Generally applicable rules for connecting HV limiters
Four rules, which can be applied generally to protection in VN networks, follow the above characteristics:
- The overvoltage limiters, and the device that is to be protected must be connected to a common earthing system. The galvanic interconnection between the earthing terminals of the limiters and the earthing of the protected device must be as short as possible.
- The total length of conductors a and b connecting the limiters to the protected device must be as short as possible.
- It is always recommended that conductor b should be as short as possible, or at least shorter than conductor a.
- Strip conductors are more suitable for connections than those with circular cross-sections, for with the same cross-section strip conductors have smaller inductance and pulse losses of overvoltages in them are smaller. The minimum size of a connecting conductor is 6 mm. The minimum width of a strip conductor is 12 mm.
Above all, the reason for installing overvoltage limiters is to prevent any possible damage. A seemingly considerable cost of such protections tends to be only a fraction of a percent of the acquisition value of the technology protected, and a negligible sum for possible damage caused by the breakdown, and/or the destruction of technological equipment. Unprotected electric distribution systems, computers, and data networks always pose a considerable risk to their users.