ML20012B872
| ML20012B872 | |
| Person / Time | |
|---|---|
| Issue date: | 03/05/1990 |
| From: | Alexander S, Potapovs U Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20012B871 | List: |
| References | |
| REF-QA-99901177 99901177-90-01, NUDOCS 9003190077 | |
| Download: ML20012B872 (9) | |
Text
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- 0RGANIZATION: SIEMENS. ENERGY A AUTOMATION /I-T-E CIRCUIT-PROTECTION DIVISION g
y.
TUCKER, GEORGIA y
l' REPORT INSPECTION-INSPECTION NO.:99901177/90 DATE(S): January 17-18,1990 ON-SITE HOURS:
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CORRESPONDENCE ADDRESS:
Siemens Energy & Automation Inc.
I-T-E Circuit Protection Division 3496 Montreal Industrial Way Tucker, Georgia 30084 ORGANIZATIONAL' CONTACT: John P. Halferty, Director Research and Development 404)496-8622
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TELEPHONE NUMBER:
NUCLEAR INDUSTRY ACTIVITY:
Manufacturer of commercial grade molded case circuit breakers and motor control equipment.
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ASSIGNED INSPECTOR:
c Stephen D. Aldxander, Reactive Ins)ection Dath Section-2, Vendor Inspection Branc1, DRIS l
OTHER' INSPECTOR (S):
Randolph r1901g RIS-2, VIB, DRIS APPROVED BY:
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3-or-g Uldis Potapovs, Chief, RIS-2 Date Vendor Inspection Branch Division of Reactor Inspection and Safeguards, NRR L
INSPECTION BASES AND SCOPE:
A.
BASES: 10 CFR Part 21 B.
SCOPE:
To obtain information on: (1) manufacturing and testing of I-T-E molded case circuit breakers (2) Siemens handling of orders for nuclear.
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utilities; (3) Siemens quality control; and (4) breaker tripping on motor starting at the Shearon Harris nuclear plant
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f PLANT SITE APPLICABILITY:
Shearon Harris (50-400) and potentially generic-I 3
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9990117',
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-f ORGANIZATION: LSIEMENS ENERGY & AUTOMATION /I-T-E CIRCUIT PROTECTION DIVISION
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. TUCKER, GEORGIA J
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INSPECTION.
REPORT RESULTS:
PAGE 2'of 9
]t
- NO.: 99901177/90-01' l
A.
VIOLATIONS:-
None'.,
.t B.
NONCONFORMANCES:
None.
C.-
UNRESOLVED ITEMS:
None.
D.
STATUS OF PREVIOUS INSPECTION FINDINGS:
t None.
.E.
OTHER FINDINGS AND COMMENTS:
1.
Background and Purpose of the Inspection
.a.
Background. - Carolina. Power & Light Company's (CP&L's) Shearon-Harris nuclear plagt (SHNP) experienced some test. failures of molded case-circuit breakers (MCCBs) manu-
'480-VAC-rated I-T-E
~ factured by Siemens Energy & Automation, Inc.,.in Wilmington, North Carolina, purchased as commercial grade replacements for
- some older Class 1E (safety-related) 600-VAC-rated MCCBs pursu-anti to NRC Bulletin 88-10. LTesting at the plant resulted in 1
what Siemens claimed were erroneously low magnetic trip current yalues,- but-testing at the. f actory.by Siemens < showed that some of the MCCBs were indeed tripping out of the range indicated in published specifications and time _-current curves.
The MCCBs were also tripping, apparently by their instantaneous magnetic trip function, upon starting of-their AC induction motors loads.
However, the older-MCCBs, which had not experienced premature tripping were found to. trip significantly above the values' on -
.their applicable time-current curves.
Other data.obtained at-f
-Shearon Harris suggested that the problem was peculiar to the 100-amp rated MCCBs with nonadjustable magnetic trips.
I The concern is. that such premature tripping may act to effec-
' tively remove at least one train of safety-related equipment from service when it is called upon to operate during a design basis event (DBE) thus removing one line of defense-in-depth against DBE consequences and - degrading plant safety margin.
'1.
