Antenna & Feeder Line Structure at HPT Faqeerabad:

[Ch. Zeshan YousafParticipant]

Antenna Construction:

The mast has a trihedral lattice-type body with a base of 2.2 m in section, supported with four tiers of guys, arranged in three planes. The mast body is erected on an armoured 03-2100 type base insulator equipped with special discharge arresters. Maximum permissible insulator voltage is 100 kV.
The antenna screen has dimensions as follows:
Diameter – 15 m
Number of wires – 15
Diameter of each wire – 12 mm
The screen is insulated against the ground and the mast body with the aid of insulators, cut in each vertical wire at the ground and at the certain elevation corresponding to the top elevation of the screen.
Taking into consideration dielectric strength, the insulation is effected with the help of chains of four AC-2500-300 type rod insulators, each being rated for operating voltage up to 30 kV.
The antenna design provides for possibility of switching the screen over to two heights: 0.4 H and 0.33 H.
This is obtained in the following way:
The chains of four rod insulators are cut in the wires screen at two elevations of 85 m and 104 m.
In case of operation with the screen height of 0.4 H, the insulator chains being in wires at elevation 85 m are closed with special bridges.
At the operation with the screen height of 0.33 H, these bridges are opened and special detachable bridges are connected to the mast body.
The mast guys are sectionalized with insulators. The sectionalization has been carried out taking into account the condition with power of 1000 kW over a wave range of 200 to 600 m.
Maximum length of the guy section makes 1/4 the minimum operating wavelength of the antenna. 1 μ0 and 2 μ0 type guy insulators, ensuring maximum voltage of 20 kV and 40 kV, respectively, are utilized for sectionalization of the mast guy. The insulators are equipped with discharge arresters and are extinguishing chokes, quenching the discharge in the arrester gap, the transmitter being switched on.

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