kamenges
Member
We are finishing up a machine for delivery to the England. Since we don't do this very often we had a CE consultant in to evaluate the machine relative to several directives.
One of the items he found that we were not compliant with was concerning the normal stop function relative to the EHSR directive. According to EHSR 1.2.4.1, "Once the machine or its hazardous functions have stop, the energy supply to the actuators concerned must be cut off". The way the consultant seemed to be treating it, a normal stop is just an e-stop with a more gradual decel rate. That just seems a little odd.
I guess the question would be what constitutes energy being cut off from an actuator? For example, if a drive is disabled but not put into STO, is that considered having the energy cut off? If an air cylinder is retracted by a 2-position valve that is turned off as part of the stop, is that considered energy cut off?
OR are we talking about a contactor or relay (as appropriate) interrupting the energy source to the actuators? This would seem to be what is done in an e-stop.
Then, to add a little more latitude to the situation, you have EHSR 1.2.4.2, which talks about an operational stop. But this requires monitoring of the stopped condition. What are the requirements of this monitoring?
The thing that adds a little more frustration is that the whole machine is enclosed in a guard enclosure with monitored access points (doors with safety switches). We can easily bring the machine to a full stop before an operator could get to any hazards if a door is opened while the machine is running. We feel confident that the safety portion of the guard system is effective and reached the needed performance level. But relative to 1.2.4.2, this really wouldn't be monitoring the stop condition. It would be preventing access to the machine in an operational stop condition and rendering it safe if the guarding is violated. That doesn't seem to directly satisfy 1.2.4.2 but it logically seems safe?
How do you guys approach this problem? Is my consultant reading too much into the intend of the directive?
Thanks,
Keith
One of the items he found that we were not compliant with was concerning the normal stop function relative to the EHSR directive. According to EHSR 1.2.4.1, "Once the machine or its hazardous functions have stop, the energy supply to the actuators concerned must be cut off". The way the consultant seemed to be treating it, a normal stop is just an e-stop with a more gradual decel rate. That just seems a little odd.
I guess the question would be what constitutes energy being cut off from an actuator? For example, if a drive is disabled but not put into STO, is that considered having the energy cut off? If an air cylinder is retracted by a 2-position valve that is turned off as part of the stop, is that considered energy cut off?
OR are we talking about a contactor or relay (as appropriate) interrupting the energy source to the actuators? This would seem to be what is done in an e-stop.
Then, to add a little more latitude to the situation, you have EHSR 1.2.4.2, which talks about an operational stop. But this requires monitoring of the stopped condition. What are the requirements of this monitoring?
The thing that adds a little more frustration is that the whole machine is enclosed in a guard enclosure with monitored access points (doors with safety switches). We can easily bring the machine to a full stop before an operator could get to any hazards if a door is opened while the machine is running. We feel confident that the safety portion of the guard system is effective and reached the needed performance level. But relative to 1.2.4.2, this really wouldn't be monitoring the stop condition. It would be preventing access to the machine in an operational stop condition and rendering it safe if the guarding is violated. That doesn't seem to directly satisfy 1.2.4.2 but it logically seems safe?
How do you guys approach this problem? Is my consultant reading too much into the intend of the directive?
Thanks,
Keith