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Trigger Hardware Operations Safety and Tips

The primary safety issue with the trigger system is the handling of trigger boards in the crates. Although the trigger and DAQ crates operate on +-5V and +-12V, the operating currents are running at >100A in some crates. Becuase the power supplies need to be able to deliver this level of currents, it will also happily drive large currents through accidental short circuits due to improper operation, which will at least damage the board and the crate backplane at the shorted areas with fair amount of smoke, and may even cause a fire. Besides the obvious safety hazard associated with this, the recovery from a damaged crate can be very complicated, so that  everyone performing the hardware operations are expected to be following the guide lines very closely.

Precautions for Operation

  • Think before you move and move slowly. This is the most general principle which applies to most hardware operations. Unlike some software tasks (or video games which can restart after game over), one mistake here can cause long delays of recovery or irrecoverable damage, or worst still personnel injury. 'Swift' movement actually hardly saves you any time and often causes you forgetting something or bumping/scraping on something which takes more time to redo or fix. Before any major movement, pause and ask yourself: "Is this what I really want to do ?"  
  • Check crate power and other activities. For any board insertion/extraction or non-trivial touch to cabling etc., the crate power must be off before such operations. Before turning on the crate, check activities around the rack to make sure noone is working on the rack (e.g. at the back of the rack). People working on non-trivial tasks around the crate other than simple board insertion/extractions should unplug the crate power cables.
  • Get to know what you are dealing with.  Many accidents are results of lack of awareness on the consequences of you actions. In our case, a good knowledge of the crate infrastructure and the difference of various types of boards, where they can go and where they should not is a crucial defense against mistakes.
  • Avoid using brute force.  Most tasks can be accompolished with the right tools and procedures without the need of brute force. Slips while exercising excessive force is a common source of injury, besides the obvious risk of equipment damage. Board insertion/ejection can be much easily done from learning using the latches. In some cases where forces are needed (e.g. some old boards don't have appropriate latches), it's generally still possible to make sure the setup 'feels' right before applying force. 
  • Resist temptation to cut corners.  Use the proper tools and equipment and follow  procedures. Reaching higher by standing on a chair with wheels ? Carrying too many things to save a trip ? Conveniently leaving things in an obviously unsafe position ?  Can all be tempting to save time, even though the risks are also clear.
  • Do not  'try/guess' on hardware.  When not sure this is the right place or procedure, it may be tempting to 'try'. The consequence can be irrecoverable or easily cost more time to recover than to make sure what you should be doing at first place. 
  • Take note of you activities.  Write down what you did systematically is essential for all hardware operations. Take a note of what was the settings before starting to change anything.    

 Trigger Hardware

       ( details to be added )
  Trigger and DAQ crates

( details to be added )



For comments, suggestions and questions to this page, contact Su Dong