Why might a safety light curtain or scanner fail an on-site inspection, even when its PL (Performance Level) or SIL (Safety Integrity Level) ratings meet the design
requirements?
How should a control system respond if a person passes through a safety light curtain and remains inside the hazardous area, causing the light curtain to reset?
Regarding "muting" functions on conveyor lines, what specific application conditions have changed in the latest version of the standard?
Consider an automated cell: a safety light curtain (ESPE) is installed at the entrance, with robotic arms and conveyors located inside. If a person walks through the
light curtain, the hazardous motion stops; however, once the person moves behind a piece of tooling, the light curtain resets—leaving the person hidden from view
for anyone outside the cell. Elsewhere, a "muting" function is applied to a logistics opening to allow pallets to pass through, even though the loads on these pallets
vary significantly in height and width.
This scenario illustrates a critical issue: how to prevent a hazardous restart after someone has entered the area, how to ensure no one else can enter while goods
are passing through, and whether these safety conditions have been verified following installation.
The second edition of the standard, IEC 62046:2026, focuses on the selection, positioning, configuration, and commissioning of Sensitive Protective Equipment
(SPE)—commonly referred to as ESPE (Electro-Sensitive Protective Equipment). Compared to the 2018 version, this new edition reorganizes the chapters, adds
guidance on vision-based systems, radar, and whole-body access, updates the requirements for "muting," and aligns with ISO 13855:2024. This article highlights
the changes that may impact engineering decisions.
I. Clarifying the Publication Status and the Scope of the Standard
IEC 62046:2026 was officially published in July 2026, superseding IEC 62046:2018. The European version, EN IEC 62046:2026, has also been published, and it is
currently listed as the active version by NEN.
As of November 2, 2026—the date this article was published—the standard has not yet been formally cited in the Official Journal of the European Union as a
harmonized standard under the Machinery Directive. This standard serves as a technical basis for the safety design and verification of Electro-Sensitive Protective
Equipment (ESPE)—such as safety light curtains and laser scanners—but compliance with this standard alone is not sufficient to claim a presumption of conformity
with the Machinery Directive.
For any given project, it is necessary to evaluate whether a specific ESPE technical solution is appropriate, which version of the standard is contractually required,
and whether a presumption of conformity can be established under the applicable regulations. Dates for the replacement or withdrawal of standards by national
standardization bodies cannot be directly equated to the legal transition dates published in the Official Journal of the European Union (OJEU).
It is also important to distinguish the scopes of several commonly used standards: the IEC 61496 series primarily specifies product safety requirements for the
ESPE devices themselves; IEC 62046 focuses on the application of such ESPE devices on machinery; ISO 13855 addresses the positioning and separation distances
of protective devices in relation to human body approach; and ISO 13849 and IEC 62061 are used for the design and evaluation of safety-related control systems.
Furthermore, if a specific "Type C" standard exists for a particular machine, its specialized provisions must also be verified.
The scope of IEC 62046 extends beyond just ESPE light curtains and scanners; it encompasses other types of electro-sensitive protective equipment, as well as
pressure-sensitive mats and floors as defined in ISO 13856-1.
II. Selection Process: Define Detection Requirements First, Then Verify PL and SIL
Section 4.2 of the new version consolidates various selection factors, including machine characteristics, human-machine interaction, environmental conditions,
hazard zones, human body dimensions, the suitability of the ESPE device, and its safety integrity.
These considerations are not new to the 2026 revision. They were already addressed in Chapters 4, 5.1, and 5.3 of the 2018 version. Specifically, section 5.3.2.4.2
noted that a PL (Performance Level) or SIL (Safety Integrity Level) rating alone is insufficient to determine whether an ESPE device is appropriate as a protective
measure. This principle is maintained in section 4.2.8.2.2 of the new version.
For example, an ESPE light curtain installed at an entry point must be capable of detecting the passage of an entire human body, whereas an ESPE light curtain
at an operating aperture must be capable of promptly detecting the intrusion of a finger; the requirements for detection capability differ accordingly. Although
an AOPDDR (Active Opto-electronic Protective Device, Responsive to Diffuse Reflection) may be configured with a defined protection zone, obstructions—such
as tooling, support columns, or cargo—can still create "blind spots." Furthermore, reflective surfaces near an ESPE (Active Opto-electronic Protective Device) light
curtain can compromise the reliability of detection. Factors such as ambient dust, environmental lighting, vibrations, and potential interference between multiple
ESPE units must also be evaluated against the product’s specified operating conditions.
