Governments the world over are committed to keeping global temperature below 2°C above pre-industrial levels. To achieve this, greenhouse gas (GHG) emissions must halve by 2030, and drop to ‘net zero’ by 2050. Ambitious but crucial, it’s a challenge an increasing number of companies across every sector are accepting. Telecommunications is no exception. A significant contributor to GHG emissions is electrical energy consumption. SCTE estimate between 44% and 50% of cable operators’ power consumption is consumed by the outside plant. In addition to this, global warming, an increased share of EVs, and geopolitical events have had a worldwide impact on driving up prices per KWh. Price increases have materialized at a pace higher than inflation in recent years, with a growing number of countries implementing time of use (TOU) rates. As part of their commitment to minimizing environmental impacts, it became clear to Technetix that a solution was required to enable to reduce their own electricity consumption in the outside plant. Technetix’ CTO team began investigating what could be done to not only to reduce powering costs for operators, but to help them achieve their own carbon neutrality targets. The likes of amplifiers and other active devices that construct HFC architectures require power. This is typically injected into the network with a linear or ferroresonant transformer-based power supply that converts the power from the grid 100-240VACRMS to a lower voltage range of 63-89VACRMS at the same frequency of 50/60Hz. Furthermore, all active devices use solid state technology that requires DC power. Subsequently, the power received from the network must be converted to DC to be useful. This is achieved with the built-in device power supplies. Yet this power conversion process entails losses due to two main factors: 1.-Used for decades to covert high-to-low voltage, linear and ferroresonant transformers depend on the percentage of the connected load to determine efficiency. This typically increases as load gets closer to 100%. However, with the wide distribution range of loads within HFC networks, actual transformer-based power supplies operating beyond 85% efficiency are extremely rare: 80% efficiency or lower are more common. This means for every Watt consumed in the HFC network, 1.25 Watts are actually extracted from the electrical grid. For network design purposes, all components(including passives) should have a low-as-possible resistive behavior. In practice however, cables present an inductive component to their resistance levels. This is proportionate to their length, with active devices adding a capacitive behavior. These two variables contribute to the load present in the network power supply, which at this point must feed both the resistive and reactive components – inductance and capacitance – of the load. The ratio between the true power (power in the resistive load) and the apparent power (power considering both resistive and reactive loads) is defined as power factor. A power factor of 1 means the load is purely resistive and apparent power equals true power. Power factors between 0.8 and 0.9 are common in today’s networks, depending on the depth of the architecture (N+x) and the length and type of trunk cable used. Both these variables create inefficiencies in the energy transmission in HFC networks. With this in mind, Technetix investigated alternative ways of powering HFC networks. The first concept was to use direct current (DC) only. This would directly improve efficiency by supporting a power factor of 1. In addition to this, the evolution of switching mode power supplies (SMPS) since their 1970s origin has been significant, with efficiencies above 90% a reasonable expectation today.. DC-only powering was put to the test both in Technetix’ lab in an N+4 topology, and in the field in one of their European customer’s active networks. While the lab environment yielded an impressive energy saving of 26%, the field trial offered a staggering reduction of 33%. Thanks to the presence of SMPS in all active network devices, direct DC power is supported with no need for any network modifications. However, corrosion is a considerable issue with using DC-only to power HFC networks. As direct current passes through contrasting metals, usually copper and aluminum in this context, chemical reactions caused by unidirectional ion flow can corrode and damage metallic surfaces. This creates common path distortion noise issues. By examining the speed of this chemical reaction under different frequencies from DC up to 60 Hz, Technetix identified a sweet spot to optimize energy savings while minimizing corrosion. Technetix has filed multiple patents around this concept. They have also developed a smart monitoring and auto-adjust algorithm to help cable operators reduce their outside plant energy consumption by up to 30%, and get closer to attaining their carbon neutrality ...
