Srikanth Murugan, Global Director Sales Engineering, Flexenclosure
Mobile telecommunications network equipment is expected to work without issue 24/7. There is no compromise on this, which is why transmission equipment, BTS systems, RF equipment, etc., are designed, tested and built for operation in the most demanding of environmental conditions.
Click image to enlarge
eSITE from Flexenclosure
This is especially important in the developing world where the weather – particularly heat and humidity – can be extremely hazardous for highly sensitive electrical equipment. Why is it then that power systems for telecom sites are not similarly ruggedised and need to be housed in a shelter or cabinet of some kind?
The honest answer to this is that none of the power system vendors wanted to rethink the way their solutions were designed and built. It was easier to simply take componentry that was originally designed for indoor use, put it into a box and hope that it would cope reasonably well in these extreme conditions.
There are a number of significant problems with this approach though:
1. Failure at high ambient temperatures
Rectifiers and power systems are designed to work ideally at temperatures around 20 to 35 degrees centigrade. However, when the ambient temperature crosses the 45 or 50 degree mark, they start failing as they are not built for these conditions and would need special cooling solutions to keep them running. Operators need power solutions that can safely be put outdoors even in temperatures up to 55 degrees (130F).
2. Component design unfit for purpose
The first thing you always see on the face of a rectifier is the fan, which is intended to pull in cool air and release hot air. A component like this clearly cannot be exposed to the external environment as it will start sucking in dust, moisture and humidity if placed outdoors without an enclosure and a filtering system, and it will soon fail. For a reliable outdoor solution, the rectifier needs to be designed for purpose, using convection cooling rather than fans.
3. Protection needed against heavy rain
To provide reliable power to mission critical mobile networks, hybrid power systems need a minimum ingress protection rating of IP54 so they can withstand water splashing against them from any direction without any adverse effect on their operation. Essentially the power solution needs to be a completely sealed and tamper proof unit to withstand heavy rains.
4. High risk of theft
One of the main reasons power solutions are still built as indoor systems is to protect them against theft. This is because power components are typically built in modules which can easily be pulled out of the larger overall system and sold. So to avoid the risk of theft, hybrid power system design needs to be changed such that there are no removable power modules but rather just chipsets that are critical, of course, within the system, but of no value if removed.
5. Reduced lifespan of moving parts
Hybrid power systems often have moving parts like fans or mechanical automatic transfer switches. Anything that moves will ultimately wear and will need to be periodically maintained or replaced, thus incurring both cost and potentially expensive service disruption. So for a system to be built specifically for an outdoor environment, the design should ideally remove all moving parts and use only semiconductors.
Thinking out of the box
It’s clear that putting indoor power components into a box and expecting sustained performance in extreme outdoor environments is not the best approach for long-term success. So manufacturers of hybrid power systems need to think out of the box both figuratively and literally to be able to offer the market systems that are purpose-built for outdoor telecom sites and to outdoor telecom standards.
With this in mind, Flexenclosure’s eSite x10 was designed and built from the ground up to address all of the issues above and it has revolutionised the industry. It is an IP65 sealed, tamper-proof unit with no moving parts and passive convection cooling for outdoor temperatures up to 55°C. Soft switching between grid and gensets has replaced mechanical ATS’ and protects the unit from damaging input power. And specially designed power components provide additional electrical protection. This increased sophistication also allows greater amounts of power to be harvested from an unreliable grid.
The truth is there was never any logical sense in building indoor hybrid power systems for extreme outdoor use, and now there is no longer any reason to deploy them. Benefits of modern hybrid power systems include simplifiedmaintenance, longer life span, lower total cost of ownership, reduced risk of theft, simplified logistics, and improved reliability and performance. The industry is well advised to take notice.