In the field of industrial automation, especially in high-risk environments such as textiles, assembly lines, automated warehousing, and robot workstations, protecting operators from mechanical injuries is crucial. Optoelectronic safety protection devices (often referred to as safety light curtains) have become the backbone of modern safety protection due to their non-contact and fast response characteristics. This article will delve into a classic Type2 safety light curtain system - the ULISSE UNC series, providing engineers with a detailed and actionable technical guide from system composition, installation positioning, safety distance calculation, electrical connections, to daily inspection and troubleshooting.
System Overview and Core Components
The ULISSE UNC system is not an independent safety device, but a complete safety system composed of photoelectric sensors and dedicated control units. The core design concept is that only when the photoelectric sensor is used in conjunction with a specific control unit (such as AU S3, AU S-TWIN, or AU S3M2), can it constitute a safety function that complies with the requirements of the EU Machine Directive (89/392/EEC).
1. Optoelectronic sensor (ULISSE UNC)
The system adopts a pair of photoelectric sensors, consisting of independent emitters and receivers. The shell is made of metal material and equipped with a glass lens, which makes the product exceptionally sturdy and can effectively resist the adsorption of static electricity to dust, especially suitable for complex environments such as textile factories. This sensor can reliably detect human passage, but according to its design principles and resolution, it is not suitable for situations where only arm or finger protection is required.
2. Control unit
The control unit is the "brain" of the system, responsible for evaluating receiver signals and outputting safety instructions. There are mainly three types:
AU S3: Standard control unit that can connect one or two pairs of photoelectric sensors.
AU S-TWIN: Extended control unit that can connect up to four pairs of photoelectric sensors for multi beam protection in complex areas or over longer distances.
AU S3M2: Control unit with integrated "Muting" function, suitable for specific application scenarios where materials need to pass briefly but personnel are not allowed to enter.
Key safety logic: The premise of system operation is that the protected machine must be able to be electrically controlled and immediately stop its dangerous movement at any time. If there is a risk of objects falling or splashing, additional mechanical protective devices must be installed. The system is classified as a Type 2 security system, which means that its faults or failures must be detected during the testing phase.
Essential conditions and general guidelines before installation
Before starting the installation, engineers must confirm the following conditions, which are the foundation for ensuring that the system performs its intended safety functions.
1. Environmental compatibility check
Temperature: Ensure that the temperature of the installation environment meets the specifications in the technical parameter table.
Optical interference: Avoid installing the transmitter or receiver near high-intensity or strobe light sources.
Environmental protection: The control unit should be installed in an electrical cabinet with a protection level of at least IP54.
Condensation: In places with drastic temperature differences, preventive measures must be taken (such as installing heaters or using anti condensation coatings) to prevent condensation on the surface of the lens, otherwise it will seriously affect the detection performance.
2. Mechanical and functional inspection
Machine compatibility: The hazard level of the machine must match the usage requirements of the Type2 safety system. The machining cycle or any hazardous movement of the machine must only be started by operating control components such as the start button. The safety system is only used as a stopping device and must not be used as a machine control device.
Stop performance: It is necessary to accurately know and verify the machine's stop time (t1). If necessary, actual measurements should be taken.
Test button location: The button used to activate the system testing function must be installed outside the hazardous area and the operator must be able to clearly observe the entire work area.

Core Engineering Calculation: Minimum Safe Distance (S)
This is the most critical step in the installation of the light curtain. The safe distance refers to the minimum distance between the protected area (light curtain) and the nearest dangerous point. This distance must ensure that the machine has completed all dangerous movements before anyone can reach the danger point. Its calculation usually refers to the prEN999 standard.
Basic formula:
S = K (tb + tu + t1) + C
S: Minimum safe distance (mm)
K: The speed at which the body or body part approaches the danger zone (mm/s). The usual value is 1600 mm/s.