Application: The safety switches with separate actuators are suitable for sliding, hinged and especially for removable safety guards, which need to be closed to ensure the necessary operational security. They can also be fitted on profile sections and retrofitted on existing equipment.
All class 2 safety switches shown in this chapter will attain category 3 or 4 to ISO 13849-1 in combination with a guard door monitor.
Design and mode of operation: On the class 2 safety switches, the switching element is not physically connected to the actuator but functionally brought together or separated when switching. When the safety device is opened, the actuator is separated from the base device. During this process, the NC contacts in the safety switch are positively opened and the NO contacts closed.
Enclosure rating of all the safety switches is IP 67. The safety switches can be fitted in any desired mounting position.
Application: The solenoid interlocks of the AZM series have been designed to prevent, in conjunction with the control part of a machine, e.g. fail-safe delay timers or fail-safe standstill monitors, sliding, hinged and removable safety guards such as fences, flaps or doors, from being opened before hazardous conditions (e.g. run-on movements) have been eliminated.
These solenoid interlocks are also used for cases in which the opening of a guarding device represents a non-permissible intrusion in a production process.
Design and mode of operation: On the AZM range solenoid interlocks, the switching element with interlock is not physically connected to the actuator but functionally brought together or separated on switching. When the safety guard is opened in the unlocked condition, the actuator is separated from the base unit. During this process, the NC contacts are positively opened and the NO contacts closed.
Interlocking is carried out by means of a blocking bolt / latching bolt. This latching bolt blocks the actuator so that it cannot be withdrawn from the interlock. The machine control is only enabled when the actuator has been inserted into the interlock and the latching bolt is in blocking position. This is ensured by the contact monitoring of the latching bolt.
There are two modes of interlocking. The "Power to unlock" principle is where the locking bolt is held into position with a spring. When the de-interlocking coil is energised, the interlock is removed and the NC contacts opened. The protection equipment can be opened. For "Power to lock"1) the mode of operation is reversed.
The solenoid interlocks AZM 161, 170, 190 and 415 are fitted with protection against incorrect locking. Depending on the type of unit, an individual coding of the actuator are possible.
The solenoid interlocks can be fitted in any desired mounting position. Protection class of the solenoid interlocks is IP 54, IP 65 or IP 67.
1) In accordance with the policy of the German Technical Assessors, these interlock may only be used after a thorough evaluation of the accident risk, since the guarding device can immediately be opened on failure of the electrical power supply.
Application: The safety switches are suitable for hinged safety guards, which need to be closed to ensure the necessary operational safety.
A comprehensive range of safety switches for rotating guard systems is available to meet the most diverse requirements in actual practice.
Depending on the device configuration and design, both small doors and service flaps as well as heavy hinged guards can be mounting- and maintenance-friendly secured in machinery and plant building.
Design and mode of operation: An advantage of the safety switch shown here is integration of the cam into the switch. The requirements of EN 1088, such as positive linkage between cam and actuator as well as protection against tampering are thus fulfilled.
This combination within the switch provides cost advantage for the user in avoiding the necessity of mounting a specially designed cam.
These safety switches are mounted with slow action.
Application: The magnetic safety sensors are used to monitor the position of sliding, hinged or removable safety guards. Sensors without integral evaluation can only be used for safety duties to IEC 60947-5-3 in combination with a safety guard monitor for protection up to Control Category 4 to ISO 13849-1.
The use of magnetic safety sensors is of particular advantage in cases where extremely dirty conditions can occur or high hygienic standards need to be maintained. This is provided by the simplicity of cleaning of the devices.
Another advantage is the possibility of concealed mounting behind non-magnetic materials. Working surfaces and storage areas can be arranged without the need for dust-collecting edges or other functionally required cut-outs or projections.
In applications, where a precise approach is not possible and larger tolerances are required, the magnetic safety sensors of the BNS series can also be used.
Design and mode of operation: These devices comprise a multi-channel magnetic safety sensors and an actuating magnet.
All magnetic safety sensors are in thermoplastic enclosures and protected to protection class IP 67 or 65.
Application: Pull-wire Emergency Stop switches are mounted on machines and sections of plants which cannot be protected by guards. The advantage of pull-wire switches over mushroom head Emergency-Stop push buttons is that the Emergency-Stop command can be triggered anywhere along the wire.
In combination with one of the AES and AZR range safety monitoring modules pull-wire Emergency Stop switches can be used for Control Category 3 or 4 to ISO 13849-1.
