Let Manufacturing Services and Installation upgrade your plant safety with the latest innovations in Light Curtain Technology with :
- Resolutions of 14mm, 20mm, 30mm, 40mm, and 90mm
- Protection fields of 160 mm to 1810mm
- Integrated contractor monitoring (EDM)
- Integrated start/restart interlock
- Dual 50omA PNP safety outputs
- Ranges up to 60 meters
- Master-Slave interconnection capability
- Plug-in, quick-connect cables
- Integral 7-segment LED for status monitoring, ease-of-installation, and fault diagnostics to minimize downtime
- IP65 ingress protection rating
- Optical synchronization for ease-of-alignment during installation
- Rugged, powder-coated aluminum housings
- Certification to IEC/EN 61496-1 and IEC/EN 61496-2
- UL and CSA -listing
- What is a light curtain?
- Where are they used?
- What are the functional safety requirements?
- What are the a pplication requirements for Light Curtains
- What are the four most common muting sensor configurations?
The Light Curtains we install are manufactured by Schmersal and are available in 2-beam, 3-beam and 4-beam designs.
Muting Safety Light Curtains: Applications & Use by Technical Staff at SCHMERSAL, INC.
What is a Muting Safety Light Curtain?
A muting safety light curtain permits the safety (protection) function to be temporarily disabled for reasons related to the equipment or machine work cycle.
Such disabling of the safety function for a limited period of time is referred to as “muting”.
Where are Light Curtains typically used?
While there are a wide variety of situations in which the muting function may be necessary, there are two basic applications that can be considered as typical.
(1) To permit the access of personnel inside the hazard-ous area during the non-hazardous portion of the equipment cycle … for example, removal or repositioning of the work piece.
(2) To permit the access of materials of production and prevent access by personnel … for example, pallet entrance and/or exit from the hazardous area
Functional Safety Requirements for Light Curtains
(1) The muting function is a temporary interruption of the safety (protection) function that must be activated and de-activated automatically.
(2) The safety category of the device, or of the part of the circuit that implements the muting function, must be the same as that of the safety function that disables so as not to compromise the protection of the entire system.
(3) Activation and subsequent de-activation of the muting function must be achieved using two or more hard-wired and independent signals activated by a proper time or space sequence.
(4) It must not be possible to activate the muting function when the Electro-Sensitive Protection Equipment (ESPE) has the safety outputs de-activated.
(5) It must not be possible to initiate a muting function by switching the device “off” and then “on” again. For example, a fault to ground or power outage to which the muting sensors are connected must not cause a muting condition. Similarly, if the ESPE is already in the muting state, the temporary loss of power must return the muting outputs to an “off” state (de-activated). Access can only be achieved by a manual override command.
Application Requirements for Light Curtains
(1) Muting must only be activated at an appropriate point in the machine cycle … for example, when there are no risks to personnel.
(2) Any residual risks must be carefully assessed.
(3) Suitable measures must be taken to prevent, to the degree possible, any attempt to defeat the protection.
(4) Where practical, the possibility of a person remaining undetected inside the hazardous area on re-activation of the muting phase must be avoided.
(5) Muting sensors must be mechanically protected to avoid impacts that could compromise their alignment. Specific Requirements for Access Control in Palletizing and Goods Handling Systems
(1) The material, and not the pallet, must be sensed … otherwise a person could pass through the access point riding on a pallet.
(2) Muting time must be restricted to the effective transit time of the material through the access point.
(3) The clearing of the protection zone of the ESPE can-not be the sole condition for disabling the muting func-tion.
(4) The muting function must be time-restricted.
(5) A misalignment of the muting sensors, which pro-duces an effect similar to activation, must not allow the muting condition.
(6) The configuration chosen for the muting sensors, and their positioning, must allow a safe discrimination be-tween personnel and material.
(7) The layout of the access point, and the positioning of the muting sensors and the side guards, must not per-mit the transit of a person toward the hazardous area during the muting phase … and for the entire time dur-ing which the pallet transits through the access point.
Four Most Common Muting Sensor Configurations
The four most common muting safety light curtain configurations are:
• Four (4) muting sensors with timing control
• Four (4) muting sensors with sequence control
• Two (2) cross-beam muting sensors and timing control
For more information, vist http://schmersalusa.com/technical_articles.asp