It is also essential to determine whether the machine can effectively mitigate risks once the ESPE has triggered a detection. If the stopping performance of a
hazardous movement is uncertain, or if the act of stopping itself introduces additional hazards, the suitability of the ESPE for the intended protective task must
be re-evaluated. For risks such as ejected objects or thermal radiation, an ESPE designed for personnel detection must be supplemented by other appropriate
protective measures.
The primary updates in this section relate to the restructuring of content and the refinement of application guidance. When selecting an ESPE, one must holistically
evaluate the product certification, technical documentation, the specific objects to be detected, configuration parameters, and the risks associated with the machine.
III. Detecting Personnel Entry vs. Detecting Personnel Presence
A "trip function" refers to an ESPE's protective action: upon detecting that a person is approaching or crossing into a zone, it causes the machine to halt hazardous
movements—or reach a state where the risk is sufficiently reduced—before the person can reach a hazardous area.
A "presence sensing function" refers to an ESPE's ability to detect the continued presence of a person or a part of the human body; as long as someone (or a body
part) remains within the detection zone, the machine is maintained in a non-hazardous state. An ESPE unit may perform both functions simultaneously, provided
that its layout and configuration satisfy the requirements for both.
In the scenario mentioned at the beginning, the fact that an ESPE light curtain at an entrance detects someone "passing through" does not mean it can also detect
a person who has moved behind a piece of tooling. The restoration of the light beam at the entrance merely indicates that the specific optical path is no longer
obstructed; it cannot be used to conclude that the entire protected space is clear of personnel.
Section 4.4.2.4 of the 2018 standard already mandates that the risk of an unexpected machine start-up following entry be considered. It further stipulates that
supplementary measures must be implemented for situations where personnel might remain in areas—such as near a reset control—that are outside the field
of view. The updated versions (5.2.2.6 and 6.2.4) further refine these requirements: the reset position must provide a line of sight that allows for checking whether
anyone remains within the safeguarded space. If the line of sight is obstructed or incomplete, supplementary measures are required. The specific method chosen—
such as the use of an ESPE (Electro-Sensitive Protective Equipment) for presence detection, a sequential reset procedure, or a key-based system—should be
determined based on an assessment of the space, personnel activity, and associated risks.
For units that allow full-body entry and contain hazardous moving parts, the reset process must first disengage the interlock, followed by a separate, deliberate
start command to initiate the hazardous motion. Furthermore, if personnel are still inside, safeguards must be in place to prevent an accidental reset by another
person. While the new version (6.2.4) does allow for a reset to function simultaneously as a restart—provided that "no hazardous situation is created immediately
upon reset"—this provision cannot be applied to scenarios where personnel might still be exposed to hazardous motion within the safeguarded area.
There is also a substantive change regarding the method of machine initiation. Section 5.8 of the 2018 version stipulated that the "reinitiation of machine operation
by an AOPD" (such as a safety light curtain) was restricted to Type 4 devices; the new version (6.2.6) expands this to include both Type 3 and Type 4 AOPDs. This
application remains limited to machines involving single-operator, manual loading, and short-cycle repetitive tasks. It requires the AOPD to serve the dual purpose
of triggering protection and detecting presence, while also meeting standard requirements for start control, mode selection, and start/restart interlocks. This is a
specialized cycle-restart function; it should not be interpreted to mean that a standard safety light curtain can automatically trigger hazardous motion simply because
the detection beam is restored (i.e., the obstruction is removed).
Regarding detection response, the new section 5.2.2.7 specifically addresses whether the system can respond in time when a person walks through a vertical ESPE
detection zone. Increasing the number of scan cycles or extending the response time—often done to reduce "nuisance" (unintended) machine stops—could potentially
allow a person to pass completely through the detection zone before the ESPE system can trigger an effective response.
