Orderly System Shutdown; System Power Disconnect - Automation Direct DL205 Manual

Orderly System The first level of protection can be
Shutdown provided with the control program by
identifying machine problems. Analyze
your
shutdown sequences that must be
performed.
jammed or missing parts, empty bins,
etc. that do not pose a risk of personal
injury or equipment damage.
WARNING: The control program must not be the only form of protection for any
problems that may result in a risk of personal injury or equipment damage.
System Power By using electromechanical devices, such as master control relays and/or limit
switches, you can prevent accidental equipment startup. When installed properly,
Disconnect
these devices will prevent any machine operations from occurring.
For example, if the machine has a jammed part, the control program can turn off the
saw blade and retract the arbor. However, since the operator must open the guard to
remove the part, you must include a bypass switch to disconnect all system power
any time the guard is opened.
The operator must also have a quick method of manually disconnecting all system
power. This is accomplished with a mechanical device clearly labeled as an
Emergency Stop switch.
After an Emergency shutdown or any other type of power interruption, there may be
requirements that must be met before the control program can be restarted. For
example, there may be specific register values that must be established (or
maintained from the state prior to the shutdown) before operations can resume. In
this case, you may want to use retentive memory locations, or include constants in
the control program to ensure a known starting point.
application and identify
Typical problems
Guard Limit Switch
Installation and Wiring
any
are
Emergency
Stop
DL205 Installation and I/O Manual , Rev. B
2–3