"I-T-E" is a registered trademark of Siemens Energy & Automation, Inc.
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- ORGANIZATION: -SIEMENS ENERGY & AUTOMATION /I-T-E CIRCUIT PROTECTION DIVISION TUCKER, GEORGIA f
3 REPORT-INSDECTION NO : 99901177/90-01 RESULTS:
PAGE 3 of 9
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Purpose. The inspection was conducted to obtain information on.
(1) The history of the manufacturing of I-T-E molded case
' f circuit breakers (MCCBs), (2) the circumstances surrounding the-unsatisf actory performance of the - instantaneous magnetic trip function of commercial grade I-T-E MCCBs at the Shearon Harris nuclear plant, (3) the testing conducted by Siemens on I-T-E i
MCCBs at the Wilmington, North Carolina factory, (4) the commer-cial grade quality assurance program established for manufectur-ing Siemens-ITE MCCBs, (5) Siemens' handling of MCCB' orders for nuclear utilities, (6) electrical performance characteristics of AC induction motors in relation to Siemens-ITE supply MCCBs or -
motor circuit protectors (MCPS) and associated motor controllers during. operation, particularly starting transients, and (7) pub-lished I-T-E MCCB tripping time-current curves of all vintages relative to design and coordination studies, factory testing, manuf acturer's actual expected performance, field testing and customer expectations of performance.
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L 2.
Findings a.
Manufacturing History.
I-T-E MCCBs were manufactured by the j
I-T-E Circuit Breaker Company of Philadelphia until 1966 when l'
the company - was purchased by -Imperial-Eastman and operated as-ITE-Imperia 1'until 1976.
In 1976, I-T-E was sold to Gould Inc.
and operated as ITE-Gould until March of 1983 when Gould sold the I-T-E Division to-Siemens-Allis which became Siemens Energy
& Automation in 1986.
I-T-E MCCBs have been manufactured by l
the. I-T-E Division, now I-T-E Circuit Protection Division, all through these changes in ownership.
The factory was maintained in Philadelphia until 1984, when.
2 under Siemens-Allis ownership, the manuf acturing operation for u
I-T-E MCCBs types "HE" and "EH" was moved to a plant in. Spartan-t burg, South Carolina.
According to Siemens, in retooling for the Spartanburg operation, certain manufacturing process and specification changes were introduced (including apparently relaxation of some tolerances) which resulted in the decision to reduce the voltage rating of these MCCBs from 600 volts to 480-volts.
In addition, factory testing of the initial Spartanburg-made MCCBs indicated that the instantaneous magnetic trip range for the nonadjustable sizes should be raised from a range of 600 to 1000 amps for the 600-volt-rated MCCBs to a range of 1200 to 2000 amps for the 480-volt-rated MCCBs.
However, the' time-cur-rent curves were not revised at that time to reflect the altered performance characteristics.
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- . 0RGANIZATION: SIEMENS ENERGY &-AUTOMATION /I-T-E' CIRCUIT PROTECTION DIVISION i
TUCKER, GEORGIA 1
REPORT.
INSPECTION
- NO.:. 99901177/90 RESULTS:
_PAGE 4 of 9 r
In-1987, under the present ownership, the HE and EH-type I-T-E MCCB manufacturing operation was moved to its present location l
in Wilmington, North Carolina.
The MCCBs manufactured at i
the Wilmington plant retained their 480-volt rating and 1200-2000-amp trip range and new time-current characteristic curves were published.
b.
Circumstances surrounding unsatisf actory I-T-E MCCB performance j
at Shearon Harris:
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NRC Bulletin 88-10 concerning fraudulent / refurbished itCCBs required licensees to verify traceability of MCCBs to their original circuit breaker manufacturers (CBMs).
During the review for traceability at SHNP pursuant to NRC Bulletin 88-10,:
CP&L identified. certain MCCBs that were nontraceable.
