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Earthing of VSAT dishes
Former Community Member
I am trying to apply the principles of BS 7671 to VSAT installations in Africa. My chief concern is the connection of the VSAT dish to the electrical supply provided by the customer. The standard practice I've adopted is shown in the attached sketch. The metallic parts of the dish are connected with copper conductors and then to an earth spike (or spikes) near the dish foundations. The earth cable is then run (either in a conduit of buried) to the equipment building. At the entry to the building, the earth cable is used by surge arrestors fitted to the RF cables. The earth cable then runs to an earth bar fitted into the equipment cabinet. The mains supply to the equipment is supplied by the customer, the earth of which is also connected to the cabinet's earth bar. The power supplied by the customer may be from a generator 100% of the time, or more like comes from the town's municipal supply, These supplies are often erratic so a back-up generator is often in use, and as a matter of course we always fit an on-line UPS. Is this approach sensible? Thanks for any assistance.
Thanks for the pointer I'll try the other forum. The supplies are mainly TT, but some very remote sites are powered by a local generator almost full time. The protective devices are usually RCDs. The earthing is to give some protection in case of lightning. However, if the location is very prone to electrical storms an air terminal on a near-by structure is usually also provided. This will have it's own earthing system. The dishes are usually ground based. The class of the power supply is difficult to determine as the indoor equipment comprises six or seven modules each with their own mains supply. The equipment mounted on the dish usually gets its power from the RF coax cables. However, sometimes the dish mounted amplifier (BUC) is 240v powered, either with an SWA cable run into the unit, or via a 240v ac/48v dc power supply mounted on the antenna mount.
Brian
Hello Brian, you will get some replies soon when the experts get back from the pubs and night clubs.
Thanks for the pointer I'll try the other forum. The supplies are mainly TT, but some very remote sites are powered by a local generator almost full time. The protective devices are usually RCDs. The earthing is to give some protection in case of lightning. However, if the location is very prone to electrical storms an air terminal on a near-by structure is usually also provided. This will have it's own earthing system. The dishes are usually ground based. The class of the power supply is difficult to determine as the indoor equipment comprises six or seven modules each with their own mains supply. The equipment mounted on the dish usually gets its power from the RF coax cables. However, sometimes the dish mounted amplifier (BUC) is 240v powered, either with an SWA cable run into the unit, or via a 240v ac/48v dc power supply mounted on the antenna mount.
Brian
Hello Brian, you will get some replies soon when the experts get back from the pubs and night clubs.
