Service Bulletin
1397 400-600 HP SCR Replacement Procedure
This publication will guide you through replacement of a 1397 SCR
assembly. For additional drive information, refer to the 1397 User Manual,
publication 1397-5.0.
Replacement Procedure
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!
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ATTENTION: The drive contains ESD (Electrostatic
Discharge) sensitive parts and assemblies. Static control
precautions are required when installing, testing, servicing or
repairing this assembly. Component damage may result if ESD
control procedures are not followed. If you are not familiar with
static control procedures, reference A-B publication 8000-4.5.2,
“Guarding Against Electrostatic Damage” or any other
applicable ESD protection handbook.
ATTENTION: Only qualified electrical personnel familiar with
the construction and operation of this equipment and hazards
involved should install, start and/or adjust this equipment. Read
and understand these instructions in their entirety before
proceeding. Failure to observe this precaution could result in
severe bodily injury or loss of life.
ATTENTION: To avoid a shock hazard, assure that all power to
the drive has been removed before proceeding. In addition, verify
with a voltmeter that no voltage exists at power terminals 181,
182, and 183 before touching any internal parts of the drive.
Failure to observe these precautions could result in severe bodily
injury or loss of life.
Important: If multiple SCRs are being replaced, it is recommended that
you remove and replace one heat sink at a time. This helps to
ensure that parts are properly replaced.
1. Verify that all incoming power is removed to the drive.
2. Remove the drive cover.
Remove the AC Bus Plate
3. For easier access to the AC Bus Plates, remove the Door and Regulator
Assemblies. Label and remove wiring/electrical connections as needed.
Refer to Figure 1.
2
1397 400-600 HP SCR Replacement Procedure
Figure 1
Door Assembly
AC Bus Plates
(1 of 3)
Insulation Plate &
Right Angle Bracket
(6 ea./drive)
Top Phase
M10 x 30
AC Bus Bar
Bolts
Current
Transformer
Connector
M6 x 12 AC
Bus Plate
Bolts
M6 x 12
Insulation
Plate Bolts
Regulator
Assembly
4. Remove the (2) M10 x 30 bolts (22.6 N-m, 200 lb.-In.) that secure the
incoming AC Bus Bar connection. See Figure 1.
5. Remove the (8) M6 x 12 bolts (6.2 N-m, 55 lb.-In.) that secure the AC
Bus Plate to the top heat sink assemblies. Do Not remove the bus bar
from the bus plate.
6. Disconnect the current transformer connector (if working on one of the
two phases with this component).
7. Remove the AC Bus Plate/Bus Bar (and possible current transformer).
8. Remove the (2) M6 x 20 bolts (6.2 N-m, 55 lb.-In.) that secure the
Insulation Plate and Right Angle Bracket below the bus plate.
9. Remove the (2) M6 x 12 bolts (6.2 N-m, 55 lb.-In.) that secure the
Insulation Plate to the heat sink.
Remove the Heat Sink
Remove and replace one heat sink at a time if multiple SCRs are being
replaced. This helps ensure parts are replaced in their proper locations.
1397 400-600 HP SCR Replacement Procedure
3
Figure 2
SCR Clamp
Screws
SCR Locations
for Middle Phase
Additional SCR Locations for
Regenerative Drives
10. Re-insert the (2) M6 x 20 bolts in diagonally opposite holes of the heat
sink to help in the removal and replacement. The bolts will also keep the
side bus bar pieces from sliding out of the heat sink after removal.
Important:A connector is screwed into the heat sink. Use care during
removal to not stress this connector. Use the insulator pieces
previously removed for support. See Figure 3.
Figure 3
Insulation pieces provide
support under the heat sink.
Without support, heat sink
weight would be supported
by the connector, once the
SCR clamp is removed.
4
1397 400-600 HP SCR Replacement Procedure
11. Remove the (2) bolts holding the SCR Clamp (refer to Figure 2) in
place. Remove the SCR Clamp assembly and set it aside.
12. The heat sink can now be removed. Set it aside, and avoid contact with
the machined SCR mating area.
Figure 4
Note the bent pieces on the
top of the heat sink. The M6 x
20 bolts will guard against the
heat sink sliding off of these
pieces.
13. Before removing the SCR, note the orientation of the Anode and
Cathode (outer ring with red wire). Also, note the connections of the
gate lead wires that are attached to the SCR. The replacement SCR must
be installed in the same orientation and with the same gate lead
connections. Refer to Figure 5.
Figure 5
SCR
1397 400-600 HP SCR Replacement Procedure
5
14. Disconnect the leads of the SCR from the tabs on the dV/dt PCB.
Remove the SCR from the drive. Note the captive ring opening for the
gate lead wires of the SCR. Carefully push the SCR out of its captive
ring and set the ring aside. It will be required for the replacement SCR.
Replace the SCR
15. Fit the SCR into the captive ring that was just removed. Verify that the
gate lead wires have sufficient clearance within the captive ring opening
and are not bent or otherwise stressed by the ring.
