Installation, Wiring,
and Specifications
2--4
Installation, Wiring, and Specifications
DL105 PLC User Manual, 3rd Edition
A properly rated emergency power disconnect should be used to power the PLC
controlled system as ameans of removing the power from the entire control system.
It may be necessary to install a capacitor across the disconnect to protect against a
condition known as “outrush“. This condition occurs when the output triacs are
turned off by powering off the disconnect, thus causing the energy stored in the
inductive loads to seek the shortest distance to ground, which is often through the
triacs.
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 i n
the control program to ensure a known starting point.
Ideally, the first l evel of protection can be
provided with the PLC control program
by identifying machine problems.
Analyze your application and identify any
shutdown sequences that must be
performed. Typical problems such as
jammed or missing parts, empty bins,
etc., create 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.
Turn off
Saw
Jam
Detect
RST
RST
Retract
Arm
This equipment is suitable for use in Class 1, Division 2, groups A, B, C and D or
non--hazardous locations only.
WARNING: Explosion Hazard! Substitution of components may impair
suitability for Class 1, Division 2.
Do not disconnect equipment unless power has been switched off or area is
known to be non--hazardous.
Emergency Power
Disconnect
Orderly System
Shutdown
Class 1, Division 2
Approval
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