A Brief Introduction of PoE and its Advantages
Power over Ethernet is an advanced technology that transmits power and data to such PoE-enabled devices as wireless access points, IP security cameras and VoIP phones via a single Ethernet cable. Installing new electrical wiring is an expensive and time-consuming process, but PoE eliminated the need for extensive wiring by reusing existing cables. With a growing demand to retrofit old infrastructures and build a fully-automated system, PoE technology will only grow in popularity for its potentials to be applied for almost any purpose.
Compared with traditional communications carriers like RS232 (point-to-point) or RS485 (multi-drop) physical layers that deliver slow, inflexible communications, PoE is a more cost-effective choice with great versatility in practical application, such as security monitoring, teleconferencing system, and access control. As a multitasking communication protocol, it’s ultra user-friendly with easy installation and maintenance (plug-and-play, no configuration). Besides, it’s an accessible technical solution where no professional support is needed. PoE only carries an electric current of fewer than 60 volts, which is relatively non-hazardous and within the skill level of the average DIYer (no licensed electricians needed for deployment).
PoE Switches Used in Harsh Industrial Environment
PoE is widely used in commercial and residential deployments, but at the same time, it is also a favored candidate in industrial settings and uncontrolled conditions because of its inherent advantages: safety (low voltage level with few possibilities of over/under-current), reliability (power source redundancy), flexibility (application to all variations of circumstances) and cost-effectiveness (uninterruptible power supply and stable data transmission-reduced costs). Among all PoE-related solutions, the benefits of PoE switches have become more evident with the expansion of IP products. Additionally, they offer greater options for networking and power supply in both commercial and industrial applications, with improved efficiency but reduced costs to build an organized and highly-function automated system.
The use of PoE switches has steadily grown in popularity in surveillance systems as the IP security cameras move toward fully integrated automation with high-energy consumption. For example, managed switches (relative to their unmanaged counterparts which do not allow for customization) open up great opportunities for authorized users to program the cameras to function in a predefined way to optimize the performance of the entire surveillance system. Users can regulate the voltage coming out of each port on the switch (only if the total power output stays within the power rating) and transmit more power to more demanding devices like Pan-Tilt-Zoom (PTZ) cameras. If the camera only requires 2-4 watts of power while the alarm needs 12-15 watts, the switch will send just enough power to each device accordingly.
What seems to be the Problem When Using Commercial Switches?
PoE switches bring a wide range of benefits to industrial settings, but not all PoE switches are created equal. Ethernet switches could be roughly classified into two categories: commercial switches and hardened/rugged switches in accordance with their applications in different settings. Compared with hardened PoE switches which require greater capital investments, as a mature PoE solution, commercial switches seem to be a fair choice for their reliability and low cost. However, in industrial realms, they are more susceptible to external interference than their hardened counterparts in unconditioned settings.
Insufficient to withstand extreme conditions: Given that commercial switches are designed in relatively controlled environments like offices, their certain specifications will not meet the standard for deployment in harsh environments, which put them at a great disadvantage in the face of ambient temperatures, excessive vibration, high-level electromagnetic interference, exposure to chemicals, etc. Additionally, commercial switches have a rather limited operating temperature range (0-40°C/30-104°F). They may possibly break down while used in places that don’t necessarily have temperature control. And fluctuations in temperature may cause overheating which is extremely dangerous in a combustible atmosphere.
People have tried many plausible ways to implement commercial switches in harsh locations, but none of them show any substantial progress. They’ve tried to connect all connections to a climate-controlled environment to protect the switch from potential hazards, but wiring could be very costly and time/labor-consuming. Another attempt to reduce wiring costs by building a climate-controlled environment also meets its Waterloo, for building an enclosure to house the commercial equipment cost more than using an industrial switch in the first place. Some may continue to use the commercial PoE switch despite the unconditioned circumstances, but chances are higher that its reliability will break down because of the mismatch.
Hardened Switches: A Better Option in Harsh Environments
Contrary to commercial switches that are designed for air-conditioned environments only, hardened switches are ideal for deployments in industrial use to withstand certain extreme conditions in harsh environments. Outside the climate-controlled environment, a hardened switch is highly needed to survive external environmental changes like extreme weather and prevent electromagnetic interference or electromagnetic susceptibility (EMI or EMS). As previously mentioned, although people can apply commercial switches to an unconditioned setting with no regard to the high costs, hardened switches can be directly installed without unnecessary, expensive re-cabling and climate-controlled enclosures.
Absolutely certified for industrial applications in harsh settings: For application in such highly demanding circumstances, hardened PoE switches will have to meet the standards of certain communication protocols like EN 50121 (electromagnetic compatibility for railway electronics), EN 50155 (electronic equipment for railway applications) or IEC 61850 (the automation of electrical substation) to ensure that they are applicable to certain scenarios like factories, railways, etc. Consequently, every component in the hardened switch is specialized with overbuilt hardware and chips to make them qualified for outdoor deployment. Moreover, the enclosure is IP-graded (Ingress Protection) using Din-rails or panels for installation.
