ML20155H686
| ML20155H686 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco, 05000000 |
| Issue date: | 01/02/1986 |
| From: | Brock N, Irwin J, Whitney D SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | |
| Shared Package | |
| ML20155H523 | List: |
| References | |
| RTR-NUREG-1195 NUDOCS 8605160344 | |
| Download: ML20155H686 (4) | |
Text
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N, ll TROUBLESHOOTING ACTION PLAN ACTION LIST ITEM NUMBER 3A 4
l ACTION LIST DESCRIPTION ICS Eauipnent Investigation i
j QUARANTINED EQUIPMENT LIST ITEM NUMBER e
I RESPONSIBILITY OF Norm Snxi
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PREPARED BY J.N. Inrin dfl. gfM DATE 1/2/86 DESCRIPTION OF ISSUE:
See Attached POTENTIAL ROOT CAUSE(S): Power supply monitor failure.
OUTLINE OF TROUBLESHOOTING PLAN: See Attached 1
j DISCUSSION OF LIKELY CORRECTIVE ACTIONS:
See Attached
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DATE / APPROVED Y A
Kction kist Coordina{or SMUD 1
REVIEWED BY DATE
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DESCRIPTION OF ISSUE:
The purpose of this action plan item is to troubleshoot the operation of the ICS j
r Power Supply Monitor module and understand the circumstances that lead to switches S1 and S2 opening and deenergizing 24VDC to all the ICS cabinets.
A second objective is to record the characteristics of 24VDC power. supply output voltages when total ICS load is suddenly assumed by only 1 of the pairs of power supplies.
OUTLINE OF TROUBLESHOOTING PLAN:
References:
L (1)
Schematic'of ICS power distribution (N21.01-65)
(2)
Electrical Diagram of ICS Power Supply Monitor module (Bailey Instruction Manual E92-81),..
ACTION:
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NOTE:
Documentation of As-Found condition of the i24VDC power supply units and ICS power monitor module IS REQUIRED prior to making any corrective modifications.
i to ICS.
1.
Measure and document the existing low voltage setpoints of,the installed
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power supply monitor module by bench testing using adjustable input voltage l
signals to determi.ne trip setpoints.
2.
Use a recorder to record the operating characteristics of the $24VDC power supplies, re-installed power supply monitor module, and switches S1 and 52 l
when J bus circuit. breaker is opened.
.1 Connect a recorder to the 24VDC power supply bus signals and the ICS power supply monitor module relay contacts which indicate low *24VDC l
bus power.
.2 Verify ICS ABT is in the normal position (aligned to C1 bus and its green lamp is lighted).
1 NOTE:
k The following actions may trip total ICS DC power. Coordinate with Operations.
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.3 With recorder paper speed set, open circuit breaker J4 to initiate j
electrical transient.
s 4 Restore all ICS power and switches to normal after data is recorded.
3.
Determine operating characteristics of repowering.ICS.
.1 With both C and J bus power energized ( and switches S1 and 52 closed) manually turn off i24VDC power supplies PS-1 (X positive) and PS-2 (X negative) (on C bus) and determine if power supplies PS-3 (Y positive) and PS-4 (Y negative) loading will trip open i
switches S1 and S2.
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1 NOTE:
Notify Operations prior to actual tripping S1 and S2.
.2 With Operations concurence open 51 and 52.
.3 With, switches S1 and 52 open (and both C and J busses, energized) manually close S1 and S2 switches to repower the ICS. Monitor and document the behavior of all ICS hand / auto control stations.
4 Verify ICS power supply mcnitor module setpoints insitu.
.1 Connect a recorder to the trip relay contacts of the power supply monitor module and measure and record the power supply output voltages.
CAUTION:
Trip S1 and S2 on total loss of the + 24VDC or -24'VDC bus.
.2 Disconnect the trip signals to switches S1 and S2.
(This step will ensure that the ICS remains energized during this portion of the j
test).
j
.3 Individually decrease the voltage of each power supply unit and document the trip setpoint of the power supply monitor for i
each 124VDC voltages.
4 Vary the power supply units voltages to determine the bus low voltage trip setpoints of the power supply monitor (normally trips S1 and S2).
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.5 Readjust the output voltages of each power supply unit and reconnect the trip signals to switches S1 and 52.
5.
Measure and record the individual trip delay time of 51 and S2.
6.
Using spare modules, investigate the behavior of repowering the ICS H/A control stations.
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j 7.
Remove power supply monitor and install a calibrated spare.
Bench j
test removed power supply monitor, iaw approved Maintenance Instructions.
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DISCUSSION OF LIKELY CORRECTIVE ACTIONS:
1.
If de-en,ergization of either C or J 118VAC busses cause switches S1 and 52 to open, then setpoint changes and/or power supply repair / replacement may
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be necessary.
2.
If ICS control station behavior is found to be neither consistent nor repeatable when the ICS is repowered, then procedures to obtain acceptable control at the hand / auto stations would be developed and submitted for approval.
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