ccaserta
Specifier/Regulator
- Feb 21, 2002
- 105
I'm a compliance Engineer and have a detailed question regarding electrical enclosures. When I have a customer that has a very large system and requires several connected enclosures (e.g. Hoffman enclosure with a master door,)I seem to always run into an issue that is not easily solved.
In EN 60204-1, clause 6.2.2 b) "Protection for Enclosues" the requirement states that the doors can only be opened when the Disconnect device is opened. "so far no problem"
The Disconnector can only be closed when the door is closed. Then a little further down it states, that upon closing the door the interlock must be restored. When more than one door can provide access to live parts, care should be taken to implement this intent. " this is the problem"
The master door meets this requirement but the other two or more doors can be left opened. When I come into the picture at a customer site the electrical panel has already been laid out. Most electrical engineers would not even consider electrically interlocking the doors because most large machinery has a large current draw, it requires a huge contactor and there is not enough real estate in the panel.
Mechanically, Hoffman or anyone else we've been able to find makes a mechanical interlock that guarantees that the Disconnector can only be closed after all the doors are closed.
Has anyone found a solution to this clause besides "service persons are trained to enter the enclosure". Please keep in mind this does not guarantee that the interlock will be restored on all the doors the same as the master door. As an ispector this is a real pain, I understand the issue for the machine manufacture and most of the time I end up giving in to some form of training and documentation because I don't have a solution. I try to be as reasonable as I can and still meet the standards requirements for my customers. I think this is an important problem that shouild not be ignored. Sorry for the long thread but it's driving me nuts. Christopher Caserta
ccaserta@enorthhampton.com
Ph:904-225-0360
In EN 60204-1, clause 6.2.2 b) "Protection for Enclosues" the requirement states that the doors can only be opened when the Disconnect device is opened. "so far no problem"
The Disconnector can only be closed when the door is closed. Then a little further down it states, that upon closing the door the interlock must be restored. When more than one door can provide access to live parts, care should be taken to implement this intent. " this is the problem"
The master door meets this requirement but the other two or more doors can be left opened. When I come into the picture at a customer site the electrical panel has already been laid out. Most electrical engineers would not even consider electrically interlocking the doors because most large machinery has a large current draw, it requires a huge contactor and there is not enough real estate in the panel.
Mechanically, Hoffman or anyone else we've been able to find makes a mechanical interlock that guarantees that the Disconnector can only be closed after all the doors are closed.
Has anyone found a solution to this clause besides "service persons are trained to enter the enclosure". Please keep in mind this does not guarantee that the interlock will be restored on all the doors the same as the master door. As an ispector this is a real pain, I understand the issue for the machine manufacture and most of the time I end up giving in to some form of training and documentation because I don't have a solution. I try to be as reasonable as I can and still meet the standards requirements for my customers. I think this is an important problem that shouild not be ignored. Sorry for the long thread but it's driving me nuts. Christopher Caserta
ccaserta@enorthhampton.com
Ph:904-225-0360