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Power Over Ethernet Interoperability Guide by Sanjaya Maniktala

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GR-1089 (Telcordia) Requirements
GR-1089-Core (1999) standard relates to testing of lightning and AC- power fault surges in a telecommunications central office environment. It requires “primary protection” from surges and lightning strikes at the service entrance. But there is some “let-through,” which is handled by “secondary protection.”
Primary protection is the first line of defense. It is required at a facility’s (service) entrance. Several means are employed to implement it. Carbon blocks are the oldest type of overvoltage protective device, originally used to protect against overvoltage in telephone installations. They work by forming a spark gap with two pieces of carbon in close (3 to 6 mils) proximity. The gap flashes over at around ...

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