REER ULISSE UNC Security Light Curtain Practice

REER ULISSE UNC Safety Light Curtain System: A Practical Guide for Engineers from Installation to Maintenance

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.

Tb: Response time of the security system (s). For the ULISSE UNC system, the total response time (tb+tu) of the sensor+control unit is 31ms (0.031s).

T1: The total stopping time of the machine (s). Including the response time of machine control systems and drive mechanisms (such as brakes).

C: The additional distance (mm) depends on the resolution of the light curtain and/or the height configuration of the beam.

1. Single beam protection application

When risk analysis allows the use of a single beam of light to detect standing individuals entering, the beam height (H) is usually set to 750mm. At this point, the additional distance C is taken as 1200mm. The calculation formula becomes:

S = 1600 (tb + tu + t1) + 1200

Engineering Tip: When using a single beam system, it is necessary to carefully assess the risk of personnel entering hazardous areas without obstructing the beam (e.g. crawling under the beam).

2. Dual beam protection application

By vertically arranging two sets of ULISSE UNC systems, dual beam protection can be constructed. At this point, the heights (H) of the two beams of light are 400mm and 900mm, respectively. The additional distance C is taken as 850mm. The calculation formula becomes:

S = 1600 (tb + tu + t1) + 850

Calculation example:

Assuming the stopping time t1 of a machine is 0.2 seconds.

Dual beam system:

S = 1600 * (0.031 + 0.2) + 850 = 1600 * 0.231 + 850 = 369.6 + 850 = 1219.6 mm

This means that the light curtain must be installed at a distance of at least 1220mm from the danger point.

Optical installation and interference avoidance

1. Reflection surface interference

Reflective surfaces installed near the light curtain, such as walls, equipment enclosures, and smooth floors, may reflect light beams, causing the receiver to still receive the reflected signal even when the light path is actually blocked, posing a serious safety hazard.

Solution: After installation, it is necessary to carefully check whether there are such reflective surfaces around the light curtain. The testing method is to move an opaque object between and near the transmitter and receiver, while observing the green LED indicator light on the receiver, which must turn off when the light path is blocked. If the green LED remains lit during any occlusion test, the light curtain must be repositioned or the reflective surface must be treated.

2. Multi system anti-interference

When using 2 or more pairs of ULISSE UNC light curtains in the same area, it is necessary to prevent the transmitter of one system from being mistakenly received by the receiver of another system.

Installation guidelines: The transmitter and receiver must be arranged alternately (e.g. transmitter receiver transmitter receiver), and ensure that the beam of each transmitter is facing its corresponding receiver. The transmitter of one system should never face the receiver of another system.

Guidelines for Electrical Connection Practice

The correct electrical connection is the guarantee for the stable operation of the system and the realization of safety functions.

1. Power supply and grounding

Power type: The light curtain and control unit must use a PELV (Protection Extra Low Voltage) type 24Vdc ± 20% power supply. It is usually recommended to use an isolation transformer that complies with the EN 60742 standard for power supply.

Grounding strategy: The metal casing of the sensor is grounded through Pin 3 of the connector. Engineers need to pay special attention that if the sensor is installed on a machine metal component connected to the ground, the return line (0V) of the 24Vdc power supply must also be grounded. Otherwise, the metal casing of the sensor must be insulated from the metal components of the machine. This detail is key to avoiding system instability or failure caused by ground loops.

2. Wiring and anti-interference

Cable selection: For long-distance connections exceeding 50 meters, cables with a cross-sectional area of at least 1mm ² should be used.

Path isolation: The power lines, test command lines, and any related signal lines of the light curtain and control unit must be routed separately from the cables of strong noise sources such as the main power line, motor line, and frequency converter.

Control unit grounding: The control unit itself must be connected to the grounding terminal.

3. Typical Connection Scheme

According to application requirements, the document provides multiple standard wiring diagrams:

A single control unit is connected to a pair of light curtains (AU S3 or AU S3M2).