- New, 480-volt-rated, Siemens-ITE type HE3B100 MCCBs were or had already been purchased as commercial grade items to replace the nontraceable original ITE-Gould, 600-volt-rated HE3B100 MCCBs used in Class IE (safety-related) loads in the plant such as Reactor Coolant. System Support Fans (S-4) and the Emergency DieselGeneratorRoomFans(E-86). Although, as described above, e
p this line of MCCBs had undergone some changes in.their manufac-L turing process and specifications, CP&L nevertheless procured them on the basis of their being "like-for-like" replacements.
Prior to installation, the ' replacement MCCBs were subjected to L
thermal and magnetic / instantaneous. trip testing at SHNP and were found to trip outside the trip band of the manufacturer's speci-fied band for nonadjustable magnetic trips on HE3B100s of 1200 to 2000 amps.
CP&L then called in a technical representative from the Siemens-ITE factory in Wilmington, North Carolina. The Siemens representative determined that the test equipment and methodology used by CP&L were inadequate to obtain accurate magnetic tripc test results.
Upon retesting ' the MCCBs at the site without modification, but with different methodology under the supervision of the Siemens representative, all the MCCBs reportedly tripped within the specified band and were installed.
However, upon test operation of the MCCBs powering their plant loads, all tripped immediately upon motor starts, apparently by l
' magnetic trip on the inrush transient current.
In an attempt to resolve this discrepancy and to determine why the original 600-volt-rated Gould-ITE MCCBs (also nonadjustable, but with a nominal 600 to 1000-amp magnetic trip band) had not experienced premature tripping in the past, three of the replace-ment, 480-volt-rated, Siemens-ITE MCCBs and one of the original l
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i gy' SIEMENS ENERGY & AUTOMATION /1-T-E CIRCUIT ORGA IZATION:
i
. TUCKER, GEORGIA I
INSPECTION PAGE 5 of 9 REPORT--
RESULTS:
NO :99901177/90-01~
i to the Siemens-ITE 600-volt-rated Gould-ITE MCCBs were sent Under Wilmington factory for further testing and evaluation.
controlled factory test conditions, all three po MCCB tripped below the nominal range, although at measured o
current levels several times those observed during were not able to explain why these MCCBs h SHNP site tests.
at the f actory other than presuming that there were. still some significant error factors in the ITE-supervised site testing.
This issue will require further review with CP&L and the Siemens Wilmington factory.
In response to these findings, Siemens stated their position that at the time when the 480-volt-rated replacement MCCBs were purchased by CP&L as commercial grade' items, undergone factory practice-normally not to perform magnetic calibration tests on Siemens-production MCCBs with nonadjustable magnetic trips.
l stated that the. magnetic trip function of this type of MCCB is verified on a sample basis as a part of certain tests performed under their Underwriters Laboratories (UL)
J in VL Standard 489 and National lines promulgated for MCCBs Electrical Manufacturers Association (NEMA) stan former NEMA MCCB field verification standard AB-2.
The inspector noted as a matter of interest that even if the
' NEMA AB-1 nominal factory testing tolerance of 120% of the tri current setting for adjustable magnetic trips is applied to the nominal nonadjustable band as published in the CBM's time-cur curves, two of the three factory-tested - 480-volt-rated M were still out of tolerance.
and Development stated that he considered that these test res high failure rate for Siemens-ITE indicated an unacceptably commercial grade MCCBs and agreed to-investigate the matt the Wilmington factory.
Siemens' stated that they believed it probable that the origin 600-volt-rated MCCBs had not. been tripping (because they. we actually in a condition as manufactured and not factory-calibrated) to trip at a much higher current level than their nominal range of 600 to 1000 amps as evidenced test results.
the 600-volt MCCBs was tested at the Wilmington factory.
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.4 ORGANIZATION: :SIEAENS ENERGY & AUTOMATION /I-T-E CIRCUIT PROTECTION DIVISIO TUCKER, GEORGIA A
INSPECTION
- REPORT-RESULTS
PAGE 6 of 9.
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..NO.:- 99901177/90-01 The inspectors also discussed with'Siemens some additional test results obtained from SHNP in which some Siemens-ITE HE3B type MCCBs of various other amperage ratings from 40 to 90 amps were reportedly tested with satisfactory results.
However, when another HE3B100 was tested, poles 1 and 2 failed low at 500 y
amps.
