UL 497E:2011 PDF Download

UL 497E:2011 is a standard that covers protectors for antenna lead-in conductors. These protectors are used to limit surges on the cable that connects the antenna to the receiver/transmitter electronics and are connected between the conductors and the grounded shield or other ground connection. The standard applies to various applications including antenna installations for radio and television receiving equipment, amateur radio equipment, cellular telephone towers, and WiMax or WiFi wireless networks.

The standard specifies that protectors for antenna lead-in conductors can be air gap arresters, gas tube arresters, solid-state arresters, or quarter-wave stub type devices, or a combination of these devices. They may also contain additional components such as inductors or blocking capacitors. These protectors are designed to protect equipment, wiring, and personnel from excessive potentials and currents caused by lightning.

The devices are intended to divert surge currents to earth and control the residual voltage to a suitable level. They automatically return to normal operation once the surge current has subsided. The standard does not cover the residual voltage limits or their suitability to minimize damage to connected equipment.

The standard also specifies that these protectors are investigated for their maximum discharge current capability using an 8/20 current waveform. This is the maximum impulse current the protector can withstand without affecting its surge limiting capability or creating a risk of fire, fragmentation, or electrical shock.

The standard explicitly states what it does not cover, such as lightning protective devices for secondary distribution wiring systems, antenna discharge units for radio and television appliances, lightning conductors and air terminals for building protection, as well as several other equipment covered by other standards.

Additionally, the standard includes information on components, units of measurement, and undated references to codes or standards.