Machine Safety Matters

July 14, 2011
Comprehensive Solutions Advance, Devices Get Smarter, but There Still Are Plenty of Hindrances and Concerns

The results of our most recent Control Design audience study about readers' use of safety components and systems provided a few changes from a similar 2008 study.

Asked who decides what and how much safety equipment the machines will need, 57% of the respondents said the machine builders make those choices; 28% say it's the end users; and 15% say system integrators (SIs) decide. In 2008, only 42% of machine builders decided; 32% of end users decided; and 25% of SIs made the decision on machine safety.

When asked how their safety systems are connected and networked, 81% reported that they use a hardwired system, while 19% said they use digital networking. This is a noticeable shift from 2008, when only 13% used digital networking for safety.

This year's study asked about the audience's biggest machine safety design headaches. Some 48% reported that it's hard to know what standards and regulations to apply. Another 29% say their worst problem is dealing with operators who try to defeat the safety system; and 22% surprisingly said that fully operational safety systems were thought to impede productivity.

Respondents reported getting their guidance on machine safety and applicable standards information from a variety of sources. For example, 61% said they get safety guidance and standards from OSHA; 50% get it from NFPA; 44% use ANSI standards; 40% from IEC; 33% from ISO; and 27% from EN. These results were pretty much the same as two years ago, although more respondents seem to be seeking help from organizations other than OSHA, which doesn't offer direct guidance on standards.

Standards uncertainty (32%) and technical concerns (28%) were two of the biggest hindrances to implementing an integrated system. The respondents also indentified customer resistance (18%), liability concerns (13%) and technical support (9%) as major hinderances.

Safety PLC
Pluto safety PLC has an All Supervisor concept that achieves and maintains Category 4/SIL 3/PLe safety levels for safety applications where faults must not lead to loss of a safety function. All inputs and outputs are separately connected to each processor. The processors continuously compare results to ensure integrity of data. A single Pluto can monitor up to 150 dynamic safety devices.
Jokab Safety
Monitor Safety
ESR5 safety relay monitors the signals from safety devices and switches off quickly in an emergency. With redundant features, the ESR5 is compatible with emergency stops, rope pulls, two-hand control stations and others, and detects ground fault, cross connection fault or wire breakage. It is available in single- and dual-channel versions.
Master Safety
Guardmaster safety relays meet EN ISO 13849-1 and include six basic units. The relays have a single-wire communication capability that helps eliminate dual-channel connection between relays. Users can expand and cascade safety functions up to a SIL 3 rating using a single wire to connect between relays. AND/OR logic can be set via a rotary switch on the front of the relay for configurations including regional and global e-stop architectures.
Rockwell Automation
Solid Dold
LG5924 Series Dold relays are single-channel, e-stop relays with 24 Vdc, 110 Vac and 230 Vac coil voltages, and with internal positive temperature coefficient resistor short-circuit protection. Output options include either two normally open contacts, or three normally open and one normally closed contact. The normally open contacts are safety contacts. LG5925 Series relays are dual-channel, e-stop/safety gate relays designed for applications with emergency stop buttons and safety gates.

Access Control
Light version of Electronic Key System (EKS) is a transponder-based access control that provides parameter assignment for the keys via a programming station on a PC, provides security with an infinite number of key tag combinations (116 byte), and is not affected by magnetics.
Euchner USA

  Add-On Safety
Diagnostics Add-On Instruction for CompactLogix and ControlLogix controllers, available as a free download, is designed to enable PLC programmers to retrieve detailed diagnostic data from an AS-Interface safety monitor, and to be compatible with competitive AS-Interface Safety at Work safety monitors.

Safely Configure Safety
PSR-TriSafe safety controller monitors up to 20 safety input signals. Configuration uses SafeConf software with drag-and-drop interface to integrate new safety equipment. The software's simulation mode allows testing of the safety design without connecting the hardware. The software is available for free download.
Phoenix Contact

Don't Lose Your Head
HS5D compact interlock safety switches available with three contacts monitor if the head is separated or improperly mounted on the body. The switches are available with metal or plastic heads; the metal head can be rotated eight ways based on actuator entry, providing mounting flexibility.

Chances Are Slim
D4GS-N Slim safety door switches are 17 mm wide, provide IP67 protection, and have a tongue-actuated design for skinny spaces subject to water washdown. An operation key with rubber mounting holes absorbs vibration and shock. The switches are rated for a minimum of 1 million mechanical operations and 100,000 electrical operations, are vibration-resistant 10-55 Hz, and shock-resistant to at least 1,000 m/s2.
Omron STI
Safety Guide
Interface and Intrinsic Safety Quick Reference Guide of the company's intrinsically safe products includes switching amplifiers, analog I/O, solenoid drivers, rotational speed monitors, and relays and power supplies. The guide allows users to select the correct amplifier for a specific application, and showcases unique, out-of-the-panel solutions for intrinsic safety.

