July 7, 2017

How to Avoid Costly Emergency Repairs by Performing Proactive Maintenance in 4 Simple Steps

By Ramon Morales, NOC Operations Team, US

It’s 2:30 AM Saturday morning and the phone rings dragging you out of a deep sleep. Groggily you answer the phone and a voice at the end of the line is alerting you that the communication system is in alarm and traffic is down. While trying to figure out what’s going on, you remember you are the person responsible for your company’s communication infrastructure. Twelve hours later, the situation is finally resolved and traffic has been restored. What could have been done differently to prevent this type of situation from occurring in the first place? This is a question you will have to answer to as part of the after-action report. During incident analysis, you discovered the affected site has not had preventive maintenance (PM) performed since it was commissioned several years ago.

PM is a proactive step in ensuring critical communication infrastructure is operating within design specifications. This level of equipment maintenance will allow technicians to identify areas that require corrective actions or repairs before problems occur. Regularly scheduled PMs will help reduce the number of system outages, thus improving overall system reliability. As a general rule, PM should be performed at least once a year. A comprehensive preventive maintenance checklist can be prepared by referring to the product manual. Following is a generic scope of work guideline to assist you in creating a comprehensive PM checklist for your specific network:

1.    Site Baseline

It is always good practice to establish a system baseline to help you identify areas requiring corrective maintenance. Information that should be collected (as applicable) during a PM are:

1. Inside/outside shelter visual inspection – document the condition of the building. Check for cracks and signs of water intrusion.
2. Grounding – is there a master ground bar? Is the equipment grounded according to local grounding guidelines?
3. Transmission lines – are transmission lines grounded? What is the condition of the insulation material around the connectors? Is there a bend radius on the transmission line at the shelter entry point to prevent water ingress? Are the transmission lines supported with brackets according to installation best practices?
4. Pictures – document with photos installed equipment, cable connections, inside and outside shelter, call sign plaque, fence, tower, and any other relevant site specific information.

2.    Record Current Readings

Leveraging Excel to record readings will allow you to easily perform trend analysis to forecast possible performance degradation. While values to be recorded differ by technology, key metrics to be recorded for a microwave network include:

1. Transmit power levels (TX Power)
2. Receiver Signal Level (RSL)
3. Battery voltage readings
4. Dehydrator pressure
5. Dehydrator runtime
6. Environmental – i.e. temperature and humidity

3.    Exercise System Redundancy

(maintenance window required)

1. Switch traffic to the offline or standby modules to verify protection system is operational
2. Batteries – verify batteries are able to provide designed voltage levels under load
3. Loop protection – if using circuit loop protection, change traffic direction to validate circuit protection

4.    Upgrade, Verify, Replace

(maintenance window required)

1. Upgrade system software to match current applicable software version. Prior to upgrading software, read the software documentation to validate that the upgrade is relevant to your system. When in doubt, consult with the product manufacturer technical support.  Aviat Networks technical support can be reached at 800-227-8332.
2. Verify all cable connections are tightened to manufacturer’s specifications. Check and adjust all grounding and cable connections per the Installation Best Practices, available at www.aviatnetworks.com.
3. Replace (or clean) heating and cooling filters, dehydrator desiccant, and any other filters in use at the site.

By Ramon Morales, NOC Operations Team, US