Until a few years ago, power source for CCTV cameras were limited to AC / DC power or battery power. The advent of IP cameras and advances in communication technology has opened up a variety of power options for surveillance cameras. This article describes the options available to power wired and/or wireless IP surveillance Cameras and NVRs.
There are two broad categories for the source of power:
- Power generating equipment
- Power through device connectors
1. Power generating Equipment
i.AC / DC Power
Almost all IP cameras and NVRs come with a AC/DC power adaptor to meet the device’s power requirements. A typical IP camera requires just 50 to 300mA of between 5 to 12 VDC to operate, while an NVR consumes around 3000ma @ 12VDC.
ii.Battery
For applications, where cameras need to be used in an environment where a power source is not easily available or where the quality of power is suspect, standard SMF (Sealed Maintenance-Free) lead-acid batteries or Ni-Cad (Nickel Cadmium) cells can be used. Both solutions are maintenance-free, have a long service life, high current availability, constant voltage, and the ability to be recharged. They are available in various energy options and can be used for cameras which are to be left on from 8 – 24 hours a day.The batteries will need to replaced/recharged after the completion of their power cycle; so, this solution is best for temporary or mobile surveillance requirements. The battery option can also be combined with the standard AC-power option, to deliver a power solution that drives the camera from AC-power when available and switches to the battery otherwise (like a UPS does).
iii.Solar Power
Outdoor wireless cameras are ideal for solar powered operation, especially in remote locations that are not easily accessible (for replacing/recharging batteries) or do not have an AC-power source. The PV (Photovoltaic) solar unit provides power generation by converting the energy of the sun, without the need and expense of tapping traditional power sources. The surveillance device connects to the solar unit for primary power, and is normally also connected to a battery back-up so that the device can still be used during cloudy weather, at night (if it is an infrared camera), and in the early morning/late evening when the sun is low.
2. Power Through Device Connectors
i.Powered USB
Standard USB provides a voltage source that can be used to power external peripherals.Powered USB, is an addition to the Universal Serial Bus standard that allows higher-power devices to obtain power through their USB host instead of requiring an independent power supply.Powered USB provides a single cable connection that supplies both the standard USB communication signals and two additional wire pairs for extra power. The design of PoweredUSB and it’s connectors allow for hot-plugging. This combined with Plug-and-Play operating systems allows PoweredUSB to be easily maintained and supported in the retail environmentStandard USB operates at 5 V and up to 0.5 A. This amount of current is sufficient for most PC type peripherals like mice and keyboards. When the power requirements exceed the 500mA limitation, Powered USB can be used, which provides voltage options of _5V DC, _12V DC and +24V DC at 6 A.
ii.Power over Ethernet (PoE)
PoE technology runs data and power over an Ethernet cable simultaneously. This allows greater flexibility and cost-effective installation, since cameras do not require a local power source.Today’s current standard for PoE was ratified by the IEEE in June of 2003 as IEEE Std 802.3af-2003. Since then, this standard has been incorporated into the body of the main Ethernet standard as Clause 33 during the regular revision process that created IEEE Std 802.3-2005. There are 5 classes of PoE, as per the standard and the table below lists them out.
| Class | Usage | Maximum Power Levels at Input of Powered Device [Watt] |
| 0 | Default | 0.44 – 12.94 |
| 1 | Optional | 0.44 – 3.84 |
| 2 | Optional | 3.84 – 6.49 |
| 3 | Optional | 6.49 – 12.95 |
| 4 | Reserved | (PSEs classify as Class 0) |
To transmit power via an Ethernet cable, a PoE injector or PoE capable network switch is needed. If a camera has no PoE capability built in, a PoE splitter (or PoE dongle) needs to be used. This device is connected to the camera and ‘splits’ the data from the power to deliver both in to the camera separately.The majority of fixed network cameras have built-in Power over Ethernet support. PoE is also available with pan-tilt-zoom cameras but this is less widespread as these cameras often require more power for PoE to work.
Currently, PoE is used in applications where Powered USB is inapt or where AC power would be inconvenient and expensive. However even in applications where USB or AC power is available, PoE has several advantages over either including:
- PoE cables (Even CAT 5) are cheaper as compared to USB repeaters and using PoE eliminates the task of meeting building code requirements to run AC power cable
- PoE cables also provides a Gigabit of data transfer per second to every device, which exceeds the capabilities of 2009 USB or AC power line
- PoE can be deployed easily by global organizations, without the concern for any local variance in AC power standards, outlets/plugs or reliability.
