Tuesday, September 23, 2014

Start & Stop Controls


The CSA Standards outline requirements for operator controls.  One of the ones that affects almost every machine we assess are the start and stop controls.  The standard calls for a stop control beside every start control.  This seems simple enough, but you would be surprised as to how many machines do not meet this requirement.

One of the most common things we come across is that there is a start control, but an emergency stop is being used as the stop control.  The emergency stop usually does not meet the requirements as well.  It might not be self-latching and might be a push button control.  It also might be located in a different location than the start control.  Machine controls are a critical component of machine safety and it’s important that an operator know what button does what.  Having a clear start control and stop control, and a separate emergency stop are important.  Further, that emergency stop should function correctly and meet the requirements for the standard as well.

On smaller older pieces of equipment it is common to have a standard starter circuit for any electric motors.  These starters function similar to a light switch, they are either on or off.  This can provide a significant risk during a power failure (like a breaker trip).  The equipment will stop, but when power is restored if the machine is still in start mode it will power up again automatically.  This can surprise and potentially injure an operator not prepared for this.  Magnetic starters are designed to return to a defined normal position (off in most cases) when power is removed.  These provide added safety protection to the operator.

Finally one of the other common items we come across during assessments is worn labelling.  Since start and stop are the most common buttons pushed on most machines, the labelling can sometimes wear off.  No one thinks to fix this, because the main operator knows these buttons without needing the labelling.  Put yourself in a new operator’s position, will they know where start is?  And more importantly will they know where stop is, especially in a situation where they need to find it quickly.

start stop controls

Posted by Kristin Petaski at 8:58 AM 0 Comments
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