Скачать или смотреть Power Supply Units for Security Systems

Power Supply Units for Security Systems In general an electronic security system may be viewed as a controller and various sensors (including presence and motion sensors, smoke detectors, etc.). The controller is typically located in a heated room and has its own 12V or 24V power supply unit that may or may not have the battery-based power backup. The sensors (including video cameras, all kinds of detectors, intercoms, readers, etc.) are installed on the territory at the entrance or along the perimeters. Depending on the system, the sensors can be located either in the building, or outside. This imposes certain restrictions on selecting power supply units for various operation conditions. Power supply can be provided using various methods. Sensors are directly powered off of the network adapter at the installation location or off the main controller. In low-consumption systems (fire alarm systems) sensors can be powered using the loop. More powerful sensors require their own DC-DC converter, which converts the supply voltage of the sensor (for example, from 24 to 12 or 5V) and provides stable voltage on the power bus. For example, if video cameras are installed in a remote location, the voltage drop on the supply lines may be quite substantial, whereas the value of the supply voltage delivered to the video camera may appear to be lower than the allowable standard. If we use individual DC-DC converters with wide input voltage ranges (9-36V or 9-18V) that would be located next to the video cameras, the problem of lost supply voltage can be eliminated. Mean Well and Chinfa manufacture modules designed for building backup power supply units for security systems. These modules are protected against the discharge of the accumulator battery and against incorrect connection of the battery polarity. The devices also come with an alarm, which signals zero input voltage or zero battery charge voltage. GS series universal network adapters by Mean Well with the power of 6, 15, 18 or 15 W can be used for standalone power supply to the video cameras. These devices come with a wide input voltage range of 90-264 V AC, reliable insulation, overcurrent and short-circuit protection.