Description

There are many Ethernet devices in use where uninterruptible operation and stable operation are crucial. Devices such as IP Network cameras for CCTV use, and Mesh style Wireless Access Points provide critical security and connectivity services respectively in many locations. In many cases these devises are supplied reliable and continuous power from some type of uninterruptible power supply (UPS). Where collocating a UPS with the critical network device is impractical, such as where providing mains power is inconvenient, uneconomical or dangerous, the use of Power over Ethernet (PoE) is usually employed, however point-source replaceable batteries (such as the Veracity Pointsource, ref. Veracity) or solar panels are alternate but not necessarily practical or economic solutions.

Power over Ethernet or PoE describes any of several standardized or ad-hoc systems which pass electrical power along with data on Ethernet cabling. This allows a single cable to provide both data connection and electrical power to Ethernet devices (ref. Wikipedia). Standardized PoE typically refers to a set of IEEE Standards that describe techniques for transmitting power over Ethernet cabling. Ad-hoc PoE refers to any other technique for achieving the same result. Collectively they are known as PoE, or Power over Ethernet.

PoE provides power to Ethernet network devices by using the same wires in the cable to carry power simultaneously with data between an Ethernet Power Supply Equipment (PSE) device, such as an Ethernet Router or Switch, and the Ethernet Powered Device (PD), such as an IP Camera or IP Wireless Access Point, however, Ethernet is capable of carrying a wider range of protocols than just IP (Internet Protocol), including NetBIOS, AppleTalk and IPX. To provide uninterruptible and stable operation the PSE is typically powered from an Uninterruptible Power Supply (UPS). This ensures that in the event of a mains power loss to the PSE, the PDs will still remain operational.

A shortcoming with the above scenario is that in the event of a breakage in the cabling between the PSE and the PDs, a loss of power is experienced at the PD. Two typical scenarios can illustrate this are where a maintenance activity damages the cable, and where a deliberate act of damage is occasioned on the cable in order to disable the device. An example of the second scenario would be an intruder attempting to damage the cabling to disable CCTV monitoring cameras. The disclosed device helps to solve these shortcomings.

The disclosed device is an Ethernet PD device that provides an uninterruptible power supply to another Ethernet device that must be protected from power loss in order to continue functioning. The disclosed device is inserted between the original PSE devise and the original PD device, and is designed to use the supplied PoE power to charge and maintain an included battery while ensuring the original PD device continues to receive adequate power. In the event of a loss of power from the original PSE device, through a scenario as described above or other fault, the disclosed device continues to supply power to the original PD device to enable it to continue functioning. Thus typically the disclosed device is located physically adjacent to the device to be protected from PSE PoE loss or failure.

The disclosed device operates in two distinct modes plus a combined mode. Mode (A) as shown in Fig.l supplies a DC (Direct Current) source of power for the protected device. Advantageously this supports Ethernet, and also non-Network connected devices that are not equipped with a natural interface for POE, but use a DC connector as their power source interface. An example of a non- Network connected device is a Wireless Camera such as the DLINK-930L (ref. D-Link); here the purpose for using the disclosed device is to provide power to the Camera without the requirement for Utility power to be located near the Camera, which in many jurisdictions globally must be installed only by a Licensed Contractor in that jurisdiction. Furthermore, the DC voltage may be offered in one single voltage level for a particular purpose (for example, 5Volts as with the DLINK- 930L), or the DC voltage may be selectable from a set of two or more discreet voltages so as to support multiple equipment (for example, many IP cameras require 12Volts DC).

Mode (B) operation, as shown in Fig.2, of the disclosed device supplies PoE power to the protected device. In this mode of operation, power is injected into the secondary Ethernet interface to be combined with the Data signals and this combined Power and Data are supplied simultaneously to the FU45 interface. In this mode, power and data are delivered to the protected device, with the disclosed device effectively transparent in operation.

Mode (C) operation, as shown in Fig.3, combines the DC power output interface of Mode (A) and the PoE output interface of Mode (B) into one device to provide a universal device for multiple-purpose deployment of the device.

To provide the Unteruptible power function, the disclosed device decouples the power from the data signal on the input interface, through a PoE splitter. A PoE splitter separates the input power and data entering the connected RJ45 interface from the PSE, and may include voltage-change cirtuit to raise or lower the incoming power voltage level to an alternative voltage suitable for the disclosed devices' internal circuitry and battery charging requirements. The input power is monitored by the input power monitoring module for the parameters (1) availability and (2) voltage level, and this information is passed to the input-display module for driving a display to indicate the input power status. Simultaneously, this information is delivered to the battery charging and discharging control module.

The separated power, when power is available from the input interface, is delivered to the battery and battery protection circuit module by way of the battery charging and discharging control module which controls the charging and discharging of the battery. If the battery is receiving more power than it is delivering, it is said to be Charging, and accumulating power.

Simultaneously, the battery is connected to the Power Voltage Regulator and Voltage-change module through the Battery Charge and Discharge control module. The Output Voltage-change module changes the voltage level from the battery to a DC level required by the output interface. Typically for a DC connected interface this will be a DC voltage up to 50Volts, or typically for an IEEE 802.3af categorised PoE injector style output the voltage will be 57Volts. The Battery Charge and Discharge module comprises circuitry to ensure correct charging and discharging of the battery, compatible with the electrochemical composition and characteristics of the said battery, which must be a rechargeable type. Preferably, said battery is Lithium Ion (LiOn) or Lithium Polymer (LiPo) type for the purpose of achieving compact sizing; however other rechargeable battery technologies will be functional, including those typically referred to as Lead Acid, Sealed Lead Acid and Gel Cell.

The Power Source Monitoring and Display Control module includes a microcontroller module; said microcontroller module function is to monitor the Battery Charge and Discharge module for Battery parameters including charging or discharging status and voltage level; said microcontroller module processing these parameters and passing data to the Display Module.

Glossary

Ethernet

Ethernet is a family of computer networking technologies for local area (LAN) and larger networks. IP Camera

An Internet protocol camera, or IP camera, is a type of digital video camera commonly employed for surveillance, and which unlike analog closed circuit television (CCTV) cameras can send and receive data via a computer network and the Internet.

Lithium Ion, Li-Ion

A lithium-ion battery (sometimes Li-ion battery or LIB) is a member of a family of rechargeable battery types in which lithium ions move from the negative electrode to the positive electrode during discharge and back when charging.

Lithium Polymer, LiPo

A lithium polymer battery, or more correctly lithium-ion polymer battery (abbreviated variously as LiPo, LIP, Li-poly and others), is a rechargeable battery of lithium-ion technology in a pouch format.

Power over Ethernet, PoE

Power over Ethernet or PoE describes any of several standardized or ad-hoc systems which pass electrical power along with data on Ethernet cabling.

PoE Injector

A PoE Injector is used to combine power and data over an outgoing network cable.

PoE Splitter

A PoE splitter is used to separate power and data coming over the network cable. Uninterruptible Power Supply , UPS

An uninterruptible power supply, also uninterruptible power source, UPS or battery/flywheel backup, is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails.

References

D-Link, nd. D-Link Products - DCS-930L. Retrieved April 2014 from

http://mydlink.dlink.com/products/DCS-930L

Veracity, nd. Portable POE Injector Battery Pack for IP Cameras. Retrieved April 2014 from http://veracityglobal.com/products/ip-camera-installation-to ols/pointsource.aspx

Wikipedia, nd. Power over Ethernet. Retrieved April 2014 from

http://en.wikipedia.org/wiki/Power_over_Ethernet