This is a separate consideration from the question of whether the machine itself stops quickly enough. The former requires verifying that an intrusion can be reliably
detected by the ESPE (Electro-Sensitive Protective Equipment), while the latter requires ensuring that, once detection occurs, the entire safety system can complete
risk reduction before a person reaches a hazardous location. The new version adds a specific, detailed analysis—covering both geometry and timing—to address the
first requirement; although the 2018 version did account for beam response time and human approach, it lacked this separate, more granular provision.
IV. Changes to Muting: A Focus on Personnel Access and Clearing Blockages
"Muting" refers to the automatic, temporary suspension of a specific safety function of an ESPE (Electro-Sensitive Protective Equipment) by the machine’s safety-
related control system. This is permissible only when the machine is in a non-hazardous state, or when safety is maintained through other protective measures.
The 2018 version (Section 5.7) already established requirements for automatic initiation and termination, the use of two or more independent muting signals, sequential
control, protection against tampering, and time-limited muting based on the duration required for material to pass through. The new version (Section 6.2.5) retains these
fundamental principles.
Several specific revisions, however, warrant closer examination.
First, the new Section 6.2.5.3 explicitly states that if it is easy for personnel to climb over a transport unit to enter a hazardous area, then muting is not an appropriate
application for the ESPE. Furthermore, it introduces a clear prohibition against using muting to allow industrial vehicles carrying a driver or operator to enter a hazardous
area. While previous versions already included requirements—such as ensuring the system detects the cargo rather than the pallet, and preventing personnel from riding
on pallets—the new version further clarifies these boundaries.
For instance, if the dimensions of the cargo are reduced, a gap may open up beside or above the pallet. Even if the sequence of the muting sensors remains correct, the
original condition—where the cargo itself served as a physical barrier preventing personnel from entering the protected opening—may no longer hold true. In such cases,
the entire configuration—including the cargo, the opening, the protective structure, and the ESPE/muting sensor setup—must be re-evaluated.
Second, the new version adds conditions for a specific type of "mute-dependent override" (a method used to clear blockages). Section 5.7.4.2 of the 2018 version already
permitted a time-limited override—determined via risk assessment and initiated by a momentary-action control device—provided the relevant area remains visible.
Section 6.2.5.4.2 of the 2026 version adds a further requirement: the transported cargo must cover the entire opening, ensuring that personnel cannot enter the hazardous
area by moving alongside the cargo or climbing over it.
It should be noted that this discussion concerns a specific type of time-limited override; these conditions cannot be generalized to apply to all methods of clearing
blockages. In practice, any configuration must also be verified against other requirements regarding ESPE initiation, motion control, and termination. In addition, the
new version introduces an informative Annex H, which provides guidance on estimating the SIL or PL for Muting systems. This helps in analyzing the contributions of
the Muting sensor subsystem, the ESPE control unit, and the output sections. It is based on specific assumptions and prerequisites; therefore, it should not be
interpreted as a definitive rule—such as "using two or four sensors automatically results in a specific PL"—when selecting an ESPE.
Furthermore, there are four functions related to ESPE that are often conflated in technical discussions and should be addressed separately:
・Muting: The automatic, temporary suspension of an ESPE’s safety function under specified conditions.
・Blanking: The configuration of specific areas within an ESPE’s detection zone—occupied by materials, tooling, etc.—while accounting for monitoring requirements
and the potential for personnel to enter.
・Reduced resolution: The modification of an ESPE’s effective detection capability; relevant safety distances and testing must be based on these adjusted parameters.
・Automatic detection zone switching: The selection of an ESPE’s active detection zone based on the state of the machine or the material, while ensuring that hazardous
areas remain protected at all times.
While the 2018 version (section 5.2) already addressed the safety performance of detection zones that change during operation, the new version (section 6.2.7) provides
a more detailed, structured approach. This covers aspects such as selection signals, fault response, recovery after power loss, and conditions involving material remaining
within the zone. For applications involving multiple workstations or materials of varying sizes, it is critical to verify that the switching process does not create any gaps—
unmonitored entry points—that are not covered by the ESPE.
V. Supplementary Notes on Vision-Based and Radar-Based Systems: Ensuring Compliance with ESPE Detection Criteria
The 2018 version already addressed vision-based protective equipment—including stereoscopic vision and reference-pattern-based technologies—and included an annex
on their application. Consequently, the new provisions regarding vision-based systems should not be interpreted to mean that "standard cameras can now be used directly
for ESPE safety protection."
