Nautel XR6, Руководство по устранению неисправностей, Страница: 17 / 291

XR6/XR3 Troubleshooting Manual
Issue 3.0 2009-07-15 Page xvii
Marking hazards
Place warning signs close to any hazardous areas or systems (e.g., the feedline or the antenna system).
Make the signs large enough that they cannot be missed. Provide signage in all languages used in the
region. These signs are intended not only for authorized personnel, but also for emergency
responders or accidental trespassers.
Qualifying site personnel
Make sure that personnel who have access to the site are qualified to work around electronics and
high voltage systems.
Ac power protection
You should take steps to protect equipment from surges (over-voltage spikes) on the ac power lines.
Surges may occur during thunderstorms, or because of malfunctions in the electrical distribution grid.
Surge suppressors and ac power conditioners can prevent serious damage to your on-site equipment,
including the transmitter.
RF protection
Transmitters and their antenna systems create intense radio frequency fields at the transmitter site,
particularly near the feedline, antenna and tower. At some sites, these fields may cause biological
effects, including the heating of body tissues. Intense fields can also create dangerous high voltages
on ungrounded, conductive surfaces and objects. At certain points where high voltage conductors
come close to grounded conductors (e.g., at feedline junctions or on the tower), dangerous electrical
arcing or flashovers can occur. It is very important that you take the following steps to prevent
damage to equipment or personnel due to RF fields:
• Use safety interlocks to de-energize transmitters if personnel open doors or panels accessing
high field areas
• Place warning signs in any locations where high fields can occur
• Train personnel about the short-term and long-term hazards of RF radiation
• Physically block access to the area around the antenna system, feedline and tower
• Ground all exposed conductive surfaces or objects in high field areas
The RF connection to the transmitter output can be a serious safety hazard. Connect a 50
Ω
test load
during installation and commissioning. It is recommended that a switch be used to automatically
connect the transmitter to the antenna system without human contact with the transmitting
conductors.