TwinSafe Terminals for EtherCat I/O are rated for SIL 3, conform to IEC 61508 and EN ISO 13849-1 PLe, and are certified for North America. EL6900 safety PLC terminal can integrate 128 four-channel safety terminals (512 safety devices) and process 256 safety-relevant function blocks. A connection shutdown function permits interchangeable sections of equipment with safety terminals installed to be removed from the machine without causing safety system errors.
Beckhoff Automation

Par for Safety Course
Profisafe modules with iPar functionality support automatic download of parameters to the respective controller via Profisafe-compliant iPar server. Parameters can be set, backed up and documented using Wago-Safety-Editor. The new modules support the tool calling interface (TCI) up to Conformance Class 3, so the Safety-Editor can be integrated into corresponding TCI-compatible engineering systems. The modules can be used with both Profibus and Profinet.

Motor Monitor
Relay-free SafeMC safety circuit installed in all Acoposmulti drive units automatically monitors motor response to instructions from the servo drive, using digital encoders certified to EN ISO 13849. The electronics are integrated directly on the drive to avoid increasing response times. Acoposmulti with SafeMC can be integrated in the existing system with the SafeLogic safety controller and the X20 Safe I/O.
B&R Industrial Automation

Fail Safe
Fail-safe modules for ET 200iSP intrinsically safe distributed I/O system, 8F-DI Ex Namur, 4F-DO Ex 40mA/17.4V, and 4F-AI Ex HART meet safety requirements in accordance with IEC 61508 to SIL 3, ISO 13849-1 to PLe. The modules are suitable for applications including emergency shutdown (ESD), boiler protection or fire and gas equipment.
Siemens Industry

Most Irregular
AG4 safety laser scanner uses pulses of Class 1 infrared laser light to locate objects in its field of view. It safeguards irregularly shaped areas not suitable for a standard two- or three-piece safety light screen and meets requirements for Type 3 per IEC 61496-1/-2, Category 3 PLd per EN ISO 13849-1, and SIL 2 per IEC 61508.
Banner Engineering

Safety PLC
eloProg programmable safety controller monitors inputs such as photoelectric sensors, light curtains, magnetically operated sensors, emergency stop buttons, etc., and lets the user program the function of these inputs using icon-based software to create specific logic to control the safety outputs. The eloProg base module can be combined in multiple configurations with other modules or can be operated standalone.
Elobau Sensor Technology

Failsafe Alarm
STA safety trip alarm accepts signal input from transmitters, temperature sensors, resistance and potentiometer devices, and other monitoring and control equipment. It provides three failsafe alarm outputs, and is certified to IEC 61508: Parts 1, 2 and 3 by TÜV Rheinland for single use in Safety Instrumented Systems up to SIL 2.
Moore Industries

Arc Alert
PGR-8800 arc flash relay protects electrical systems by detecting arc flash incidents early in a standalone format with up to 24 sensors, including optional fiberoptic cable sensors. It detects excessive current and light, which is the earliest warning sign of an arc flash.

Change Channels
Each channel of Safety Manager Remote Universal Safety IO can be configured individually to a different I/O type. Each module has a capacity of 32 configurable channels, and up to 28 redundant modules can be connected to a Safety Manager using the SIL 3-certified Safety Manager Remote I/O communication network.

Always On Edge
Pressure sensing Edge product line is engineered to EN17601 standards, Fail-Safe protected, and available in different colors, lengths, sizes, mounting types, profiles and sensitivities; with front, side and angled actuations; bendable properties; curved or custom-engineered edges.

Sights and Sounds
LKEH Series combines LED light tower with an audible horn integrated into the base, and is offered with pre-installed sounds or with MP3 field-programming capability. Volume is adjustable from zero up to 105 dB at 1 m.

Simplify Safety
Universal Safety Controller Hub replaces multiple individual safety relay modules with one integrated safety center. The hub contains dry-contact safety relays and solid-state outputs. Safety channels A and B are pulsed independently and sequentially to protect from component and internal shorts of four-wire e-stop devices.
Pinnacle Systems

Cable Security
Model RS cable-operated safety-stop switches detect whenever the actuation cable is severed or pulled. The double-ended unit maintains constant tension on the pull cable. If the cable is pulled or the cable breaks, the handle rotates and activates the microswitch.
Conveyor Components

Slim Housing
E-Box for RAFIX 22 FS-type actuators has a yellow housing cap for e-stop buttons or a gray cap for push buttons or selector switches. E-Box is suited for installation on 40 mm profile rails. Contact modules are available with gold contacts for 35 V and 100 mA or silver contacts  for 250 V and 4 A.
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