Magnetic field calculations at an observation point are to b

Magnetic field calculations at an observation point are to be conducted for the 330 kV tower analysed previously in Part 3, Figure P3_1: Calculate the resultant magnetic field at a measuring point 1 metre off the ground on the centerline of the double circuit transmission line. Assume each circuit is carrying a balanced load of 1100 Amps. The transmission line is reverse-phased. Assume that the conductor is operating at a temperature of 50 degrees C, and sag on flat terrain of 18 meters. One circuit is removed for maintenance shifting all load load to the remaining circuit in-service. Re-calculate the resultant magnetic field at a measuring point 1 metre off the ground on the centreline of the double circuit transmission line. Assume maximum temperature of the remaining circuit is at the maximum of 90 degrees, with a sag of 2 A metres The phasing of both circuits is later reconfigured to a super-bundle arrangement and are both in-service. Re-calculate the resultant magnetic field at a measuring point 1 metre off the ground on the centreline of the double circuit transmission line assuming the loading per circuit and sag conditions utilised in (a) above. Comment on your observations from calculations in (a) to (c). If a site measurement and B-Field exposure assessment is undertaken for a local stakeholder request, what connectivity configuration(s) from the above (or any other of relevance to satisfy an assessment against ICNIRP 2010 guidelines) should be considered in the interpretation provided to the stakeholder. The iterative nature of this Question is probably best undertaken with a partial spreadsheet implementation. If implementing this problem in a spreadsheet, the steps in Part (a) should clearly show the equations used and the expanded working followed to arrive at the Magnetic Field resultant. To arrive at subsequent answers for Parts (b) and (c), these may be done in a spreadsheet but please clearly identify the relevant data inputs and assumptions made

Solution

a) H = I/2*pi*r

1100/2*pi*(18 -1)

= 9 mA