Power-over-Ethernet and fibre optics – Luke Frost examines the latest power solutions to save installation and running costs on the mine site.
As a transmission medium, fibre-optic cable provides plenty of benefits that can’t be matched by traditional copper wire, or AC power. Signal clarity, greater installation range and no electromagnetic interference (EMI) makes it an ideal choice for a large scale outdoor application like an open cut mine. A Power-over-Ethernet (PoE) network can also run surveillance cameras, wireless access points, industrial sensors or VoIP communications systems.
“Power-over-fibre is a rapidly developing technology, converting a signal from electrical-to-optical- to-electrical.”
Power-over-Ethernet allows a relatively low-powered device to operate on the same Cat.5 Ethernet cable that supplies data flow, effectively halving the amount of cable that an installation will need. Typically a large-scale deployment of security cameras would take a data cable for transmitting digital images (or analogue cable for closed-circuit TV cameras) as well as copper cabling for the power supply. Since cameras and wireless access points tend to sit on a ceiling or in a high position to generate the best view or reception, it usually involves running cable to each individual device, often in hard-to-access positions. PoE allows the devices to run on just the one cable, supplying both power and data to the networked devices. This means that a separate power supply next to each device is no longer needed.
PoE has been around for a number of years – early IP phones used the technology well before it was broadly recognised as an alternative means of delivering power to a device. Two methods of achieving PoE have subsequently been standardised by the Institute of Electrical and Electronics Engineers (IEEE). PoE provides up to 15.4 Watts of power, while PoE+ can accommodate up to 25.5 Watts. Formally approved as an international standard, PoE is established as an economical, safe power distribution method and is already deployed in corporations throughout the world.
From the outset, PoE saves a company money. An installation that runs PoE devices will require half the hard wire, and significantly reduces the installation time. Fewer electricians, less drilling, smaller conduits. Ethernet cables are relatively cheap, offer a fast data rate and allow Peer-to- Peer (P2P) networking among linked devices. It also negates the need for environmentally harmful batteries in areas that lack a traditional AC power supply.
Power-over-Ethernet also provides a means of better managing power consumption, as PoE devices are often scalable – that is, they can be turned up or down on demand, using built-in power management features. Power Sourcing Equipment (PSE), such as a PoE network switch, looks for a device on the Ethernet cable that requires power, and sends the required amount to the device. Think of the managed PoE switch as allocating a ‘budget’ of power to each device – similar to how the cloud maximises server resource potential, a managed PoE switch optimises electricity usage. Managed PoE switches can also be set to turn off a device when idle, resulting in big power savings over time. Standby power can be as much as ten per cent of a company’s total consumption, so being able to control a device’s power ‘draw’ when not in use can have a dramatic effect on overheads.
In contrast, a standard electrical converter requires constant AC power, provided by copper wires, cannot be easily managed to optimise power, and will be susceptible to power surges and blackouts.
Standards such as IEEE 802.3az EEE (Energy- Efficient Ethernet) require a PoE device to comply with environmentally-beneficial guidelines. Most modern PoE devices on the market will conform to them, which ensures that power management technology is built in to provide optimal power usage and auto on/off functionality.
Typically, PoE has been limited by the range and power that Cat.5 cables can supply, best operating with low-powered devices. However, products now exist that can transmit data and power over a fibre-optic cable, which increases the size of a network exponentially – in some cases up to two kilometres from the original power source. Power-over-Fibre (PoF) has emerged as a very viable means of creating a long-range connection between a device and a power/data supply, with PoE products that utilise the new fibre technology now becoming available.
Power-over-fibre is a rapidly developing technology, converting a signal from electrical-to- optical-to-electrical. As such, it provides electrical isolation between the device and the power supply. This creates another clear benefit to the mining industry, since a PoF system helps protect the power supply and devices from dangerous voltages such as lightning strikes, and can also reduce the risk of voltage from the supply igniting explosives.
Innovative long-distance PoE solutions using Power/Fibre Hybrid Cable (PFHC) technology will be of particular use for large-scale outdoor surveillance installations such as those found in Australia’s resources sector. A PFHC transmitter transfers power long distances via optical fibre cabling, which then attaches directly to a PoE device at the point of installation. Again, this saves a corporation the need to build weatherproof enclosures to house PoE repeaters and power switches, which previously had to be installed approximately every 100m along a network to maintain power.
A typical Power/Fibre Hybrid Cable surveillance installation might deploy as follows: a simple, non-PoE switch at the power source connects directly to a chassis holding four receivers. Each receiver might have four ports, allowing connection for up to four powered devices (PDs). For an extended surveillance installation, this enables four PoE surveillance cameras to be connected to each receiver, and eight receivers each connected to its own transmitter at the central chassis, making a network of 32 cameras possible per chassis. With Power/Fibre Hybrid Cable supporting a range of up to 2km from the chassis, cameras can be spread out over a 2km radius.
