What is negative operation and positive operation?
|(A) Negative operation||(B) Positive operation||(C) Combined operation|
|Safety||Never use negative-operation switches alone in safety applications.||Positive-operation switches are recommended when used alone as the switches offer a higher level of safety than negative-operation switches.||Switches in combined operation offer an even higher level of safety than positive-operation switches alone.|
|Category||Category B or 1|
(using approved parts)
|B, 1, 2, 3, 4||B, 1, 2, 3, 4|
|Normal operation||Abnormal operation||Normal operation||Abnormal operation||Normal operation|
|a) No reset due to contact welding|
|a) Contact not open due to cam abrasion|
|Contacts closed (door closed) |
|b) No reset due to spring damage|
|b) Contact not open due to improper cam position (door open) ||Contacts open (door open) |
|Opened by built-in spring.||Opened directly by externally operating unit like cam or dog.||Opened by a negative- and positiveoperation combination.|
|NO contacts||NC contacts ||NO and NC contacts |
|Pros||The negative operation is a fail-safe operation that ensures safety in case of cam abrasion, improper cam positioning or unexpected cam removal.||The actuator forcibly opens contacts if a contact welds or a spring is broken.||A negative- and positive-operation combination eliminates the disadvantages of both modes.|
|Cons||The actuator may move accidentally with unexpected force and close the contacts. The result may be a relatively dangerous situation.||There is a danger that contacts may close due to cam abrasion, improper cam positioning or unexpected cam removal.||The safety switch circuit may work normally for a while if one of the switches fails to operate.|
For Safety Light Curtain Robust & Basic New Lineup. Understanding the Indicators at a Glance.
Compact (104.5 mm), lightweight (1.3 kg) and easy-to-install Safety Laser Scanner
Supports ISO 13849-1 (PLe/Safety Category 4). Can be used on higher risk level applications by connecting to Safety Controllers.