Rockwell Automation 150 MNL/SMC DIALOG+/APP-PROD GUIDE - Manual (Page 134)

5-10 SMC Dialog Plus Controller Special Application Considerations
Altitude De-rating Because of the decreased efficiency of fans and heatsinks, it is
necessary to de-rate the SMC Dialog Plus controller above 6,500 feet
(approximately 2,000 meters). When using the controller above
6,500 feet, use the next size device to guard against potential over
temperature trips.
Isolation Contactor When installed with branch circuit protection and an overcurrent
device, SMC Dialog Plus controllers are compatible with the National
Electric Code (NEC). When an isolation contactor is not used,
hazardous voltages are present at the load terminals of the power
module even when the controller is turned off. Warning labels must
be attached to the motor terminal box, the controller enclosure, and
the control station to indicate this hazard.
The isolation contactor is used to provide automatic electrical
isolation of the controller and motor circuit when the controller is
shut down. Shut down can occur in either of two ways: either
manually, by pressing the stop button, or automatically, by the
presence of abnormal conditions (such as a motor overload relay trip).
Under normal conditions the isolation contactor carries only the load
current. During start, the isolation contactor is energized before th
SCRs are gated “on.” While stopping, the SCRs are gated “off”
before the isolation contactor is de-energized. The isolation contactor
is not making or breaking the load current.
Figure 5.6 Typical Connection Diagram with Isolation Contactor
Power Input
3-Phase
Branch
Protection ➀ SMC Dialog Plus Controller ➁
L1/1
L2/3
L3/5
T1/2
T2/4
T3/6
Motor
➀
➀ Customer supplied
feature of the SMC Dialog Plus controller.
➁ Overload protection is included as a standard
Isolation Contactor
(I.C.) ➀
Fast-Acting
SCR Fuses
(optional) ➀