Pilz PSEN opII4H Safety Light Curtain Complete Guide

Pilz PSEN opII4H series safety light curtain: building a reliable defense line for industrial safety

In modern industrial production, the collaboration between humans and machines is becoming increasingly close. How to improve production efficiency while ensuring the safety of operators has become a core issue that every factory must face. As an important component of electrically sensitive protective equipment (ESPE), safety light curtains (also known as safety gratings) have become the preferred solution for industrial safety protection due to their non-contact and high response speed characteristics.

Pilz's PSEN opII4H series safety light curtains, designed as ESPE type 4 devices that comply with IEC 61496-1 and IEC 61496-2 standards, are specifically designed to protect personnel from hazardous motion injuries caused by machinery, robots, and automation systems. This article will comprehensively analyze the technical essence of PSEN opII4H safety light curtain from multiple dimensions such as product characteristics, installation specifications, functional configuration, debugging and maintenance, and advanced applications, providing a detailed technical reference for engineers and safety technicians.

1. Product Overview and Core Features

1.1 Product positioning and safety level

The PSEN opII4H series safety light curtain belongs to the ESPE type 4, which is the highest level of safety classification among safety light curtain products. Type 4 means that the device has the highest anti-interference and fault detection capabilities, and can provide reliable safety protection in the most demanding industrial environments. Its safety feature data shows that in dual channel OSSD (output signal switching device) mode, the product achieves a safety level of PL e (Cat. 4)/SIL CL 3, meeting the strictest functional safety requirements in the field of mechanical safety.

1.2 Core Technical Parameters

The PSEN opII4H series offers a total of 12 protection height options from 150mm to 1800mm, with each height corresponding to an independent order number. All models have a resolution of 30mm, suitable for hand protection scenarios. Its working distance range is 0.2 meters to 18 meters, which can cover the vast majority of industrial application scenarios. The optical system adopts an 850nm infrared wavelength, and the spacing between beams is alternately set to 15.36mm and 22.14mm according to technical requirements. This alternating design helps optimize detection accuracy.

1.3 Structural Design Features

The safety light curtain adopts an aluminum alloy shell and a die cast zinc end cover, which has excellent mechanical strength and corrosion resistance. The front panel is made of polycarbonate (PC) material, which has good transparency and impact resistance. The product has a protection level of IP65, which can effectively resist the intrusion of dust and water spray. In terms of impact resistance, the standard Swivel Mount can withstand an impact acceleration of 10g, while the Adv Bracket Kit can withstand an impact of up to 50g, making it suitable for harsh environments with high vibration and impact.

2. Installation and alignment specifications

2.1 Installation preparation and fixation

Correct installation is a prerequisite for the reliable operation of safety light curtains. The transmitter and receiver must be installed on the same horizontal plane, and their optical center axes must be parallel and aligned with each other. The connecting cable side must be located on the same side and at the same height. The installation surface should be flat, and the flatness deviation should not exceed 1.5mm.

When using the standard installation kit that comes with it for fixation, the following steps should be followed:

Clean the installation surface to ensure no dust or oil stains

Install the bracket on the end cover of the safety light curtain cable side and fix it with M3x3.4 self tapping screws with a tightening torque of 0.7Nm

Fix the bracket onto the installation surface using M6x20 cylindrical head screws with a tightening torque of 3Nm

After alignment is complete, tighten the clamping screws on the bracket with a torque of 1.1Nm

2.2 Alignment optimization methods

The alignment accuracy of the safety light curtain directly affects its detection reliability. Pilz recommends using the PSEN opII Laserpointer for auxiliary alignment. When using a laser alignment tool, the laser beam on the transmitter must be accurately directed towards the receiver, and the laser beam on the receiver must be accurately directed towards the transmitter.

If laser alignment tools are not used, manual alignment must be performed after the safety light curtain is powered on:

Rotate the transmitter and receiver, observe the protection field LED (OSSD status) indicator light on the receiver

Find the rotation angle range for the LED to change from red to green

Rotate the transmitter to the middle position of the range

Rotate the receiver to the middle position of the range

After alignment, all fastening screws must be tightened to the specified torque to ensure long-term stability during operation.

2.3 Dead zone processing

When using the standard installation kit, there will be a 15.4mm dead zone on both sides of the safety light curtain (objects cannot be detected within the dead zone). For applications that require no dead zone installation, the PSEN opII Adv Bracket Kit extension installation kit should be used. This kit provides multiple clamping units, which can be selected from 2 (150-600mm), 3 (750-1200mm), or 4 (1350-1800mm) clamping units according to the protection height, achieving installation without dead zones on both sides.