Figure 6
16. Ensure that the pole faces of the SCR are clean, then apply a thin,
uniform layer of silicone oil (Allen-Bradley #109704, GE SF 1154,
Cerac Special G or equivalent) to each face.
17. Insert the SCR into its proper location. Verify that the cathode outer ring
orientation is correct.
18. Attach the gate leads to the gate lead connectors. The red lead connects
to “K” and the white lead connects to “G.” Route the gate lead wires
such that they do not interfere with the heat sink assemblies.
Replace the Heat Sink
19. Orient the heat sink so that the connector and its mating receptacle on
the dV/dt PCB are aligned. Press the heat sink firmly against the SCR.
Make sure the heat sink is properly supported as shown in Figure 3.
20. Proper assembly of the SCR clamp is shown in Figure 7. Insert the
clamp assembly, ensuring that the spring bars and pressure pad remain
in position. Alternately finger tighten the bolts, so that the clamp spring
bars remains parallel to the heat sink surface.
Figure 7
Insulator Sleeves
Pressure Pad
3 Spring Bars
6
1397 400-600 HP SCR Replacement Procedure
21. Verify planarity using a PIP Gauge (Rockwell #119518 or equivalent).
The gauge should indicate in the “Calibration” region at this point. The
PIP Gauge performs a three point planarity check on the surface of the
SCR clamp top spring bar. When the surface is deflected during clamp
down, the gauge provides an indication of the clamping force exerted.
See Figure 8.
Figure 8
22. Secure the clamp by alternately turning each bolt 1/4 turn clockwise
until the PIP Gauge is aligned with the VE2500 notch. This should
require approximately 2 to 3 full turns of the bolts after they have been
finger tightened.
Regenerative drives have two SCRs under each heat sink piece and two
clamps on each heat sink. Proper bolt tightening sequence must be
performed as shown below.
Figure 9
Tightening Sequence
(Regenerative Drives)
2
3
4
1
1397 400-600 HP SCR Replacement Procedure
7
Replace the AC Bus Plate
23. Secure the AC Bus Plate assembly to the drive with (8) M6 x 12 bolts,
tightened to 6.2 N-m (55 lb.-In.).
24. Reconnect current transformer electrical connection if applicable
25. Secure the Insulation Plate directly to the heat sink with (2) M6 x 12
bolts. Then secure the Right Angle Bracket to the heat sink with (2) M6
x 20 bolts, tightened to 6.2 N-m (55 lb.-In.).
26. Reconnect the AC Bus Bar connection with (2) M10 x 30 bolts,
tightened to 22.6 N-m (200 lb.-In.).
27. Reassemble the Regulator carrier assembly and door assembly to the
drive if previously removed.
28. Reconnect all electrical connections disconnected in previous steps (see
Figure 10).
29. SCR replacement procedure is complete.
Supersedes 1397-SB001B-EN-P – July, 2004
dV/dT PCB 1
THY1
WHT_G4
RED_K4
RED_K3
WHT_G3
THY11
dV/dT Circuit Detail
S6/S6R
0.22 µF
(3) 20 Ohm
(3) 20 Ohm
All dV/dT Circuits Located
on dV/dT PC Boards.
RED_K2
WHT_G2
THY14
281
THY4
WHT_G1
RED_K1
dV/dT PCB 2
RED_K2
WHT_G2
THY16
383
THY6
WHT_G1
RED_K1
WHT_G4
THY2
dV/dT PCB 2
WHT_G4
THY1
dV/dT PCB 1
382
THY5
WHT_G1
RED_K1
dV/dT PCB 3 (Top)
THY3
WHT_G4
RED_K4
THY6
WHT_G1
RED_K1
383
THY3
WHT_G4
RED_K4
RED_K3
WHT_G3
THY13
dV/dT PCB 3 (Top)
S6 Armature Supply
RED_K4
THY2
WHT_G4
RED_K4
RED_K3
WHT_G3
THY12
RED_K4
281
THY4
WHT_G1
RED_K1
RED_K2
WHT_G2
THY15
381
THY5
WHT_G1
RED_K1
S6R Armature Supply
45 (-)
47 (+)
45 (-)
47 (+)
4
11
5
12
6
A
C
A
C
A
C
14
1
15
2
16
A
C
A
C
A
C
45 (-)
3
Top
4
5
6
A
A
A
47 (+)
1
2
3
C
C
C
45 (-)
S6 Thyristor Arrangement
281
382
383
13
47 (+)
281
382
383
Top
S6R Thyristor Arrangement
Anode
Cathode Face Up
Anode Face Up
500 thru 700 HP at 575V AC
400 thru 600 HP at 460V AC
= on dV/dt PC Boards
R = Red
W = White
Cathode
C
A
8
1397 400-600 HP SCR Replacement Procedure
Figure 10
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Publication 1397-SB001C-EN-P – August, 2006
Copyright © 2006 Rockwell Automation, Inc. All rights reserved. Printed in USA.