Rockwell Automation 1395 DC Drive, 800-1250 Hp, FRN 5.XX-9.30 - Manual (Page 18)

Chapter 2
Hardware Description
2-5
SCR Packaging – SCR packaging in the 1395 consists of 1 hockey puck
type SCR.
Pulse Transformer/Snubber Boards – All four boards are identical and
are mounted directly to the armature bridge bus bars. R-C networks
contained on the board are used to protect the SCRs against voltage
transients (dv/dt).
DC Contactor – Output of the armature bridge is connected to the DC
motor through the main DC contactor M1 (Fig. 2.3). Coil voltage to M1 is
controlled by contacts from the pilot relay PR and external 115 VAC
control input entering at TB5-9 and -10.
NOTE: To provide DC Contactor energization a jumper or other external
circuitry must be connected to TB5-9 and -10.
Bridge Output Connections – Bridge output connections labeled A1 and
A2 (Fig. 2.3) correspond to the NEMA standards for connection to the A1
and A2 leads of the DC motor.
Field Bridge Components A general description of the components in the field bridge (Fig. 2.4) and
their operation is covered here:
Supply Voltage – In addition to being used for synchronization, the
three-phase voltage from fuses F11, F12 and F13 is sent to TB1 on the
Feedback Board where two of the three-phases are routed to the input of
the field supply power bridge (labeled Field L1 and Field L3 on Figure
2.4).
Field Current Feedback – Current transformer FCT provides field
current feedback information to the feedback board at TB-8 and -9. The
feedback board rectifies the single phase feedback and scales the DC
voltage using a burden resistor selected by the position of Jumper J1 on the
feedback board before being sent to the power stage interface. The DC
voltage representing field current feedback is passed directly through the
power stage interface and sent to the main control board.
Surge Suppression – Surge suppressor 3MOV protects the field power
bridge from high voltage line spikes and line surges on the incoming AC
line. 2MOV protects the motor field windings from line spikes on the
output of the field bridge.
Line Choke – Line Choke CH1 protects the field power bridge SCRs
from rapid rate of current changes.
SCR Modules – Field bridge SCRs are contained in modules made up of
two SCRs per package (PM1 and PM2).
Field Pulse Transformer and Snubber Board – The Field Pulse
Transformer Board provides the gate firing pulses and switching voltage
transient (dv/dt) protection for the field SCRs.
Bridge Output Connections – The output of the field bridge is connected
to TB2-1 and -2 which in turn is connected to the field leads of the motor.
The terminal labeled F+ on TB2 is connected to the F1 lead of the motor
and terminal F– to the F2 lead.