Controllis: The advantages of DC over AC generators

Controllis CEO Simon Albury has extensive experience in telecoms engineering dating back to the 1980s. Prior to setting up Controllis, Simon founded 3Way Networks, a base station company sold to Airvana in 2007. He also has experience heading up sales for ip.access, has been a telecoms analyst and strategy consultant, and deployed GSM and CDMA networks respectively for Sprint and for Bell South in New Zealand. Now Simon is turning his expertise to the challenge of reducing energy opex for operators and towercos worldwide.

TowerXchange: Where does Controllis fit in the telecoms infrastructure ecosystem?

We provide solutions to save telcos opex and maintenance costs.

Controllis manufactures DC generators and remote management systems in the UK for telecoms sites globally. Our team has extensive experience in the telecoms sector working around the world for operators, equipment vendors and on the business side of the sector. Controllis was set up five years ago to solve site power problems in particular. Since then we have developed a range of DC generators primarily focused on providing back-up power and primary power for cell sites.

TowerXchange: Our readers always want to know how proven the solution is in the field - can you tell us how many units you have installed and where they are.

We have equipment deployed in live networks in Brunei.

Controllis equipment was recently used for a huge multinational government disaster relief exercise - in a communication network linking government entities inland and ships at the shore.

In South America, we have systems deployed by a local telco in Peru, and we’ve exported equipment to Colombia, as we’re about to start a trial there with a large towerco.

In Africa, we’re coming off the back of trial deployments with a number of operators in South Africa.  We have equipment on several sites in Nigeria, and at time of writing are in process of executing large OEM order in excess of 1,000 units to Central Africa.

TowerXchange: What can you tell us about the performance of Controllis’ solutions in hybrid battery projects to date?

The fuel savings we have recorded from the hybrid system trials have been very encouraging. On one operator site the benefit compared to their existing system was greater than 70% with our average specific fuel consumption running around 0.36 l/kWh. This was with a lead acid battery bank, with a lithium bank we see an improvement of another 10% due to the very high efficiency of the lithium batteries compared to their lead acid counterparts.

TowerXchange: Tell us about the fuel efficiency and site footprint advantages of DC generators and why such considerations are critical for towercos?

DC generators have a number of technical advantages over their AC counterparts. The fuel efficiency benefits arise from a number of factors. Firstly, the alternators themselves are more efficient multipole solutions using rear earth permanent magnets - they are generating low voltage three phase current which is then internally rectified and filtered. Secondly, the alternators are mounted on the flywheel itself; this negates the need for couplings and alternator bearings and also means the units are physically shorter. Also the units do not need to run at a constant speed like AC generators, as a result of this at lower loads the units can run at lower speeds and consume less fuel.

There are a lot of wild claims on the market regarding DC generators efficiency we see a benefit in like for like operation of between 15% and 20% compared to AC generators. In a hybrid battery operation, this benefit adds to the hybrid benefit itself so the fuel savings using a DC generator in hybrid mode compared to running an AC generator in constant mode are 65% or more.

The space savings within Controllis units allow us to incorporate mains recrifiers internally within the equipment itself. This negates the need for additional cabinets for mains rectifying equipment. Saving space is critical at shared sites because it allows tower operators to provide more space to tenants.

TowerXchange: How do operators and towercos determine the optimum mix of batteries and, where appropriate, renewables, especially where the number of tenants and power requirements aren’t predictable?

This is the hundred million dollar question that every operator in the industry is facing!

Solar has become so cost effective that the incremental cost of adding panels to a site that is already configured for a battery plus generator hybrid solution is now very low. Most of the projects we are currently working on have a solar element - the only reason solar panels might not be used is because of concerns over theft and vandalism.

For me the most exciting development at the moment is from newer battery technologies. With the costs of lithium ion coming down, and molten sodium solutions emerging, the need for frequent battery bank replacements is diminishing and the total cost of ownership of hybrid systems is coming down.

TowerXchange: How are Controllis’ solutions designed to be ready to support co-locations?

For multi-tenant sites, Controllis can provide individual DC metering for each tenant. This can be remotely read and billed by the towerco, while the tenant also has local visibility of DC kWh used. The two numbers will agree, which gives more transparency to energy bills.

TowerXchange: What is the extent of Controllis’ RMS capabilities? Are we talking about integrated sensors build into your own units, or a full set of sensors, controllers and communication back to a site management system?

Both. We have built and integrated sensors into own units. We can pull in data from third party sensors and or we can monitor third party equipment such as generators, rectifiers, air conditioning units, and we can integrate data from site security.

Our site monitoring systems report back to our remote management servers via an encrypted link - the background of our RMS capability is in defence and law enforcement so it’s extremely secure. We’re now focusing on telecoms.

Our site monitoring systems are scalable to tens of thousands of deployed sites, with full redundancies.

Each of our local controllers also has full SMS capabilities to enable controllers to send alarm messages direct to service personnel at same time as communicating with the management server.

TowerXchange: What’s the typical cost per site of Controllis’ RMS solution?

Our site management solutions typically range US$2-3,000 per site, depending on quantity of sensors and number of devices monitored.

TowerXchange: What impact does remote management of power solutions have on Mean Time Between Failures (MTBF)?

Remote management has a huge positive impact on the MTBF of site power solutions. Finding issues before they become problems means preventative maintenance can avoid field failures.

A very simple example is our parameter logging; we actively log all parameters to look at trends. Perhaps the most important of these is the starter battery voltage drop on start - as soon as the starter battery starts to drop below a critical threshold during start-up it is an indicator its on the way out. Our management system sends replacement advisories out before the battery fails.

TowerXchange: Finally, how would you differentiate Controllis from other telecom power and RMS solution providers?

Our focus is almost entirely on the telecoms sector with around 90% specifically on telecoms power solutions.

We have a highly experienced team of software and electronic hardware engineers who have developed solutions that from the ground up are dedicated to the purpose of providing reliable, clean DC power.

A lot of other companies marketing DC generators have taken a parts bin approach and tried to make a range of third party devices work together, we don’t do that. A good example of this is in-sump oil level monitoring. We use the ultra reliable Perkins Engines, also made in England, and they don’t come with an oil level monitoring system as standard. So we developed an electronic dipstick in-house that enables us to retrofit a solution on the production line without needing to modify the Perkins sump.

We are also very agile being able to add in features to the software and sensors at customers requests without a lot of fuss.