Expand the output contact capacity through external safety relays (K1, K2).

The AU S-TWIN control unit connects two or four pairs of light curtains to achieve multi area protection.

Operating principle and mandatory testing

1. Operational logic

Under normal operating conditions, the transmitter continuously emits an infrared beam. When the receiver continuously receives the light beam, its internal output is conductive (OSSD output is ON). After the control unit detects this state, its safety relay is closed and sends a "allow operation" signal to the machine. Once the beam is completely blocked, the receiver output is immediately cut off, and the control unit disconnects its safety relay in a very short time (<31ms), and the machine executes the stop command.

2. Key security mechanism: mandatory testing

According to the definition of Type2 security devices, the system must undergo regular testing to detect potential faults. The testing of the ULISSE UNC system is manually triggered through an external button. The testing process is as follows:

The operator presses the test button.

The control unit temporarily shuts down the transmitter.

The receiver should detect beam interruption and cut off its output signal.

The control unit checks whether the response time of the receiver meets the requirements and confirms that its output status changes normally.

If everything is normal, the test is successful, and the system allows for a restart.

This test must be performed every time the machine is powered on and regularly conducted during daily work.

Daily inspection, maintenance, and troubleshooting

1. Each shift/startup inspection

This is the first line of defense to ensure system reliability. The standard process is as follows:

Use a cylindrical opaque object with a diameter of 8mm.

Block the light beam at the center position between the transmitter and receiver.

Block the light beam near the transmitter and receiver respectively.

Observation result: In all the above occlusion operations, the green LED on the receiver (indicating "protection zone idle") must be immediately turned off. At the same time, the safety relay of the control unit should be disconnected to issue a stop command to the machine.

2. Maintenance

The ULISSE UNC system itself does not require special maintenance, but lens cleaning is crucial. Dust accumulation can weaken the light signal, which may cause system malfunction or failure.

Cleaning method: Regularly wipe the glass lenses of the transmitter and receiver with a soft, clean cloth.

Prohibited substances: It is strictly prohibited to use abrasives, corrosive products, solvents, or alcohol, as these substances can damage the surface of the lens.

3. Common troubleshooting process

If the system malfunctions (such as the machine failing to start or the safety light curtain not responding), please troubleshoot according to the following logic:

Step 1: Reset check. Try turning off and then turning on the system power again. Sometimes a brief power cycle can solve problems caused by transient interference.

Step 2: Check the connection. Carefully inspect all electrical connections, including control unit terminals, sensor M8 connectors, etc., to ensure that they are not loose, corroded, or disconnected.

Step 3: Check the optical alignment. Re align the optical alignment. Even slight deviations can lead to insufficient beam energy, especially on lenses with dust or slight contamination.

Step 4: Clean the lens. Clean the lenses of the transmitter and receiver.

Step 5: Final diagnosis. If all the above steps are ineffective, there may be an internal hardware malfunction. At this point, the complete system (including all sensors and control units) should be sent back to the original factory laboratory for professional testing. When sending for repair, be sure to attach detailed information such as problem description, product model, serial number, installation date, and cumulative operating time.

Summary and Selection Reference

The ULISSE UNC system, as a mature Type2 security light curtain, provides a reliable and economical personnel protection solution for many industrial environments. Engineers must strictly follow the full process specifications from safety distance calculation, environmental assessment, installation and wiring to daily testing when applying. Negligence in any aspect may lead to the loss of safety functions.

Quick selection and spare parts reference:

Complete kit (transmitter+receiver): Order code 1200302

Individual transmitter (ULISSE UNCE): Order code 1400302

Individual Receiver (ULISSE UNCR): Order Code 1500302

Common spare parts - M8 connector:

90 ° bend, 5-meter cable: 1200216

Straight head, 5-meter cable: 1200217

Straight head, 15 meter cable: 1200219

90 ° bend, 15 meter cable: 1200221