Equipment installation and maintenance
A telecommunications site has to work all the time. That does not depend on the radio equipment but on everything around it: the power supply, the ground, the temperature, the record of what was done and the discipline with which it is worked on.
Radio-frequency instruments and measurements on transmitters and receivers are covered in measurements and installation in RF, and the general framework for prevention in health and safety. Here we work on the complete site and its maintenance over time.
01The site
| Element | What has to be solved |
|---|---|
| Power | Rectifiers that deliver −48 V DC and keep the battery bank on float charge. It is the classic telecommunications scheme, and the reason a site keeps working during an outage. |
| Backup | Battery autonomy sized in hours, and a generator set with automatic start at critical sites. Autonomy is tested, not assumed. |
| Grounding | A single grounding grid to which the structure, cabinets, surge protectors and shields are connected. Everything at the same potential: this is what keeps a discharge from flowing through the equipment. |
| Lightning protection | Lightning rod, down conductor, and surge protectors on every line entering the building: coax, power and data. |
| Climate | Air conditioning with temperature and humidity control. Electronics running hot age much faster. |
| Access and security | Fencing, access control, entry log, lighting, and intrusion and fire detection. |
| Tower | Structure, guy wires, aviation obstruction lighting, ladder with fall-arrest line and cable support. With periodic structural inspection. |
The costliest mistake at a radio site is having separate grounds: one for the lightning rod, another for the equipment, another for the power. During a discharge, each one sits at a different potential for microseconds, and the difference discharges through the equipment, which is the only thing that connects them.
The rule is a single grid, with everything bonded together: structure, cabinets, shields, surge protectors and neutral. Bonding everything may seem counterintuitive, but it is precisely what guarantees there is no potential difference.
02The maintenance plan
| Frequency | Tasks |
|---|---|
| Monthly | Remote review of alarms and levels, temperature check, verification that there are no “normalized” alarms that were acknowledged without being resolved. |
| Quarterly | Site visit: cleaning filters, visual inspection of connectors and seals, checking the obstruction lights and the emergency lighting. |
| Semiannual | Power and VSWR measurement, thermography of panels and rectifiers, test of switchover to backup, check of the battery float voltage. |
| Annual | Real battery autonomy test with a controlled discharge, grounding measurement, structural inspection of the tower and guy wires, retightening of terminals, generator set check under load. |
| Per event | After every major electrical storm: inspection of the surge protectors, which are sacrificial elements and may have operated. |
- VSWR of the radiating system: its trend over time reveals water in the coax or a connector that is degrading, long before the link fails.
- Received link level: logged daily, it shows whether the margin is being eaten away by vegetation, antenna misalignment or equipment degradation.
- Error rate: it gets worse before the link goes down.
- Internal temperature and operating hours of the air conditioner.
- Internal impedance of the batteries: it grows with aging and anticipates the loss of autonomy. It is a much better indicator than voltage.
A battery bank on float measures its nominal voltage even if it has lost almost all its capacity. Everything seems correct until the power outage, when the site shuts down in five minutes instead of lasting eight hours. That is why autonomy is tested with a real discharge at least once a year, and the internal impedance of each cell is measured.
03How to work on a site
- Give notice: a site provides service to someone. Every intervention is coordinated and announced beforehand.
- Back up the configuration of each device before changing it.
- Have the rollback plan: how to return to the previous state if something goes wrong, and in how much time.
- Bring the necessary spare parts and tools. A site is usually far away.
- Schedule the work window at the time of lowest traffic, not the most convenient one.
- Never alone at a remote site or on the tower. And with communication verified before climbing.
- Work at height with a full-body harness, double lanyard and lifeline. Never in a storm, strong wind or wet conditions.
- Ask for the transmitters to be switched off before working in front of active antennas, and confirm it with the operator, do not assume it.
- Battery banks deliver enormous short-circuit currents: insulated tools, no rings or watches, and face protection.
- Electrostatic discharge when handling cards: wrist strap and dissipative surface.
- Suitable fire extinguisher and a clear exit. In a room with extinguishing gas, learn the evacuation procedure before entering.
Room plan with the location of each rack, single-line diagram of the power supply, list of equipment with serial number and firmware version, network address table, diagram of the radiating system with lengths and connectors, log of interventions and emergency contacts. All of that lives at the site and also away from it.
It serves the same purpose as always: so that whoever goes out at three in the morning to fix a fault does not have to reconstruct the installation from scratch.
04In the lab
On a real installation —the school’s system, a local radio station, a wireless internet node— survey all the elements, draw the power and ground diagram, and put together the equipment spreadsheet. List the nonconformities found.
With a battery and a known load, measure the real capacity by controlled discharge and compare it with the nominal one. Also measure its internal impedance. Repeat with an old battery: the difference in resting voltage is usually minimal and the difference in capacity, enormous.
Measure the resistance of the site’s grounding and verify continuity between the structure, cabinets and surge protectors. Look for loose or painted joints, which are the most common and the most invisible defect.
Write the complete plan for a site: tasks, frequency, instruments, acceptance criteria and log sheet. Carry out a real quarterly round and document it the way it would be delivered to a client.
05Common mistakes
| Mistake | Consequence |
|---|---|
| Separate grounds for the lightning rod and the equipment | During a discharge, the potential difference discharges through the equipment. |
| Assuming battery autonomy | At the first real outage the site shuts down within minutes. |
| Not inspecting the surge protectors after a storm | They are sacrificial elements: they may have operated and no longer be able to protect. |
| Air conditioning without maintenance | The temperature rises, the electronics age quickly and failures multiply. |
| Alarms acknowledged and never resolved | The system stops warning about what matters because nobody looks at the alarms anymore. |
| Working without a configuration backup | If something goes wrong there is no way back. |
| Working alone on the tower | In the event of any accident there is nobody who can raise the alarm or assist. |
| No documentation at the site | Every night-time fault starts with reconstructing the installation from scratch. |
06Self-assessment
Why do telecommunications sites run on −48 V DC?
Because it allows the equipment to be powered directly from a battery bank on float: during an outage, the site keeps working without any switchover.
Why must the grounding be single?
Because with separate grounds, during a discharge each one sits at a different potential and the difference discharges through the equipment, which is the only thing that connects them.
How is the autonomy of a battery bank verified?
With a real discharge test and by measuring the internal impedance of each cell. The float voltage says nothing about the remaining capacity.
What is inspected after an electrical storm?
The surge protectors on all the lines entering the building: they are sacrificial elements and may have operated, leaving them unable to protect the next time.
Which indicator anticipates a failure of the radiating system?
The VSWR trend over time: it reveals water in the coax or a connector degrading long before the link fails.
Why does the room temperature matter?
Because electronics running hot age much faster: service life drops sharply with every sustained increase in temperature.
What must be settled before changing a device’s configuration?
The backup of the previous configuration and a rollback plan: how to return to the previous state and in how much time.
What special precaution does a battery bank require?
It delivers enormous short-circuit currents: insulated tools, no rings or watches, and face protection.
What problem do acknowledged but unresolved alarms cause?
Staff stop looking at them, and when one that does matter appears it goes unnoticed among the usual ones.
What documentation must be available at the site?
Room plan, power and ground diagram, list of equipment with serial number and firmware, address table, radiating system diagram, log of interventions and emergency contacts. And a copy kept away from the site.