3. Calculation of safety distance

3.1 The Importance of Safe Distance

The safety distance refers to the minimum distance between the protection area of the safety light curtain and the hazard source. The setting of this distance must ensure that the operator cannot reach the dangerous area before the dangerous movement stops. The calculation of safety distance is based on the EN ISO 13855 standard, and the calculation formula is as follows:

S = K × (t₁ + t₂) + C

among which

S: Minimum safe distance (mm)

K: Approaching speed, take 1600mm/s when S>500mm, and 2000mm/s when S ≤ 500mm

T ₁: Response time of safety light curtain (s)

T ₂: Stop time of the machine (s)

C: Additional distance, set at 128mm for hand protection

3.2 Factors affecting response time

It is worth noting that when using the beam encoding function, the response time of the safety light curtain will increase. The specific values vary depending on the protection height:

300mm protection height: no coding response time 11.7ms, coding response time 15.2ms

900mm protection height: no coding response time 8.4ms, coding response time 22.3ms

1800mm protection height: no coding response time 12.3ms, coding response time 22.3ms

Therefore, when planning the safe distance, it is necessary to calculate the corresponding response time based on the actual coding mode used. Switching from no encoding mode to encoding mode is a change to the security light curtain and requires a new risk assessment.

4. Environmental adaptability and anti-interference

4.1 Distance requirements for reflective surfaces

Reflective surfaces such as metal walls and smooth floors may cause light reflection, leading to misjudgment of safety light curtains. When the reflective surface approaches the light curtain, the reflected light may bypass the obstructed object, causing the receiver to incorrectly detect the beam. Therefore, a minimum distance must be maintained between the safety light curtain and the reflective surface.

The calculation formula is: when the working distance is less than 3m, D = 0.131m； When the working distance is greater than or equal to 3m, D=working distance x tan (α). Among them, α is the opening angle of the beam, and the opening angle of PSEN opII4H is ± 2.5 °.

4.2 Interference suppression of multi light curtains installed in parallel

When two safety light curtains are installed in parallel and facing the same direction, measures must be taken to prevent mutual interference. There are two solutions:

Option 1: Maintain sufficient physical distance

For an uncoded light curtain, the minimum distance between two light curtains should be 2 × D (where D is the minimum distance from the reflective surface).

Option 2: Use beam encoding

Implement beam encoding (A encoding or B encoding) by connecting different pins. When using beam encoding, the minimum distance requirement between two light curtains can be reduced. The specific rules are:

When the distance between two light curtains is less than 2.5m, the minimum distance is 2 × D=262mm

When the distance is greater than or equal to 2.5m, there is no minimum distance limit

4.3 Environmental condition requirements

The safety light curtain should operate under the following environmental conditions:

Working temperature: -25 ° C to+60 ° C

Storage temperature: -40 ° C to+70 ° C

Relative humidity: 95% at 50 ° C (no condensation)

Maximum working altitude: 2000m (if exceeded, it needs to be reduced in capacity for use)

Avoid strong light, flickering light sources, smoke, fog or dust

5. Electrical connections and wiring

5.1 Pin allocation

PSEN opII4H uses a 5-pin M12 connector for electrical connection. The pin definitions of the transmitter and receiver are different:

Transmitter pin allocation:

Pin 1 (brown):+24 VDC (no coding or A-code); 0 VDC (B code)

Pin 2 (white): Reserved

Pin 3 (blue): 0 VDC

Pin 4 (black): Reserved

Pin 5 (gray):+24 VDC (no coding or B coding); 0 VDC (A-code)

Receiver pin allocation:

Pin 1 (brown):+24 VDC (no coding or A-code); 0 VDC (B code)

Pin 2 (white): OSSD 1

Pin 3 (blue): 0 VDC

Pin 4 (black): OSSD 2

Pin 5 (gray):+24 VDC (no coding or B coding); 0 VDC (A-code)

5.2 Wiring principles

To ensure the integrity of safety functions, the following principles should be followed when wiring:

Do not connect OSSD1 and OSSD2 in series or parallel

The power supply must use PELV/SELV power supply that complies with EN 60204-1 and has a buffering capacity of 20ms

The shell of the safety light curtain must be electrically isolated from the equipment (isolation can be achieved using the accompanying mounting bracket)

Cable bending radius: ≥ 5 times the wire diameter for fixed installation, ≥ 10 times the wire diameter for mobile installation

Maximum cable length: 50m

5.3 Auxiliary Wiring Tools

PSEN opII Y Junction M12-M12/M12 is a practical wiring adapter that can connect transmitters and receivers to one M12 port, particularly suitable for the following scenarios:

Rear channel protection application

Parallel installation of multiple sets of security light curtains

Remote control cabinet connection

6. Operation status and diagnosis

6.1 Status indication

The PSEN opII4H is equipped with LED status indicators on both the transmitter and receiver for easy on-site diagnosis