This suggested that the problem, if any, may be confined to the 100-amp-rated HE3Bs.
In -response to this information, Siemens stated that, to their knowledge, the magnetic structure n
of all HE3B type breakers rated from 40 to 100 amps is identical.
Siemens also agreed to investigate this issue at the Wilmington 4
factory to determine if there is any reason that the 100-amp HE3Bs should perform consistently differently than the other
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current ratings within the same breaker type.
c.
Testing of I-T-E MCCBs Siemens described the f actory production. test program for 1-T-E f
MCCBs to support continued conformance to UL and NEMA require-3 ments.-
This.was documented, in part, by computer-printed UL '
test program matricos that delineated the UL listing l process tasting program whicn were provided to the inspectors for review.
According to Siemens, the program consists of (1) functional testing of 100% of production breakers (250-350%. thermal calibration, low-middle-high magnetic calibration on adjustable trips, mechanical operation - and ' continuity checks), (2). accep-1; tance quality level (AQL) tests on a variable sample basis, including thermal. calibration at 200.135 and 110% of rated load at 40*C' (to simulate 100% at 25'C),and dielectric withstand at twice rated voltage plus 1000 volts for 1 minute, and (3) "UL followup" testing.
The implementation - of these programs at the factory ~ was not evaluated during this inspection.
Siemens stated that' MCCBs with nonadjustable magnetic trips do not normally receive magnetic calibration.
However, according to a current Siemens policy which has been in effect for about a year, special mag-netic calibration of MCCBs with nonadjur. table magnetic trips is done for special order, commercial grade MCCBs for nuclear plants that request a-certificate of compliance (C0C) in their -
purchase orders.
With respect to field testing of magnetic trips, Siemens stated their position that their published time-current curves are intended to represent nominal design performance characteristics of the applicable MCCBs under actual operating conditions with all poles energized and at the design operating temperature of
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ORGANIZATION: SIEMENS ENERGY & AUTOMATION /1-T-E CIRCUIT PROTECTION DIVISION o
TUCKER,. GEORGIA-
~*
c r.
REPORT INSPECTION-
-NO.:
99901177/90-01 RESULTS:
- PAGE 7 of 9 g
f 40*C installed in a standard motor. control or load ~ center switch-board enclosure.
According to Siemens, they are intended to be used primarily. in conducting _ breaker coordination studies and for characteristic selection in the. design phase of a. given L
installation.
Siemens contended that in~most cases, field test equipment and methods are inadequate to obtain accurate results L
such as theoretically can be obtained under controlled factory test conditions (under which the curves were developed).
- Also, 3iemens pointed out that NEMA AB-1 and 2 do not address nor-L provide test tolerances for testing nonadjustable magnetic trips.
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However,- pending issuance of the new NEMA AB-4 MCCB field' i
verification-standard, which is expected to address magnetic-calibration testing of MCCBs in more detail, including those l
with nonadjustable -magnetic trips, Siemens technical staff L
identified to the NRC inspectors the following recommended field test practices and suggested tolerances on the published time-I current curve values for Siemens-ITE type HE and EH MCCBs:
(1) MCCBs should be mounted on steel backplates or in dumnly l'
enclosures, j
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(2) Connecting test leads should be of the proper size cable
.I and routed away from the vicinity of the magnetic structures which are located near the lower back of the breaker case.
(3) For standardization, poles should be tested singly.
(4) The pulse method should be used with test equipment capable of compensating for current offset or asymmetry and have
-l sufficiently fast response to accurately sense and record -
1 current level at the point of tripping. Trip time measure-i ment capability may also be desired.
l (5) Sufficient time should be allowed between each test for the 1
thermal element (if any) to thoroughly cool in order to j
preclude thermal interaction-influencing the magnetic trip point.
Additionally, the MCCB should be attempted' to be reset immediately after each trip to verify magnetic trip function only.
