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Apr 28
2008
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Ocean Ground BedPosted by kroberts in Technology   |
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PPC-1 uses DC power feeding equipment (PFE) located in Sydney and Guam. The cable, as previously described, contains a central copper conductor which is insulated from the sea water by a layer of polyethylene. The PFEs are basically reliable and very stable high voltage DC power supplies. These devices power the submerged repeaters along the cable from Sydney to Guam. To complete the DC electrical circuit between Sydney and Guam, a sea earth return is used. This is shown in orange in the figure above.
The Ocean Ground Bed provides the connection from the PFE to the sea earth at a site normally adjacent to the landing point so that a low resistance to earth can be obtained. We typically would like to see resistances lower than 1-2 ohms for a "good" earth. The OGB itself is made up of a series of special long lasting electrodes bored 500-600 mm into the water table. In order to get the required resistance additional electrodes are installed in parallel until the required resistance is achieved.
