp.)<br />
products, 5 kV through 34.5 kV (Figure 2.6.29), but they are also available in oil-filled units (Figure<br />
2.6.30). It is a prewired assembly with all of the elements’ secondary leads connected to a common<br />
junction box for easy access. The elements can be in any combination needed to provide accurate energy<br />
measurement. For three-phase/four-wire installations use either 2 1 / 2- or 3-element arrangements, and<br />
for three-phase/three-wire installations use 2-element arrangements. There are even single-phase assemblies<br />
available for special applications.<br />
When measuring energy usage for the purposes of revenue billing, and knowing the RCF and phaseangle<br />
readings of each element, the watts or watt-hours can be corrected by multiplying the reading by<br />
the product of [TCF CT ][TCF VT ].<br />
2.6.4.15 New Horizons<br />
With deregulation of the utility industry, the buying and selling of power, the leasing of power lines, etc.,<br />
the need for monitoring power at the transmission and distribution level will increase. There will be a<br />
need to add more metering points within existing systems beginning at the generator. The utilities will<br />
want to add this feature at the most economical cost. The use of window-type slipover CTs for revenue<br />
metering will drive the industry toward improved performance. The need for higher accuracies at all<br />
levels will be desired and can be easily obtained with the use of low-burden solid-state devices. Products<br />
will become more environmentally safe and smaller in size. To help the transformer industry fulfill these<br />
needs, steel producers will need to make improvements by lowering losses and increasing initial permeability<br />
and developing new composites.<br />
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© 2004 by CRC Press LLC<br />
© 2004 by CRC Press LLC