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| designing to meet regs - "utilization category" |
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| Simon:
I am designing the electronics for a machine, this must meet the machinery directive part of which is EN 60204-1. This states that there must be a disconnect device such as a switch or connector. Where a connector is used it must be designed to be hot plugged/unplugged at maximum load. It also states that interlocks with the connector are also acceptable to trigger another switch of suitable utilization category. Now I already had a connector and knowing that no connector is really designed to be hot plugged/unplugged I already planned an interlock and was going to use signal pins in the connector that mate last and break first to control a MOSFET (well several in parallel). However the reg's have beat me to this and now my switch must meet the appropriate utilization category. Is it time to admit defeat and fit an off the shelf contactor, if I use something like a solid state relay with relevant ratings can I argue that my design therefore is of the correct category or would I need to have my switch separately validated? This is a 48V DC system. |
| 2N3055:
If I remember correctly you need physical disconnect device (a mechanical contactor or connector). No solid state devices because they can fail short.. |
| Simon:
That does make it a contactor then although EN60204 is not specific probably because separate standards about the utilization categories will state what can and cannot be used. |
| 2N3055:
--- Quote from: Simon on January 20, 2023, 09:20:24 am ---That does make it a contactor then although EN60204 is not specific probably because separate standards about the utilization categories will state what can and cannot be used. --- End quote --- Yes, unfortunately you need to go to specific details. But most will specify separate disconnect device in addition to normal on/off switch. I believe normal ON/OFF device can be solid state but security disconnect device must fail safe.. |
| AndyC_772:
--- Quote from: Simon on January 20, 2023, 09:01:21 am ---knowing that no connector is really designed to be hot plugged/unplugged --- End quote --- This is nonsense. (Trivial example: how do you turn on your kettle?) A disconnect device really does mean that - a device that can physically disconnect the supply, not a solid state, electronic switch. I recommend spending the afternoon looking through data sheets on the Molex web site. |
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