For a large installation such as those found on a typical mine-site, fibre is the clear winner over traditional copper-based PoE installations when it comes to large-scale networks, based purely on the range that it offers. Data transfer is also superior using fibre, and is a factor worth considering when planning new sites or network upgrades. Using a digital signage installation as an example, it is possible to send an HDMI signal over 40km by daisychaining receivers, and since fibre has very low dispersion, there will be almost no drop-off in image quality. Copper generally offers a range of about 250m before image quality is affected, with the signal deteriorating at each link in the chain. With a fibre backbone, it is easy to run PoE devices at selected points along the network, increasing the flexibility of future operations.
A long-range digital signage installation over fibre-optic extenders requires just four items: an image source such as a DVD player or PC at one end, connected to a transmitter which sends the audio and video over fibre optic cable to a receiver, which plugs into the monitor at the display end. This is the most effective and cost-efficient way of setting up an installation for large-scale facilities that require signage a long distance from the source.
Just another point of consideration – fibre works best as a point-to-point solution, carrying a signal quickly and efficiently over long distances. In some circumstances it is not so good at distributing that signal to multiple monitors at the display end. Fibre is best suited to situations where one server sends a signal to multiple display units over a long distance.
So fibre tends to be the best choice for large-scale deployments with few screens, and either an IP or hybrid setup works best for large-scale deployments with multiple screens. The hybrid solution can offer the speed of fibre over a long distance, then split the signal using copper at the display end, making it a good way of setting up a traffic-heavy end-point that needs lots of displays over a wide area.
PoE surveillance cameras are fast taking off, as once again they negate the need for an alternate power source near each device in the network. More PoE surveillance devices have emerged on the market recently, with much greater choice available. Many suit the tough outdoor conditions inherent in Australia’s mining industry, with high IP ratings to keep out heat and humidity, rain, dust and vibrations. Industrial-standard PoE extenders, repeaters and switches are also available, which again saves a corporation installation costs by negating the need for a weatherproof switching box or housing for a separate power supply.
With fewer wires, a PoE network also reduces the risk of failure or accidental shut-off, which increases business continuity and helps when assessing potential problem areas during risk audits. Adding an uninterrupted power supply (UPS) to the network guarantees power availability, even in the event of a power failure at the source.
Safety is paramount on mine sites of course, and PoE as an energy source can reduce some significant risk factors. As discussed previously, optic fibre isolates the power between a switch and the device, reducing the risk of a threat such as a lighting strike. PoE further reduces the risks associated with having high voltage lying close to the surface of the ground, since the maximum current in a PoE system is 48v of DC power.
PoE as a power source also helps in protecting the investment of surveillance cameras and communications equipment, since it eliminates the pathway for a power surge to knock out equipment. With many smaller mine sites operating in remote locations around Australia where finding a reliable power supply remains a critical issue, PoE running to surveillance and communications equipment reduces one layer of risk from surges and power spikes.
Flexibility is another area that PoE offers plenty of benefit to an Australian mine site. Since a device running on PoE has no need of an independent power supply, cameras and wireless access points (WAPs) can be mounted in positions that are the most suitable to the end-user, rather than positions where a power switch can be easily deployed or is already located. Wireless access points are most commonly mounted on the ceiling or at least in a high place, so almost always need to have a power switch specially installed next to the device. A PoE access point negates the need, running on the same Cat.5 Ethernet cable that is already supplying the data flow
The same flexibility applies in situations where a network is to be extended. If a site expands and the network needs to expand with it, installation costs and times associated with a PoE system are effectively halved, and a network can be planned and deployed in the most effective format, rather than one that is compromised by cost and access restraints. Better flexibility when planning a network of devices leads to more efficient network designs and optimises the equipment to be deployed. Network modifications will have less impact on the successful running of an operation, with fewer delays increasing business uptime.
Remote management of devices is also a crucial benefit to any PoE network. Devices can be monitored from a central location, and controlled easily by a central management software program. This allows an administrator to see if there is a problem within the network, remotely shutting down any problem areas. Power supply to each device can also be controlled from the central point, so an administrator can quickly and easily turn power down to conserve energy in cases where a device does not need to be operational for some reason. This saves the time and expense of sending a technician or an electrician out to each device that needs to be reset or shut down, again saving the organisation significant overheads.
This also lends itself to increased security, since an access point can be powered down if there is no activity in the area for any length of time, rather than maintain a wireless network in a redundant space.
Remote management also impacts on the physical administration and monitoring of a security network, as many elements of a security plan can now be converged into a single pane-of- glass, or at least consolidated in the one central space. Cameras, access control systems, alarms and even fire safety equipment can be controlled from a central point, so the ability to also monitor and action power consumption in each individual device in a security network increases that level of control.
In conclusion, Power-over-Ethernet has a lot of benefits to Australian mining, especially taking into account the scale of our operations and the diverse environmental conditions that our operations face. PoE can reduce risks associated with wear-and-tear, lightning strikes and power surges; it saves significant running costs by scaling the amount of power each device draws; installation costs are reduced as well as the time taken to deploy or extend a network; security is enhanced, it ticks environmental boxes since power draw is reduced, and flexible design leads to more efficient running of devices. Especially since fibre has been introduced, PoE and PoF are very viable alternatives to running a security or communications network on standard AC power.
“Power supply to each device can also be controlled from the central point, so an administrator can quickly and easily turn power down to conserve energy in cases where a device does not need to be operational for some reason.”
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