Design Guidelines
Transport System Design
86 MagneMotion
Rockwell Automation Publication MMI-UM002F-EN-P - October 2022
Electrical Wiring
The MM LITE motors are designed to operate at a nominal +36V DC. However, voltage
drops in the power distribution system when delivering power to the motors cause fluctuations
in the voltage that is seen at the motor power terminals. The power supplies and wiring for the
system must be designed to minimize these fluctuations. Block diagrams of MM LITE system
schematics are provided in Figure 3-8 and Figure 3-9. Any part numbers that are shown are
for reference only and are subject to change.
The acceptable voltage range for the MM LITE motors is between +27…42V DC, with a
nominal voltage of +36V DC ±10%. Operation below or above this range can result in the
motor turning off or being damaged. The motor has protections in place to help prevent dam-
age if the voltage limits are exceeded during operation. The power supply system must be
designed so that the voltage limits are not exceeded during normal operating conditions and
provide protection to the power supply if these limits are exceeded (see Electrical System on
page 326).
The MM LITE motors are enabled when the internal propulsion bus rises above +32V DC.
Until this voltage is reached, the motor reports an undervoltage fault and the motor does not
allow vehicle motion to occur. Once this internal voltage is reached, the motor can support
vehicle motion and operate as intended. If the internal bus voltage drops below +27V DC
during operation, the motor reports an undervoltage fault and all inverters within the motor are
disabled. Normal operation resumes once the internal propulsion bus rises back up to
+28V DC. If the internal bus voltage rises above +42V DC during operation, the motor
reports an overvoltage fault and all inverters within the motor are disabled. Normal operation
resumes once the internal propulsion bus falls below +38V DC. Once the inverters are dis-
abled, any vehicles in motion over the motor are no longer be under active control and as such
their motion is undefined.
Power Wiring
All power wiring must be constructed so there is minimal loss between the power supplies and
the motors (see Electrical System on page 326). The preferred architecture for the power bus
in a MagneMover LITE transport system is a number of T-splitters or junction boxes (shown
in Figure 3-8 and Figure 3-9) connected in series to form one low-resistance power bus with a
tap to each motor.
The current to each motor in a system at a given time depends on system behavior and vehicle
size. When determining the size of cable, the worst case power draw, current, and vehicle
motion must always be used. Designing the electrical system to keep voltage drops below 5%
of the nominal voltage (+36V DC) is recommended.
Vehicle motion consumes power when the vehicle accelerates. While the vehicle is accelerat-
ing, the motor is drawing power from the motor power supply system. In the worst case, a
motor can draw up to the value for peak power per vehicle while the vehicle is finishing its
acceleration.
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