Rockwell Automation 2098-IPD-xxx Ultra5000 Intelligent Positioning Drives Installation Manual User Manual
Page 148
Publication 2098-IN001E-EN-P — April 2002
D-2
Wiring Three Phase Power to a Single Phase Ultra5000
Mandatory Neutral
Connection of Isolation
Transformer
A neutral must be connected (shown in the upper diagram of
) when single phase drives are attached to a three phase isolating
transformer secondary. It is not necessary that all three phases be
loaded with drives, but each drive must have its power return via the
neutral connection.
Failure to connect the neutral (shown in the lower diagram of
) can result in supply voltage swings at the individual loads (i.e.,
drives). This occurs when the neutral point moves vectorially as a
result of load variations normally experienced by the individual
drives. The supply voltage swing may cause undervoltage and
overvoltage trips on the drives, and the drive can be damaged if the
overvoltage limit is exceeded.
Figure D.1
Mandatory Neutral Connection with Safety Ground of Isolation Transformer
Load 1
Load 2
Load 3
Phase 1
Phase 3
Phase2
Any unbalance in load currents will result in unbalanced voltages which could
exceed the voltage limit of the load.
Safety
Ground
Load 1
Load 2
Load 3
Phase 1
Phase 3
Phase 2