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 earthed 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 of connection of 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 connection than those with circular cross-section as with the same cross-section strip conductors have smaller inductance and pulse losses of overvoltage 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 installation of overvoltage limiters is prevention of possible damage. A seemingly considerable cost of such protections tend to be only a fraction of a per cent of the acquisition value of the technology protected and a negligible sum for possible damage caused by breakdowns and destruction of technological equipment. Unprotected electric distribution systems, computer and data networks always pose a considerable risk to their users.
One-line diagram of protection with the marking of sections of conductor a and conductor b
Connection of the limiters to the transformer
Ground plan of the earthing network of limiters at the transformer
Connection of the limiter: (a) correct connection, (b) incorrect connection