Design and mode of operation: All of the pull-wire emergency stop switches meet the European Standard EN ISO 13850. They have a positive linkage between the NC contacts and the wire rope. The pull-wire emergency stop switches are brought into the operational condition by pre-tensioning the wire, i.e. the NC contacts are then closed and the NO contacts open.
All of the pull-wire emergency stop switches have wire-breakage monitoring. On pulling or breakage of the wire, the NC contacts are positively opened and the NO contacts are closed. The pull-wire Emergency Stop switch can then only be returned to the operational condition by a resetting operation.
Application: Command and signalling devices are of great importance for the man-machine interface in the field of industrial applications. They are used, for instance, in control cabinets, control panels, two-hand control panels, in elevator construction or on conveyor and material handling plants. The manual actuation of the devices starts or stops operating sequences and functional processes
Design and mode of operation: Command devices are available in the form of pushbuttons, joystick switches or key-operated switches. The actuators are connected to the switching element through a bayonet socket.
Standard in higher – quality instead of “do-it-yourself” The basis of the BDF series is a slim enclosure in shock-resistant plastic, which can be quickly and smoothly fitted on the customary aluminium profile systems used in mechanical engineering and which can accommodate four control elements. As the control elements are regarded, the user can choose from a comprehensive range of illuminated pushbuttons, selector switches, signalling devices with LED, key-operated switches and standard-compliant emergency stop command devices.
Adjustable to the user’s needs All control elements have the same contacts. In this way, the user can choose their position on the control panel depending on the individual requirements. Also as the labelling is regarded, the BDF control panels can be adjusted to the individual needs. To this effect, labelling areas with plastic cover are provided, in which two-layer plastic identification labels can be applied. In the course of the development, the Schmersal engineers have interviewed many customers about the desired features and functions, which such control panel should include. The results of these surveys have been integrated in the design of the BDF series.
Application: Optoelectronic safety device are used as entry, danger point or danger zone guards
The new safety light barriers of the SLB 240 and SLB 440 series are very compact and feature integrated evaluation. The product family is designed as type 2 (PL c) and as type 4 (PL e) and can be directly integrated into the safety circuit.
Design and mode of operation: The SLB versions offer a 4-stage coding. This means that up to 4 sensor pairs can be used in an application in one direction without reciprocal influence. The modes of operation available are setup, automatic or restart and also diagnosis.
The SLB 440-H version can be used in outside areas with an integrated heater for very low temperatures and monitors eight access areas up to a distance of 75 m.
Application: Optoelectronic safety devices are used to protect access to hazardous points or hazardous areas.
>SLG/SLC range safety light grids and light curtains can be integrated into the safety concept of the machine or plant even under tight space conditions by virtue of their very compact design. These safety devices are also often used on presses to guard danger points or zones. Depending on the particular resolution of the safety light grids and curtains, protection of persons, hands or even fingers can be provided. SLG/SLC range safety light grids and light curtains achieve Control Category 4 to ISO 13849-1.
Design and mode of operation: On the SLB/SLC/SLG ranges of optoelectronic safety devices, the emitter and receiver are fitted in two separate enclosures. An invisible infra-red signal is sent from the emitter and this is picked up by the lens system of the receiver and evaluated either by an integral or external safety monitoring module. If the light beam is interrupted, the secure outputs are switched.
All of the optoelectronic safety devices listed here are maintenance-free and are characterised by simple fitting and adjustment.
Application: Two-hand control panels are non-separating protection devices. In general, they serve to ensure the machine operator's hands are located on the control panel when the control signal for a hazardous movement is issued. Two-hand control panels thus ascertain that intervention by the operator in dangerous moving processes is avoided when a machine or plant has been started.
The areas of application include presses for metal working, powder metallurgy, printing and paper processing machines, croppers and similar, as well as machinery in the rubber, plastic and chemical industries.
Two-hand control panels are the preferred protection devices for use in setting-up work and single-stroke operations for feed and removal processes.
Further information on the use of two-hand operation consoles and their evaluation is given in EN 574.
In order to achieve Category 0 to EN 60204-1, an additional signal evaluation circuit is needed. Safety monitoring modules for secure evaluation of signals from two-hand control panels and Emergency Stop devices are to be found in chapter xx.
Design and mode of operation: Two-hand control panels are protection devices, which require the simultaneous use of both hands for their actuation. By virtue of their forced location, both hands are kept out of the area of danger. In order to start and continue the operation of a machine or plant which can be dangerous, the location of the hands is controlled as long as danger can continue to be present.
