Protection of surveillance cameras from environmental influences. Housings..
Protection of surveillance cameras from environmental influences. Housings.
To make the video surveillance process less dependent on weather factors, video surveillance equipment manufacturers pay attention to the fact that video camera protection does not require extra costs and the purchase of additional equipment. Thus, most outdoor surveillance equipment includes a camera housing. The functional characteristics of this means of protection are simple: it protects against moisture, dust, high and low temperatures, as well as against attacks by intruders. Camera housing– the element is quite universal and fits cameras of different manufacturers (if you purchase it separately). When installing the camera, it is necessary to take into account the weight of the camera itself plus the weight of the casing. Most casings have two-digit numbers in the model name (IP <first digit><second digit>) indicate the degree of protection in the international standard. The first digit indicates the level of protection against penetration of foreign objects (maximum protection is determined by the number 6), the second digit — the degree of protection against moisture ingress.
Camera casinghas two main types: a hermetic housing — protects the camera from dust, accidental mechanical damage, moisture and is intended for indoor installation and a thermal housing — is capable of ensuring the operation of television cameras in conditions of negative environmental influences and other aggressive environments, is intended for outdoor installation, provides complete protection from dust and protection from water jets from any direction.
Thermal housing for a camera
There are the following types: all-weather low-temperature, with a windshield wiper and washer; for use in extremely low temperatures (meet military standards for frost resistance); low-temperature — to protect thermal imagers (the viewing window of such thermal housings is made of a material that is transparent in the far IR range); to protect video surveillance systems with automatic recognition of state license plates (special light filters are used to increase the reliability of reading numbers); to protect television cameras from the effects of radioactive radiation; for use in marine climates, chemical industries and other aggressive environments (usually made of stainless steel); to protect television cameras in explosion and fire hazardous areas indoors and outdoors; cooled — to protect the camera in high temperatures; for IP cameras; vandal-proof – for additional protection of TV cameras from mechanical damage.
A few words about the most popular types:
- Outdoor thermal housingsprotect cameras installed outdoors, protecting the camera from precipitation and dust. The operating temperature range of a video camera, as a rule, varies between -10 and +40°C. At lower temperatures, which are quite possible in the conditions of the Russian winter, a thermal housing for a video camera is used. Inside such housings, heaters with a thermostat are built in, which activate their work when the temperature drops. Thermal housing for a video camera can have a fan that automatically turns on at a temperature of +30 °C. Outdoor thermal housingsare able to protect video cameras from penetration, regardless of the direction of the water flow. The heater of the thermal housing protects the video camera from fogging or icing of the lens glass, ensuring high-quality transmission of video information. Thermal housing for a video camera can also be equipped with a special washing device that can free the lens from dirt and dust.
- Anti-vandal housingis designed to equip cameras installed in places where there is a high risk of damage or destruction of the camera (at train stations, warehouses, in entrances). Anti-vandal casing is made of hard metal alloys, and bulletproof glass is used as a window for the camera. Some models are additionally equipped with a heating element that prevents fogging of the glass when using the camera in a damp or unheated room.
- Decorative casingsare installed on video cameras located indoors. Their main task is to protect equipment from dust and other airborne contaminants. Decorative housings for video cameras have a huge variety of shapes and sizes, making them easy to fit into any interior and allowing you to create a hidden surveillance system. Decorative housings are also often used as dummies of video surveillance cameras.
Choosing a thermal housing for a video camera, you should pay attention to the presence of a built-in power source for the camera. In accordance with the principles of building video surveillance systems, the camera must be charged from a stabilized source with galvanic isolation. Such a source can be built into the camera itself (for example, with a supply voltage of ~220 V) or must be located inside the thermal casing. In addition to the stabilized supply voltage for the camera, a power source with galvanic isolation ensures the absence of an electrical connection between the ground wire (or the «minus» wire of the DC power cable) and the screen of the coaxial cable for transmitting a video signal (a closed oscillatory circuit), as well as protection of the camera from damage by high-voltage impulse interference along the power line. Along the power line, video cameras are protected by a transformer of the built-in power source, and special «lightning protection» devices are used to protect the camera from the side of the video signal transmission line.