Thus, according to structural diagram of certified security, with the help of the above sensors, firstly, by continuous monitoring of security settings. Secondly, in case of emergency situation when sensor triggered only blocked the portion of the installation, which poses a risk to humans. In this work the other mechanisms installation is not broken, and time lost to unplanned stopping the process does not occur. According to the standard EN-954-1, all elements of safety systems (safety sensor, certified safety devices and actuators) are normalized by four categories of security (B1, 2, 3, 4). Category is defined as a design engineer at the design stage of equipment at a special technique based on an assessment of the likelihood of the risks of hazardous situations.
Naturally, the category will be higher, the greater threat to personal safety is given a system or machine. For example, the control system of belt conveyor, the feed hopper into rubble, is usually responsible safety category 2. In this system, to ensure the safety of using emergency button and a protective fence. As an example, the highest category 4 may serve as a control system for waste compaction obtaining forged parts. Security personnel in this case is ensured by light curtains, located in hazardous areas, special two-handed switches that the operator uses to control installation, as well as the emergency button for emergency shutdown of equipment. Features of protective equipment to Russian enterprises in many industrial enterprises in Russia are currently in use obsolete relay-contactor control circuit arrangements, which feature is that the executive bodies of the emergency buttons, limit switches, security doors and other safety sensors connected directly (or via relays) to the coil control of electrical drives.