The two-hand control panels are mounted as standard with an Emergency Stop push button to EN ISO 13850 and two operating units. In addition, there are guard hoods over the operating elements, which prevent simple manipulation of the protection function using hands, elbows, stomach, hips, thighs or knees, for example.
EN 574 differentiates between various types of two-hand switching circuits with regard to their technical degree of control security. In this respect, the selection of the type depends on the evaluation and the risk assessment.
Application: Together with other safety measures, consent switches are used to protect persons from potentially hazardous situations where machine guards need to be inactivated completely or in part in special operating modes.
These special situations will typically include setting up a machine, service work or observing processes. If the operator releases the button or - in the case of the 3-stage version - presses the button down completely through the middle setting, the control command is safely interrupted.
Application: Tactile monitoring systems stop the hazardous movement in case of contact or when touched. The variety of application fields require different safety devices.
Safety edges The safety edges of the SE range are suitable for safe-guarding crushing and shearing points, that can be present on guards, lifting tables and platforms, mobile storage shelving, operating process tables, storage lifts, lift doors, loading ramps, lifting and tilting devices or industrial gates. They immediately stop the dangerous movement, thus preventing physical injury or material damage.
Safety flaps Wide material input or feed areas on machines require a different approach to the protection of operating personnel and the machines themselves. Here, Safety flaps SL 300 are used.
Safety mats Safety mats are an additional form of protection for machines and plants, with the area in front of the danger zone fitted with the SMS switch mat. Depending on the shape of the area to be protected, multiple safety mats can be laid in line and electrically connected. When the safety mat is actuated, a signal is evaluated and the machine stop is initiated.
In combination with a suitable connected safety monitoring module, the three above-described systems achieve control category 3 respectively 1 or 4 to ISO 13849-1.
Design and mode of operation: The SE range safety edges consist of 3 basis elements, i.e. an aluminium profile, a rubber profile and a pair of plug-in sensors.
The deformation of the rubber profile safety edge is evaluated. The centrepiece is a fail-safe transmitter and receiver unit in both ends of the rubber profile. The deformation of the rubber profile strip weakens or interrupts the IR-signal between the transmitter and receiver units. The connected safety monitoring module evaluates the reduction of the IR signal and stops the hazardous movement. This measurement procedure, i.e. in conjunction with a connected safety monitoring module, complies with the safety requirements of control category 4 to ISO 13849-1. Solutions for applications of category 1 are also available.
EN 13856-2 resumes the requirements for safety edges and describes their design and homologation. Safety-related properties, such as operating temperature ranges, response times, forces, operating distances and stopping distances are defined in this Standard.
EN 13849-1 describes the guidelines for the design of safety-related components of the machine control.
The risk when using a local machine or unit must be determined. The requirements on the safety of the controller increases the higher the risk.
The safety edge system of the SE range with a connected safety monitoring module of the SE-400 C range complies with the safety requirements of control category 4. Even if there are 2 errors in the system, the safety edge will ensure a safe and efficient standstill of the machine or unit.
For applications of control category 1 to ISO 13849-1 the SE range safety edge can be connected to a safety monitoring module of the SE-100 C range.
When using a safety edge, it must be ensured that the speed of the hazardous movement is lower than the maximum starting speed of the safety edge. The stopping distance of the potentially dangerous parts and the profile-specific data must be adapted to each another. The stopping distance must not only be sufficient to bring the machine in the worst case situation to a standstill, but the maximum allowable force for vulnerable body parts must not be exceeded. Attention must be made during the planning to the counter-edge. If the possible run-on distance of the selected switch strip is not sufficient, the stopping distance of the machine must be shortened or a different switch strip profile should be used.
The required minimum run-on distance must be designed with the safety factor of at least 1.2. The safety factor must be even greater as soon as the run-on distance is influenced by other machine elements. (See also EN 13856-2 Annex C.)
SL 300 safety flaps consist of a flap and carrier profile and a position switch class 1. The actuation of the flap profile causes a positive break of the position switch, thus switching off the corresponding machine drive.
SMS 4/5 safety mats include 2 separate current carrying steel plates. The plates are held apart by insulating strips. The construction is moulded in Plastisol, a mechanically robust plastic that is highly resistant to chemicals.
Upon actuation of the safety mat, the inner steel plates are slightly bent. This causes an electrical short-circuit. This electrical short-circuit is evaluated by a downstream safety-monitoring module, which immediately initiates the machine shutdown.