Receiver LED indication:

Green constantly on: normal operation, displaying the current reception quality (three levels)

Green flashing: Safety light curtain activated

Red constantly on: Protection field interrupted

Red/green flashing: OSSD fault or general fault

Red/green flashing alternately: stray light warning or malfunction

Transmitter LED indication:

Green constant light: normal transmission state, can display the current encoding mode (no encoding, A encoding, B encoding)

6.2 Startup and restart

PSEN opII4H adopts automatic start and automatic restart modes. When the following conditions are met, the safety light curtain automatically starts and OSSD switches to the ON state:

OSSD wiring is correct

No malfunction occurred

Protecting the field without obstruction

During operation, when the protection field is obstructed and restored to an unobstructed state, OSSD automatically switches back to the ON state, but it must meet the following conditions:

Restore the protection field to an unobstructed state

At least 80ms have passed since OSSD switched to OFF state

6.3 Fault Handling

When the safety light curtain malfunctions, OSSD remains in the OFF state. The types of faults include:

OSSD malfunction: Safety light curtain needs to be restarted

Stray light fault: can be solved by using beam encoding, installing shading plates, or swapping the position of the transmitter and receiver

Overheating fault: Check the ambient temperature to ensure compliance with technical specifications

Undervoltage fault: Check the power supply voltage

7. Advanced applications: blocking function

7.1 Overview of Shielding Function

Muting refers to the control function that temporarily and automatically suspends the safety function, allowing materials to pass through the protected area during non hazardous periods or through other safety measures. This function is widely used in scenarios such as conveyor lines and material entry and exit.

7.2 Shielded Sensor Configuration

PSEN opII4H can be used in conjunction with single beam sensors (such as PSEN op3.3) to achieve shielding function. The minimum distance must be maintained between the shielded sensor and the safety light curtain to avoid mutual interference. The working wavelength of the shielded sensor must be different from the safety light curtain or maintain sufficient physical distance.

7.3 Blocking Application Types

Cross Muting: Suitable for materials entering and exiting hazardous areas. Two shielded sensors are arranged in an intersecting manner, with their intersection point located behind the protection field. The triggering time interval between the first and second shielded sensors shall not exceed 4 seconds.

L-type shielding: only applicable for materials leaving hazardous areas. The following distance requirements must be followed:

Shielding sensor 1 and 2 spacing>100mm

Shielding sensor 2 and protection field distance>100mm

The length of the object triggering the shielding state is greater than (a+b)

The distance between two transported objects is greater than (a+b)

T-shaped shielding (sequential shielding): suitable for bidirectional entry and exit of materials in hazardous areas. Four shielded sensors are required, arranged in a T-shaped pattern. Recommended distance requirements in accordance with IEC 62046 standard.

7.4 Unauthorized Functions

When the blocking function fails, the override function allows manual operation to clear the fault. Unauthorized operations must meet the following conditions:

Unauthorized activation is only allowed when at least one shielded sensor has been triggered and the protection field is obstructed

Unauthorized activation will not automatically initiate movement and requires separate control of the device

If the hazardous area is not visible, a spring reset key switch must be used and an emergency stop must be initiated from the same position

8. Regular inspection and maintenance

8.1 Daily Inspection

Pilz recommends regular check ups every six months:

Check the front panel: replace if scratched, clean if dirty

Check fasteners: All screws must be tightened to the specified torque

Check safety function: Use a test stick to block the protection field at different positions and verify whether OSSD switches normally

8.2 Cleaning and Maintenance

The cleaning of the front panel of the safety light curtain only requires the use of a damp cotton cloth, and the use of alcohol, solvents, wool cloth, or synthetic fiber cloth is strictly prohibited to avoid damaging the surface. In environments with high levels of dust, the frequency of cleaning should be increased.

8.3 Inspection after renovation

After each of the following modifications, safety checks and risk assessments must be conducted again:

Replace the safety light curtain or its components

Change the wiring method (such as changing from no coding to coding mode)

Change mechanical structure or safety distance

9. Summary of Technical Parameters

9.1 Electrical Parameters

Supply voltage: 24 VDC, tolerance -25%/+20%

Residual ripple: 5%

Maximum power consumption (OSSD OFF): 2.5W

OSSD switch current: 100mA/channel

OSSD voltage drop: 1.5V

Maximum test pulse width: 300 μ s

9.2 Environmental and mechanical parameters

Protection level: IP65

Vibration resistance: 10-150Hz, 0.75mm amplitude, 0.2g acceleration

Impact resistance: Standard bracket 10g/16ms, expansion bracket 50g/11ms

Material: The shell is made of aluminum alloy, and the end cap is made of die cast zinc

Weight: 150mm protection height 1.82kg, 1800mm protection height 5.06kg