Orderly System Shutdown; System Power Disconnect - Automation Direct DL405 User Manual

Orderly System The PLC control program can provide
Shutdown the first level of protection when used to
identify
analyzing your application, identify any
shutdown sequences that must be
performed. Typical problems include
part jams, 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.
By using electro-mechanical devices such as master control relays and/or limit
System Power
switches, you can prevent accidental equipment startup. When installed properly,
Disconnect
these devices will prevent any machine operation from occurring.
For example, if the machine has a jammed part the PLC 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 disconnect switch that removes all
system power any time the guard is opened.
The machine operator must also have a quick and easy method of manually
disconnecting all system power. This is accomplished with a mechanical device that
is clearly labeled as an Emergency Stop switch.
Guard Limit Switch
After an Emergency shutdown or any other type of power interruption, there may be
requirements that must be met before the PLC 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.
machine problems.
Emergency
Stop
Installation and Wiring
After
Jam
Detect
Use E-Stop and Master Relay
Power On
E STOP
Master Relay Contacts
Master
Relay
Contacts
To disconnect PLC Power
Output
Master
Module
Relay
Contacts
To disconnect output
module power
2–3
Turn off
Saw
RST
RST
Retract
Arm
Master
Guard
Relay
Limit
Saw
Arbor