Rockwell Automation 294D ArmorStart LT Distributed Motor Controller DeviceNet Version - User Manual - Manual (Page 58)

58 Rockwell Automation Publication 290D-UM001A-EN-P - June 2012
Chapter 2 Installation and Wiring
Power Distribution The type of transformer and the connection configuration feeding an
ArmorStart LT Bulletin 294D plays an important role in its performance
and safety.
Delta/Wye with Grounded Wye Neutral
Figure 28 -
Delta/Wye with Grounded Wye Neutral is the most common type of
distribution system. The grounded neutral provides a direct path for common
mode current caused by the drive output.
AC Line Voltage Incoming voltage imbalances greater than 2% can cause large unequal currents
in a drive. An input line reactor may be necessary when line voltage imbalances
are greater than 2%.
Line Reactor In general, ArmorStart LT does not require line reactors. In most applications,
the ArmorStart LT is further away from the power distribution panel, therefore
the length of cable provides additional impedance as compared to an in-panel
solution.
Through design and engineering, the need for a line reactor is significantly
reduced.
Therefore, ArmorStart LT does not define a minimum line impedance
specification, and does not require a line reactor. Its design trades the external
reactor supplied by the customer for an internal fan integral to the controller.
This improves the overall life of the product. To achieve maximum electrical life
of Bulletin 294, an 800μH line reactor for the group can be applied to extend
total service life.
SHOCK HAZARD: ArmorStart LT requires the use of grounded Wye
power systems.