Rockwell Automation 1395 Digital DC Drive FRN 5-10.10/9.30 - Manual (Page 44)

Chapter 3
Hardware Description
40 – 100 HP, 230VAC
75 – 200 HP, 460VAC
3-4
Surge Suppression – Surge suppressor 1 MOV (Fig. 3.2) protects the
armature power bridge from high voltage line spikes and line surges.
Line Chokes – Line Chokes CH2 through CH7 are used to protect the
power bridge SCRs in each of the six legs of the power bridge from rapid
rate of current changes (di/dt).
SCR Packaging – SCR packaging in the 1395 in bridge ratings 111 – 345
consists of 2 SCRs per module.
Pulse Transformer/Snubber Boards – All three 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 Current Sensing – DC overcurrent sensing is provided using DC
transducer TD1 (Fig. 3.3).
Figure 3.3
Armature Bridge Components (OUTPUT)
To Pulse Transformer &
Snubber Board A2
To Pulse Transformer &
Snubber Board A3
To Pulse Transformer &
Snubber Board A4
To Feedback
Board
TB1-1, 2
To Feedback
Board
TB1-20, 23
4R
1F
G2 G1
6R
3F
G2
G1
G2
G1
2R
5F
2F
G2
5R
G1
6F
G2
3R
G1
1R
G1 G2
4F
DC Contactor – Output of the armature bridge is connected to the DC
motor through the main DC contactor M1 (Fig. 3.3). Coil voltage to M1 is
controlled by contacts from the pilot relay PR and external 115VAC
control input entering at TB2-3.
Bridge Output Connections – Bridge output connections labeled A1 and
A2 (Fig. 3.3) correspond to the NEMA standards for connection to the A1
and A2 leads of the DC motor. If dynamic braking is used, the dynamic
braking resistor bank is connected to terminals DB1 and DB2.