Rockwell Automation MV SMC Flex Motor Controller (for Series K or later) - Manual (Page 35)

Rockwell Automation Publication 1560E-UM051F-EN-P - June 2013 25
Product Overview Chapter 1
Functional Description The following functional descriptions and associated control circuits are for units
using IntelliVAC contactor control modules. For units with electromechanical
(relay) control, refer to
Appendix C .
Bulletin 1562E • Basic Control – Controlled Start only
When wired as shown in Figure 20 , the controller operates as follows:
Pressing the “Start” button initiates the start sequence. Relay “CR” closes and
applies control power to terminal 17 of the SMC Flex module. The Aux #4
(“Normal”) closes, energizing “M-IV” and “MCX”, which completes the hold-in
circuit on the start button, and closes the main contactor.
The SMC Flex module examines the line voltage, looks for fault conditions,
checks phase rotation, calculates zero crossing information, and begins gating the
SCRs to start the motor.
When the motor approaches rated speed, the SMC Flex module closes the
“Aux #1” (Ext. Bypass) auxiliary contacts, energizing “B-IV”, which closes the
bypass contactor. The motor then runs at full line voltage.
When the “Stop” button is pressed, the “CR” relay opens terminal 17 on the
SMC Flex module. The “Normal” contact opens, dropping out the main
contactor, allowing the motor to stop. The “Aux #1” contact is held closed for a
short time by the control module. This holds the bypass contactor closed for
about 10 seconds to protect the power electronics from any voltage transients due
to opening the motor circuits.
Bulletin 1562E • Basic Control – With Controlled Stop
When wired as shown in Figure 21 , the controller operates in much the same
manner as in Figure 20 .
Terminal 16 on the SMC Flex module now controls the start and stop
maneuvers. Terminal 16 must remain energized for the module to run. When the
“Stop” button is pressed, and “CR” opens, the SMC Flex module will initiate the
option stop. An uncontrolled, or coast stop, is achieved by opening the
connection to terminal 17. This contact should remain open to ensure all hold-in
contacts clear, to prevent a re-start.
ATTENTION: The control circuit schematics shown below assume that control
power is fed from the same source as the primary circuit. If external control
power is used, additional control interlocking may be required to avoid
unexpected motor start-up. The control interlock should ensure that a motor
start request is not inadvertently applied when the primary circuit is
disconnected.