Application: Safety foot switches are mounted on machines and plants as permissive switches in cases where manual operation is not possible.
Design and mode of operation: All safety foot switches are mounted with a shield to protect against unintentional operation. When the foot pedal is actuated to as far as pressure point, the NO contact is closed. If, in case of danger, the pedal is actuated beyond the pressure point, then the positive break NC contact is opened and mechanically latched. Reset operation is carried out by means of a push button. During the reset operation, the switch does not move through the switching-on point.
The safety foot switches conform to protection class IP 65.
Application: Easy, safe and reliable AS-Interface Safety at Work (SaW) is the first safety bus system based upon the open standard of AS-International. Safety components such as emergency stops, safety switches, solenoid interlocks or safety light curtains are simply interconnected through the AS-Interface profile cable. For the evaluation of the safety-related signals, only a safety monitor is required.
Design and mode of operation: AS-Interface Standard in accordance with EN 50295 With the integration of AS-Interface SaW the AS-Interface network will continue to operate unchanged. Well-known components, such as the standard AS-Interface master, the standard power supply as well as the AS-Interface unshielded 2-wire line can continue to be used and form the basis for integration of safety data transmission. An existing system can therefore be retrofitted with AS-i SaW safety components with ease.
The heart of safety The information of the safety components is transmitted through the AS-Interface network and monitored by the safety monitor. If a safety circuit is triggered or in case of failure of a safety component, the safety monitor puts the machine or installation safely to a hold position. The safety monitor is equipped with one or two redundant pairs of enabling paths for applications up to Control Category 4 according to ISO 13849-1. Each safety function of the monitor can be set with simple drag & drop software. The configuration is then transferred to the safety monitor and protected by a password.
Secure transmission mechanism The transmission mechanism for safety-related applications is based on the unchanged AS interface standard protocol. A defined telegram is transmitted for each master request by interaction between the safety monitor and the safety components. The monitor evaluates this information and opens the enabling paths if the target state is not met. The maximum reaction time for fail-safe shutdown is 40 ms
reduce costs with AS interface safety at work Reducing costs and effort - Who doesn't have to? During installation and machine commissioning as well as during maintenance, AS-Interface SaW supports the user with integrated system diagnosis. It provides detailed information about the cause and place of the failure, and enables the user to quickly find and analyse a malfunction and therefore minimise machine downtime. With AS-Interface Safety at Work you can directly reduce your costs.
More flexibility with AS interface safety at work For the realisation of individual safety solutions, SCHMERSAL offers the maximum amount of flexibility with its diverse range of safety devices. Depending on the application the user can choose the optimal solution out of an extensive product basket. As AS-Interface SaW is an open system, the user has also the possibility to include additional Safety components from other suppliers. AS interface safety at work adapts
Less installation time with AS interface SaW It doesn't get much easier and quicker that the AS-Interface SaW: select the safety component, connect using the AS-Interface flat-ribbon cable, configure the safety monitor, and you're done. No further settings need to be made on the safety components, complex wiring between the safety components and control cabinet is reduced and installation times are shortened. The power supply to the safety sensors is provided via the AS-Interface unshielded 2-wire line. With AS interface safety at work, you will reach your aim faster.
AS-Interface SaW System Features • Up to 31 standard and safety slaves on the AS-Interface system • No Safety PLC necessary • Safety-relevant signals can be allocated into groups and multiple Safety monitors may be connected • Response time is max. 40 ms • Safety-relevant signals can be integrated into plant diagnostics • Certified up to Control Category 4 in accordance with ISO 13849-1 • Certified by the TÜV (German Technical Inspectorate)
Application: The SHGV range is particularly suitable in more complex production systems and plants to protect divided maintenance and service doors which are used only rarely. Other applications include situations in which an electrical shock is possible, applications with higher ambient temperatures, specific uses in extreme ambient conditions and in chemical and process engineering in view of the explosion protection feature (see also Explosion-protected switchgear).
Design and mode of operation: The fundamental functional characteristic of a Trapped key system is that, depending on the operating state of the machine control system, the key is trapped and cannot be withdrawn either in automatic mode (guard locked) in a control element (e.g. key -operated selector switch) or, in the guard locking device, in a key tumbler cylinder, if the guard is open (in an electrically de-energised state).
The principle feature of the system is that the removable key is trapped either in the guard locking or in the key-operated selector switch.