REER ULISSE UNC Security Light Curtain Practice

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.