Hardened switches are widely used in applications, such as surveillance systems, factory automation, coal mining or public transportation projects like traffic intersection monitoring. But it doesn’t necessarily mean that hardened switches have an obvious advantage over their counterparts. It all depends on a customer’s specific requirements and places where he/she plans to install the switches. In an indoor environment, say an office, commercial switches will be just enough to keep the solutions work flawlessly, so there’s no need to spend another fortune on the hardened ones. But in this scenario, the latter is clearly a better choice.
What Features do Hardened Switches have?
Considering hardened PoE switches are mostly installed in harsh environments subject to extreme temperature fluctuations, shock and vibration, etc. or applications that have higher standards like rail and intelligent transportation system (ITS) or gas and oil, thicker and heavier locking mechanisms are needed with sealed connectors and heat-resistant cables. But hardened switches have more smart features than a solid, rugged construction.
First of all, to ensure the ongoing functionality of the powered devices (PDs), the hardened switch should have dual/redundant power supplies to meet the demands of industrial uses. Powering electronic devices in harsh environments is quite challenging. They may be subject to voltage variations, power surges, lightning strikes that will cause irreversible damages to the power sourcing equipment (PSE) and PDs. Therefore, the switches must have power supply backups to start up efficiently despite all negative circumstances. Redundant power supplies (a combination of two or more power supplies for one load) are needed to lower the chances of shutdowns and failures and increase the reliability of the system, so if one power source goes down, the other will continue to provide power to the device.
To survive the significant fluctuations of temperatures, hardened switches must have a vast operating temperature ranging from 40°C/-40°F to 75°C/167°F, or their integrated circuits will overheat and under-rated connectors will shut down the connections (for both power and data) between PSE and PDs as commercial ones do. They should feature a fan-less cooling design to work in a dusty environment with a high temperature, for dust accumulation on the fan will not only slow down the operation but also disturb heat dissipation and make rattling noises. To operate in a power plant, they should have a strong resistance to vibration, noise, falls and most importantly EMI, which will cause over-voltage, under-voltage, failures in data communications between devices and burn-downs of components and circuits.
It is highly likely that they will be exposed to highly flammable gases and chemicals, so hardened switches should have an anti-explosion feature to function in a combustible and high-dust atmosphere, like oil and gas, mining, etc. So they need an IP-rated explosion-proof housing to prevent inner explosions from getting outside the container and igniting the entire area. Moreover, the switches should have other management features like power budget warning and PDs detection to ensure every device is at its optimal performance. They should be managed to enhance traffic filtering and troubleshooting so as to deliver high functionality.
What are the Differences between Hardened and Commercial Switches?
There is no essential difference between hardened switches and their commercial counterparts in terms of functionality and performance, but they do show multiple differences in other aspects because of their applications in different settings.
1.Operating Temperature Range——The specifications of hardened switches meet or exceed harsh or industrial operating environment with the ability to operate over a broad temperature ranging from -40°C/-40°F to 75°C/167°F, while commercial-grade PoE switches only have a narrow operating range of 0-40°C/30-104°F. Therefore, hardened switches are more versatile for uses in factories and industrial automation, but their counterparts are ideal for indoor environments where have a well-developed temperature control system.
2.Reliability Factors——Hardened switches are immune to nearly all negative interference like ambient temperatures, humidity and dust, vibration or shock, electrical or magnetic noise, exposure to chemicals or combustible environments. Moreover, another advantage is their longevity, for they have an extended service life of at least 10 years with a high MTBF (Mean Time Between Failure: the elapsed time between inherent failures of electronic systems) of about 300,000 hours. No maintenance or replacement is needed. On the contrary, commercial switches could only withstand air-conditioned environments with minimal humidity and vibration. And they only last for 1-2 years (MTBF: 50, 000 hours).
3.Power Supply, Operating Voltage and Installation——Commercial switches normally rely on a single power supply within a stable environment where networks are protected from power failures and only work under AC220V voltage. They are generally rack-mounted or installed on the desktops. However, hardened switches have redundant power supply backups to ensure continued operation with a wide voltage range of DC24V, DC110V and AC220V. They are normally housed in a rugged steel enclosure using Din-rails for mounting.
4.Heat Dissipation——Hardened switches use a fan-less enclosure to dissipate all the heat from the actual hardware, while the commercial ones usually are fan-distributed for cooling. On the one hand, hardened switches would not make a loud noise as their counterparts do; on the other hand, the reason why hardened switches don’t use a fan for heat dissipation is that a fan-distributed cooling system will only accelerate the progress of dust accumulation. Places like warehouses are normally dusty and dirty, so customers will have to clean the fans at least twice a year (if you get lucky). If left uncleaned, the system will break down easily.