Section 4.2.9.4 of the new version explicitly references IEC TS 61496-4-2:2022 and IEC TS 61496-4-3:2022. It mandates the verification of several factors, including coverage
area, potential obstructions, lighting and background conditions, installation angles or heights, tolerance zones, and any areas where the ESPE’s detection capability may
be limited. The new version’s informative Annex G.1.5 provides an explanation of the operating principles for radar-based protective equipment, covering aspects such as
reflection characteristics, detection zones, and motion-sensing capabilities. In engineering practice, it is essential to verify whether a specific product is capable of performing
the required ESPE (Electro-Sensitive Protective Equipment) functions—such as presence detection or triggering a protective action—including its ability to detect personnel
who remain stationary. One must not conflate the motion-detection capabilities of a standard radar sensor with evidence of its suitability for personnel safety protection.
For instance, while a 3D ESPE system might be configured to cover the entrance to a robotic workstation, the temporary placement of storage containers could alter the
line of sight or detection conditions. In such cases, the actual coverage and potential obstructions must be re-evaluated, rather than relying solely on the original ESPE
zone outlines shown in the configuration software.
This article does not detail the full type-testing requirements for these types of ESPE; product selection should always be based on the relevant product standards,
manufacturer documentation, and application-specific validation. Furthermore, the principles and examples provided in the new annex cannot serve as a substitute for
proof of suitability for a specific ESPE product.
VI. Distance, Integration, and Commissioning: Ensuring Consistency in ESPE Parameters
The updated IEC 62046 standard references ISO 13855:2024 (with a specific date). Section 5.2.2 addresses the relationship between human approach, total system
response time, safety distances (reach distances) associated with ESPE, and additional application-specific distance factors.
The changes introduced in the new version of ISO 13855 were previously discussed in the article, "EN ISO 13855:2024 Added to the List of Harmonized Standards:
What Has Changed Regarding Safety Distances for Light Curtains and Protective Devices?" It is critical to ensure that the detection capability, response time, and
detection zone parameters used in safety calculations align precisely with the configuration actually deployed on-site.
For example, if multi-scan settings are adjusted to reduce nuisance trips, or if the "reduced resolution" feature of an ESPE is enabled, the previously assumed response
time or detection capability must be re-verified. The total response chain of an ESPE also encompasses safety-related bus communication, logic processing, and the
reaction of the final switching devices (actuators); therefore, one cannot simply rely on the response time values found in the sensor’s manual. The requirement to
account for the "worst-case" response time—including safety-related communication—was already present in Section 5.2 of the previous version and is maintained
in Chapter 7 of the new version. Following the installation of an ESPE (Electro-Sensitive Protective Equipment) system, the commissioning and verification process
must, at a minimum, address the following questions: Does the actual detection zone cover all intended approach paths, and are there any obstructions or gaps that
could allow someone to bypass the protection? Does the measured overall response time align with the assumptions used during the system design phase? Is the
intended protective function maintained during entry, presence, system reset, changes in operating modes, and recovery from a power loss? Furthermore, if features
such as muting, blanking, or zone switching are employed, are the associated conditions and combined functions operating as intended?
These are not "additional tests" introduced solely in the 2026 revision. The 2018 version already mandated initial inspections, periodic inspections, functional checks,
and specific tests for ESPE applications—requirements that have been further refined in Chapter 8 of the new edition. Additionally, Chapter 9 of the new version
expands the "information for use" requirements to include specific deliverables, such as descriptions and dimensions of the ESPE detection zone, the overall response
time, and the safety integrity of individual safety functions. This ensures that field configurations can be more easily aligned with subsequent inspection and verification
activities.
For existing ESPE installations, the transition to the new standard can be evaluated by focusing on three practical areas: changes in how personnel access the area,
changes in materials or operating modes, and changes to the ESPE configuration or response parameters. By comparing these against the requirements of both the
old and new versions, you can determine what additional design documentation or verification evidence is required. This approach ensures that changes in the
standards are effectively implemented on the actual machinery.
Project Consultation
If you encounter challenges in your projects—whether related to compliance for machinery exports, ESPE risk assessments, functional safety, or safety-related retrofitting
of equipment—please feel free to reach out for a consultation.
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