Inefficiencies in power delivery are more glaring than ever; it's time to consider what the most efficient remote power system looks like.

When a power source is far from a power load, the system is known as a remote power system. Depending on the scale of this system, the load could be a couple feet from the source, or thousands of meters away. This article will discuss what remote power systems are, how they work, and options available to supply loads with the power they need. Unfortunately, not all these options are efficient, so we’ll also cover what the most efficient option to transmit power over long distances would be, and why. With power demands increasing, the inefficiencies in power systems are more apparent and significant than ever before, especially in larger remote power systems, making an optimal solution increasingly essential.

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Chapters: 

Why Remote Power Systems Are Increasingly Relevant

• An Increasingly Relevant Problem: Increasing Power Demands‍
• A Third Option: Class 4 Power Systems

What Are Remote Power Systems? + Different Types Of Remote Power Systems

• Large Scale Remote Power Systems
• Small Scale On-Board And Off-Board/Remote Power Systems
• Remote Vs. Integrated Drivers 

How The Ideal Remote Power System Works

Conclusion

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Why Remote Power Systems Are Increasingly Relevant

Before discussing remote power, its definition, benefits, and applications, it is necessary to understand the reason for its increasing relevance.

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An Increasingly Relevant Problem: Increasing Power Demands 

Power requirements are escalating worldwide. For example, when considering telecom, network traffic is increasing as more people and devices come online. As a result, 5G is on its way to replacing current wireless networks. However, power consumption for 5G networks is almost twice as high as that of 4G networks, so the demand for power will increase accordingly. Furthermore, network traffic is just one area where power demand is increasing.

Many of these power loads also need power supplied to them from further distances, along longer lengths of cables. Two very different examples are telecom equipment and street lights, both of which can have power fed to them from up to a few thousand meters away.

Thus, the ideal power solution to supply these additional power needs, would be able to provide higher voltages, and do so efficiently from further distances.

It’s worth noting, of course, that higher voltages intrinsically are more efficient for transmitting power along cables, than lower voltages. You can read more about this in our article about line losses, but it is evident when considering the combination of the formula for resistive power loss, and the formula for power. Voltage multiplied by current is equal to power, and so when voltage is decreased, current must be increased to provide the same level of power. Additionally, with more current, comes additional “electrical friction” which creates heat along cables, and thus more energy losses. Because of this, it’s more efficient to transmit higher voltages along power cables. 

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Currently, there are two mainstream ways to supply power remotely: 

1. Local AC Power: Local AC (alternating current) power can supply higher voltages, but using it would require the implementation of batteries for many modern applications. Why would batteries be required? Many modern power loads require DC (direct current) power, such as telecom equipment. In fact, about 74% of total electrical loads in homes need DC power to operate (if powering electric vehicles and HVAC equipment with a DC motor). Since batteries supply DC power, they are often introduced in AC systems that must supply DC power to loads, especially ones that need a UPS (uninterruptible power supply). This also means that the ideal solution to our increased power demands would not only involve higher voltages, but also be able to supply DC loads with DC power directly. 
2. Class 2 Power System: If you are familiar with the National Electrical Code (NEC) in the US, perhaps you know of the class ratings that can be applied to certain power systems that have power limitations built-in, and don’t require a fuse box or breaker panel. There are three of these power-limited class ratings (Class 1, 2 and 3). Power systems that are given the Class 2 rating, which have been recently gaining popularity, provide suitable protection from both fire and electric shock, and they usually supply DC power. This makes them relatively safe to work with, and applicable to today’s many loads that require DC power. Power over Ethernet (PoE) is an example of a Class 2 power system. The disadvantage with using a Class 2 power system is that it is power limited to 100 W per circuit, and would thus suffer significant line losses if power were to be transmitted from further distances. 

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A Third Option: Class 4 Power Systems 

There is a third option on the horizon: high-voltage DC (HVDC) power systems. A DC power system that provides higher voltages, and is considered safe from fire and electric shock, would be the ideal solution to fulfill our additional power requirements efficiently and safely. There are barriers to the development and proliferation of these systems, but recent advancements in electrical technology are breaking them down. The most recent edition of the NEC included an additional class rating in Article 726: the Class 4 rating. Class 4 rated power systems can supply up to 450V DC safely because they are fault-managed power systems. When a power system is fault-managed, it means that it has intelligence built into it so that the high voltage lines can be actively monitored for faults. When one of the predetermined faults is detected along lines, power is shut off almost immediately.

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Next, we’ll cover what a remote power system is, and how Class 4 power systems relate to them. 

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The faults that a Class 4 power system monitors for, according to the NEC, include: 

• An abnormal condition such as abnormal voltage, current, waveform, or load condition is identified in the system
• Short circuit occurs
• Human skin contact with energized parts
• Ground-fault condition exists
• Overcurrent condition exists
• Malfunction of the monitoring or control system
• Intentional shorting of the line at the receiving or transmitting end to force de-energization for purposes of maintenance or repair occurs

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What Are Remote Power Systems? + Different Types Of Remote Power Systems

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Large Scale Remote Power Systems

In a remote power system, a power supply is located separately from an electrical load. There are both large and small scale remote power systems. A large-scale example is a power transmission system. The power generator, in this case, is the remote power supply, and it’s supplying power (ultimately) to homes and buildings (remote loads).

