| 摘要 |
Safety device intended to convert an optical signal passing through a sensor for optical fibres (external to the system) into an electrical signal controlling two electromagnetic relays whose contacts, placed in series, can be used in the automation of the machine or item of equipment to which some access is to be controlled (protective panels, casings, etc.). It is in the form of a small box (1) intended to be placed in an industrial electrical cabinet. The electronics of the mounting plate (13) associated with the emitting diode (2) provides (and, in return, receives) frequency-modulated red light which will be conveyed as far as the abovementioned sensor with the aid of two optical fibres (4) and (5). The return signal (when the sensor is closed) is compared with that emitted. The output relays are activated when the results coincide. These relays, just like the power supply for the box (1) are supported by the mounting plate (12). The device is equipped with a system which checks that the two output relays both have their contacts closed simultaneously. The diode (2) and the phototransistor (3) (which receives the return signal) will be located in special supports (6) on which automatic connectors (7) taking the fibres (4) and (5) will be placed. By virtue of its two essential functions: coincidence of the emitted and received signals, and control of the contacts of the output relays (relays with guided contacts), this device aims to obtain homologation in terms of matters of security. <IMAGE> |
