EU European Union

Are You Ready? WEEE Directive Full Implementation Starts 15-Aug-18

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Processing of waste electrical and electronic materials

Many man­u­fac­tur­ers selling indus­tri­al products into the EU mar­ket have come to under­stand at least one of the envir­on­ment­al pro­tec­tion Dir­ect­ives, RoHS – the “Restric­tion of the Use of Cer­tain Haz­ard­ous Sub­stances.” In this post, I’m going to be look­ing at anoth­er envir­on­ment­al dir­ect­ive: WEEE – the “Waste Elec­tric­al and Elec­tron­ic Equip­ment” Dir­ect­ive (2012/19/EU). The WEEE Dir­ect­ive requires […]

Control Functions

Trapped Key Interlocking

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This is a trapped key interlock on the door of an electrical switchgear cabinet. To open the door the key must be inserted and turned to withdraw a bolt that holds the door closed. With the bolt withdrawn, the key is held in the lock. The upstream switching device is held open by another interlock using the same key; since the key can only be in one of the two locks, it prevents accidentally closing the upstream switch while the cabinet is open for maintenance. The interlock is attached to the door with one-way screws to discourage casual removal of the lock, which would defeat the system.
This entry is part 3 of 7 in the series Guards and Guard­ing

Many machine design­ers think of inter­locks as exclus­ively elec­tric­al devices; a switch is attached to a mov­able mech­an­ic­al guard, and the switch is con­nec­ted to the con­trol sys­tem. Trapped Key Inter­lock­ing is a way to inter­lock guards that is equally effect­ive, and often more appro­pri­ate in severe envir­on­ment­al con­di­tions. Copy­right secured by Digi­prove © 2018Acknow­ledge­ments: As cited.Some Rights ReservedOri­gin­al con­tent here is pub­lished under […]