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Small Scale On-Board And Off-Board/Remote Power Systems

A small-scale example involves charging cell phones. Cell phones are essentially circuit boards (with casings) that require power to operate. When we use our phone charging cords to power phones, we’re plugging these cords into AC outlets. Power is then converted into DC power and stepped down within the charging blocks on phone chargers, so that the proper power type (DC) and level can be delivered to our phones. This is also called an “off-board” power system because power is prepared for supply “off” the circuit board (in this case, within the charging block of phone chargers).

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When power is converted to the proper type (AC or DC), and level, within the circuitry of a load, this is considered an “on-board” power supply (or charger). An example of an on-board power system would be the process of charging an electric vehicle (EV). Sure, you plug a power supply into an EV, but an “on-board charger”, located inside the EV, converts power from AC to DC, and involves a DC-DC converter for voltage regulation. Ultimately, it’s this on-board charger that provides the EV with the power type and level it requires.   

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See below for an example of how an "on-board" charger is used when AC power is delivered to it, versus when DC power is delivered to it.

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Remote Vs. Integrated Drivers 

Another small-scale example involves how to properly power LED lighting. LED lighting is another device that requires DC power, so the local AC power delivered to it must be converted by an AC to DC converter/driver. This driver can either be remote, or integrated into the device. When drivers are integrated into an LED fixture, it’s likely that they were an afterthought for the manufacturer. In fact, integrated drivers for LED lighting can waste up to 40% of the energy consumed by a load. This makes them much less efficient than a typical remote driver, which typically have efficiencies greater than 94%. An example of an LED light with an integrated driver would be an LED lightbulb that you screw into a socket, and an example of a remote driver LED would be an LED strip that has a separate wall converter and plugs into the LED strip with a DC barrel jack.

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Aside from being more efficient, remote drivers also have other benefits: 

• Ease of maintenance: They are easier to maintain or replace because they are typically located in an accessible place such as a utility closet, cabinet, basement, or attic up to 300 ft. away from a fixture (distance is determined by the gauge of wiring used by the electrician). 
• Daisy Chain Loads: Remote drivers can regulate voltages for a string of LED loads because they are not connected to just one load (as integrated drivers are). In other words, they allow for daisy chaining, and there are a few advantages to daisy chaining. For one thing, daisy chaining makes less cable “home runs” necessary, and therefore less cabling costs necessary. Additionally, with daisy chaining, it’s easier to maximize yield efficiency. To maximize yield efficiency means to be able to use the total amount of power available in one port/channel. Daisy chaining makes this more possible because, if the yield of a port is 100 W, and you are only using 15 W loads (for example), you can string multiple loads together until no more power would be available in that channel. In this specific example, 7 loads of the same type could probably be daisy chained. 

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If you are in the market for remote drivers for LED lighting, or other DC powered devices, Cence Power provides remote power systems that can improve their efficiency. Cence LVDC is the low-voltage option (up to 100 W), and Cence HVDC is the high-voltage option (up to 450V DC, with current dependent on the voltage and power required). You can contact Cence by reaching out on their website. 

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How The Ideal Remote Power System Works

A high-voltage DC remote power system, such as a Class 4 system could work in a variety of ways (depending on the manufacturer). In this section, we’ll cover how most of these systems work, in general.

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Step 1: A Class 4 transmitter, which includes an AC to DC converter, is added to the central power system of a building. 

• The “central power system” of a building is the main source of power for a building, it distributes power from a central location, to power loads. Usually it is the AC electrical panel. In a Class 4 remote power system, a Class 4 transmitter (including an AC to DC converter, and a DC - DC converter) is connected to an AC electrical panel. A Class 4 transmitter converts AC to DC power, steps up DC voltage levels with a DC - DC converter, and sends up to 450V DC along cables.

Step 2:  Power flows through fault-managed cables, with the transmitter continuously monitoring for faults. 

• Class 4 power systems can often make use of low-voltage wiring practices, despite being able to send higher voltages. This is because they involve fault-management. When an intelligent power transmitter and receiver are on either end of a cable, they can be programmed to monitor for faults, and shut power off if one is detected.  
• This stage of a Class 4 power system is what makes it a good solution as a remote power system; it can supply high voltages of DC power, safely, along long lengths of cable before power reaches a load. Because it can supply power at higher voltages (up to 450V DC), it suffers less line losses than a low-voltage system. 

Step 3: Power arrives at a Class 4 receiver 

• The receiver receives power, and steps down voltage levels for the final length of cable before power reaches a load (this is called the “last-mile”).  

Step 4: The DC power load (such as LED lighting or telecom cell) receives power 

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Conclusion

A system like the one described above (a Class 4 power system) involves less equipment than AC systems (which might include batteries when supplying DC power), and suffers less line losses than a Class 2 power system that can only provide up to 100 W of power. When power systems are more efficient, operating costs are also reduced. So, ultimately, implementing a Class 4 power system for remote power applications could save both energy and money in the long run. If you're interested in a Class 4 power system, contact Cence Power.

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