Siemens 3PCI Series, Operation Manual

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3PCI SCR Power Controller Series Manual Troubleshooting
Version 1.2 (19000325)
s
5-3
provide more cooling, or the 3PCI should be moved to a cooler location, or call the ROBICON service
department.
5.4.4. Excessive Vibration
A significant degree of pitched or unpitched vibration can cause numerous problems. If vibration is isolated as
a probable cause of improper operation, standard vibration-isolation mounting techniques should be
employed.
5.5. Input Power and Load Connections
Turn off the power to the 3PCI and check all power connections, input and output, to make sure they are
mechanically secure and free of corrosion. Make the same checks at the power source and load. Visually
check insulation on input and load wiring for evidence of damage or overheating.
5.6. Correcting Specific 3PCI Problems
Table 5-1 provides a comprehensive guide for troubleshooting the 3PCI. Refer to this table for possible
causes and solutions.
Table 5-1. 3PCI Troubleshooting Symptoms and Solutions
Symptom Possible Cause(s) Possible Solution(s)
1. No output–
even with manual
control (BIAS)
turned full CW. (a) System has an
open SCR fuse.
(b) SCRs are not
firing.
(a) Remove and check the fuse. If it
has opened, replace it after
completing (b).
(b) Install a good fuse in the circuit, and
apply power to the 3PCI. If the
output is fully controllable using the
manual control, then resume normal
operation. If the power output is still
zero, contact ROBICON service.
2. Output is
variable, but
cannot be
brought to zero
with bias control. (a) SCR network
shorted.
(b) Firing control
section
defective.
(a) Check SCR network per solution
listed below in solution 4(a).
(b) Contact ROBICON service for
assistance.
3. Output is
variable, but
cannot be
brought to
maximum with
GAIN control. (a) Firing control
section
defective.
(a) Contact ROBICON service for
assistance.
4. Maximum
power at all times
regardless of the
control setting. (a) All SCR
networks are
shorted.
(b) Firing control
section
defective.
(a) On units rated above 225 A:
Remove the fuse and check the
front-to-back SCR pairs by
measuring resistance between the
cathode of the SCR being checked
and an unanodized portion of the
heat sink. On the R
×
1 scale, the
resistance should be infinite in both
directions. If a shorted component
is indicated in any of these checks,