Field bridge components – Rockwell Automation 1395 Digital DC Drive FRN 5-10.10/9.30 User Manual
Page 27
Chapter 2
Hardware Description
1 – 30 HP, 230VAC 2 – 60 HP, 460VAC
2-5
Field Bridge Components
A general description of the components in the field bridge (Fig. 2.4) and
their operation is covered here:
Supply Voltage – Two of the three supply voltage phases are routed to the
input of the field supply power bridge (TB1-1 and TB1-2).
Field Current Feedback – Current at transformer FCT provides field
current feedback information to the PSI/Switcher board. The PSI/Switcher
board rectifies the single phase feedback and scales the DC voltage using a
burden resistor selected by the position of Jumper J1 on this board. The
DC voltage representing field current feedback is sent to the main control
board.
Surge Suppression – Surge suppressor MOV5 protects the field power
bridge from high voltage line spikes and line surges on the incoming AC
line. MOV6 protects the motor field windings from line spikes on the
output of the field bridge.
Inductor – Inductor L1 protects the field power bridge SCRs from rapid
rate of current changes (di/dt).
SCR Modules – Field bridge SCRs are contained in one single phase full
wave module (PM7).
Field Pulse Transformer – The Field Pulse Transformers on the Power
Board provide the gate firing pulses for the field SCRs.
Voltage Transient Protection – RC networks contained on the power
board are used to protect the SCRs against voltage transients (dv/dt).
Bridge Output Connections – The output of the field bridge is connected
to the Power Board. Connections of the motor field is at TB1-3 and TB1-4
on the Power Board.
Figure 2.4
Field Bridge Components
TB1
1
2
3
4
L1
F(–)
F(+)
L3
2
L1
F2
F1
MOV5
7
6
9
1
4
8
MOV6
3
On Power Board
On
Power
Board
J1
J2
To PSI / Switcher Bd J5
FCT
1
2
FCT–2
FCT–1