(6) Siemens suggested that a tolerance of -25% of the low end of the nominal range and +40% of the high end (consistent with the old NEMA AB-2 values for adjustable trips) could a
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ORGANIZATION: SIEMENS ENERGY 8 AUTOMATION /l-T-E CIRCUIT PROTECTION DIVISION
- TUCKER, GEORG1A 4_
}y 1,
REPORT INSPECTION U
NO.: 99901177/90-01 RESULTS:
PAGE 8 of 9 j
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. reasonably be applied to the magnetic trip band on the curves for field testing while adhering to the methods recommended above, d.
Distribution of Siemens I-T-E MCCBs L
(1) Nuclear Safety-Related Material.
No such orders are i
accepted according to Siemens.
Customers were previously referred to Telemecanique, Inc. of Westminster, Maryland, for nuclear safety-related orders and now they are referred to Farwell and Hendricks, Inc., of Milford, Ohio, who pur-chased Telemecanique's nuclear safety-related business.
According to Siemens, all its (2) Commercial Grade Items products are manuf actured and distributed as commercial 3
. grade items as the term is defined for nuclear facilities in 10 CFR Part 21.
(3) Siemens described its distribution network as follows:
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I HE and EH type I-T-E MCCBs are manufactured at the Siemens Wilmington, North Carolina f actory.
Other types of I-T-E MCCBs are made at their Bellefontaine, Ohio plant.
Each plant has a factory warehouse dedicated to its own products.
The warehouse associated with the Bellefontaine, Ohio, plant. is in Columbus, Ohio, and the warehouse for the Wilmington plant is in Norcross, Georgia.
The factory warehouses normally ship stock MCCBs to six regional a
customer service centers according to their stock and special orders.
The custoner service centers then ship to the network of authorized Siemens distributors or direct-1 ship to customers of Siemens sales representatives.
However, when orders are received from nuclear utilities, the distribution network has been instructed not to fill such orders from stock.
Rather* these customers are requested to issue an additional P0 (or change order to the original P0) for traceability documentation and-a C00..
-Such orders, then are referred directly to the appropriate factory warehouse, bypassing all distributors and service centers, from which they are either filled from warehouse stock or the orders are placed on the factory for the breakers to be manufactured.
When the orders are filled, the MCCBs are direct-shipped to the nuclear plant with traceability documentation and the C0C(s).
When the order includes MCCBs with nonadjustable magnetic trip devices,
e.,
ORGANIZATION:.SIEMENS ENERGY & AUTOMATION /I-T-E CIRCulT PROTECTION DIVISION-
~ TUCKER, GEORGIA y
i r
REPORT.
INSPECTION NO.:' 99901177/90-01 RESULTS:
PAGE 9 of.9 s
i these MCCBs get a magnetic calibration at the factory that other such MCCBs do-not normally get and then they are shipped directly to the nuclear plant.
e.
Information was obtained regarding motor. start transients that may be routinely overlooked during the analysis done to deter-r mine the correct replacement MCCB parameters for a given appli-cation.
Specifically Siemens pointed out that the. inrush current transient that occurs within the first cycle af ter AC induction motor starting is a function of locked-rotor current (LRC) and is typically 1.8 to 2.8 times the value of LRC.
- LRC, which nominally varies from 5 to 8 times rated full load current L
(FLC),. although it is functionally unrelated to this parameter, and-which is typically of 0.5 to 2.5 secends duration upon -
starting, may often be confused with the inrush transient which i
is of sufficient amplitude and duration to'cause a magnetic trip L
of the supply MCCB or MCP if its magnetic trip setting is chosen L
based on avoiding only LRC.
Depending on voltage phase angle L
upon closing the starter contacts and the value of the resultant h
asymmetrical current (with offset or DC component), the maximum MCP instantaneous magnetic trip setting )of 1300% of FLC. permit-ted by the National Electric Code (NEC nay be less than the inrush transient peak and thus insufficient on random occasions to prevent unwanted tripping.
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Persons Contacted:
John P. Halferty, Director of Research and Development-u L
Stan Donnell, Senior Industrial Product Specialist Robert Bartheld,' Manager Technology Cooperation Sam Farag, Manager, Motor Control Development Bernie DiMarco, Manager, Product Development-Industrial John Hendricks, President, Farwell & Hendricks Inc. (Siemens consultant)
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