Rockwell Automation SD3100 DISTRIB PWR SYS SD3100 DC PWR MODULE - Manual (Page 18)

2-4 SD3100 Power Modules
Control Power and Field Power Module Tap
The first (L1) and third (L3) phase of the incoming power are tapped off and fused to
provide single-phase AC power to the primary of the control power transformer and
the Field Power Module.
Field Isolation Transformer
A user-supplied field isolation transformer must be installed on the AC input of the
Field Power Module as described in section 3.4.1 of this manual. Using a field
isolation transformer provides the following advantages:
• Provides power matching to the Field Power Module.
• Permits the Field Power Module to continue operating in the event of a ground fault
in the field windings of the motor.
• Provides a known minimum AC input impedance for the snubbers to operate
against.
• Protects other circuits sharing the same power source from line notching
interference caused by the Field Power Module.
• Provides source impedance to guarantee SCR protection in the event of a short
circuit.
AC Line RC Suppressor
The optional AC line RC suppressor is a device used for limiting line voltage spikes
when the medium voltage source to the primary of the distribution transformer is
switched. This option is required for a primary voltage of 2300V or greater.
Output Inductor
Note that some systems may require an output inductor in series with the armature,
especially for some DC motors that do not have enough internal inductance for a
proper armature commutation process.
2.1.2.2 Armature Power Components
The armature power components convert the 3-phase AC input to a DC output used
for powering the motor armature.
The following components make up the armature power circuitry:
• armature SCR bridge (and its subordinate components)
• leg fuses
• gate coupler cards (GCCs)
• DC contactor