Rockwell Automation 1746-QS,D17466.19 SYNCHRONIZED AXES MODULE - Manual (Page 42)

Wiring Without the Interface Module B–2
Publication 1746-6.19 March 1998
Important: Signals in this type of control system are very susceptible to
radiated electrical noise. Minimize interference from radiated electrical
noise with correct shielding and grounding as follows:
Connect LDT cable shields and drive output cable shields (all shields
at one end, only) to earth ground.
Keep LDT signal cables far from motors or proportional amplifiers.
Connect all of the following to earth ground:
– power supply cable shields (one end, only)
– LDT flange, frame, and machine
– I/O chassis
– AC ground
Use shielded twisted pairs for all connections to inputs and outputs.
Run shielded cables only in low-voltage conduit.
•
Place the SLC-500 processor and I/O chassis in a suitable enclosure.
Important: To minimize the adverse effects of ground loops, you must
isolate power supply and signal commons from earth ground as follows:
6. Connect power supply commons and LDT commons together.
Be sure that they are isolated from earth ground.
7. Connect the cable shield of the servo or proportional amplifier
output cable to a zero potential terminal inside the amplifier.
8. Use bond wires that are equal in size to signal wires.
9. When practical, use one power supply to power only your LDTs.
Repeat this procedure to check out each of the four axis loops.
ATTENTION: Be sure to remove all power to the SLC processor,
LDT, valve and pump beforehand.
1. Disconnect the LDT connector at the head end.
2. Turn ON the power supplies for the LDT and SLC processor, and
check the LDT connector for +15V dc, PS common, and –15V dc.
3. Observe that the module’s fault LED indicates Green.
4. Verify continuity between all of the following commons:
•
shield of the amplifier output cable to the valve
•
output common on
"15V dc PS that powers the LDT
(–) terminal on +24V dc PS that powers the proportional amplifier
•
all LDT commons
5. Verify NO continuity between drive output commons and earth ground.
6. To minimize ground loops, verify that all cable shields are grounded
(at one end, only) to earth ground.
Minimizing Interference
from Radiated Electrical
Noise
Checking Out the
Wiring and Grounding