Operation
Theory of Operation
240 MagneMotion
Rockwell Automation Publication MMI-UM007F-EN-P - September 2020
motor are incorporated to help protect the motor and help minimize voltage increases. This
includes the Block Level Power Management, where excess power is dissipated through
unused motor blocks.
Power-Related Warnings and Faults when using QSMC Motor Controllers
The power distribution system experiences voltage drops when the motors draw power to
move vehicles and voltages increases during regeneration events when vehicles slow down.
These fluctuations can lead to the motor issuing warnings and faults and can cause motor
shutdown.
Soft Start
If the PTC used to limit inrush current heats up and goes into a high-resistance state, it does
not allow the propulsion bus to power up. To keep from overheating the internal soft start
resistor, the time between each successive turn on of the propulsion power must be a mini-
mum of 2 minutes and a minimum of 20 seconds between turn off and turn on (power cycle)
as shown in Figure 6-7.
Figure 6-7: Power Cycle Timing
To make sure that the soft start circuit resets for the next turn on:
• Wait a minimum of 2 minutes from turn on to turn on.
• Wait a minimum of 20 seconds from turn off to turn on.
• Wait for the Soft Start Off bit in the motor fault data to be set before turning the pro-
pulsion power back on. See either the Host Controller TCP/IP Communication Proto-
col User Manual, MMI-UM003, or the Host Controller EtherNet/IP Communication
Protocol User Manual, MMI-UM004.
Block Level Power Management
When the internal propulsion bus reaches +405V DC, current begins to ramp in the coils of
blocks that are available to allow the motor to absorb and dissipate unused power due to
regeneration within itself or coming from other motors that are connected to a commonly
shared +300–400V DC power supply. A coil block is defined as available and is used to dissi-
pate power within a motor if its neighboring blocks (upstream and downstream) do not have
Off
2 Minutes Minimum
20 Seconds
Minimum
On
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