Minutes of the Dry Type Reactor W

MINUTES OF THE DRY TYPE REACTOR W.G.;

ORLANDO, OCTOBER 15, 2001

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The Dry Type Reactor W.G. met Monday, October 15, 2001 in Salon 2 of the Rosen Centre Hotel in Orlando Florida. Four members and three guests attended.

MEETING HIGHLIGHTS

1)  The attendance list was circulated.

2)  The minutes of the last meeting, April 10, 2001 in Amsterdam were approved.

3)  Reaffirmation status of C57.16 and C57.21 was reviewed.

Accredited Standards Committee C57 (ANSI) ballot of C57.16 failed June 12, 2001 due to lack of ballot response. ANSI requires at least 51% of eligible voter response. C57.16 ballot return was only 40%. All returned votes were affirmative.

As the IEEE reaffirmation ballot (which closed on April 6, 2001) was successful the standard is considered reaffirmed and will be published early next year. The ANSI ballot failure and resolution is scheduled to be discussed at the ASC C57 Main Committee meeting Thursday, Oct. 18, 2001.

Reaffirmation of C57.21 was delayed due to errors introduced into the document by the scanning optical character recognition program used by IEEE. The editing process is now underway and the reaffirmation ballot should be ready in approximately two weeks.

4)  The second draft of an annex for C57.21 concerning Thyristor Controlled Reactors was reviewed. The following modifications were recommended and will be incorporated in Draft #3 of this annex. It was agreed that Draft #3 would be issued to all W.G. members in a "Final Draft" with the meeting minutes.

(i) A.2.3: Include definition of "RSS" as root sum squared where "RSS" is first stated, or in definition section.

(ii) A.3.2: Include statement that although di/dt can be limited by just one single reactor of a reactor pair this is not quite as effective as a two coil approach due to ground capacitance effects.

(iii)  A.3.4: Confirmation to be obtained regarding acceptability of reference to an IEC standard in an IEEE standard.

(iv)  A.4.6: Change "should" to "shall".

(v)  A.4.7: Remove 75°C as option for reference temperature. Use 20°C plus the average temperature rise of the reactor.

(vi)  A.5.1(d): Copies of a typical turn to turn test oscillogram were distributed. The rise time of the first peak was on the order of 0.1 microsec for dry type reactors. Therefore the "note" will be removed.

(vii)  A.5.4.3: Change the second to last paragraph to read, "The measurement of the losses shall be performed after dielectric testing and if so specified, also be performed prior to the dielectric test."

(viii)  A.5.4.4: Change the first sentence of the note to read, "The lightning impulse test is generally not required on thyristor controlled shunt reactors unless specifically requested by the end user, since they operate at distribution voltage class levels.

(ix)  A.5.5.1: Add comment to describe "structure elements".

Also add the following sentence to the second last paragraph, "if such connector and incoming bus are not supplied, the terminal temperature rise cannot be assessed.

(x)  A.5.6.1.1: Add statement that sound levels measured in the laboratory may be different from those measured at site due to actual simultaneous application of harmonics in service at site.

(xi)  A.5.6.1.2 to A5.6.1.8: All information that has been already stated in the main section of the standard will be deleted.

(xii)  A.6.2: The statement regarding losses that appears in C57.16 will be used. Two loss figures may be stated one for upper and one for lower unit of stacked reactors, where applicable.

(xiii)  A.7.1: Altitude will be made optional information on the nameplate. System voltage will be made recommended information on the nameplate.

(xiv)  A.7.2: System voltage removed. Harmonic current spectrum included.

5.  The first draft of Annex B for C57.21 concerning shunt reactor switching was reviewed. The following modifications were recommended and will be incorporated in Draft #2 of this annex to be issued to all W.G. members with the meeting minutes:

(i)  B.1: First paragraph - "SWIL" will be corrected to read "SIWL". The last sentence will be deleted. A sentence will be added stating that a chopped wave test could be considered to simulate a switching device reignition phenomenon. Second paragraph - the last sentence will be deleted.

(ii)  All: "Shunt reactor switching device" will be used instead of "circuit breaker".

(iii)  B.3.1: Second paragraph to be changed to read, "chopping number (l) is circuit breaker dependent. Severity of chopping is described by a chopping current which is a function of chopping number and the total capacitance seen by the circuit breaker; stray capacitance of the shunt reactor plus the parallel capacitance across the circuit breaker contacts. Typical chopping numbers are:

Air blast circuit breakers: 15-25 x 104 A.F. -0.5

SF6 circuit breakers: 4-17 x 104 A.F.-0.5

Minimum oil circuit breakers: 7-10 x 104 A.F.-0.5

I Chopped = l

Second last paragraph: start first sentence with, "For extra high voltage (>362 kV) ………

Last paragraph: (<362 kV) to be changed to (£ 362 kV).

(iv)  B.3.2: In second last sentence of the first paragraph, parenthesis to be closed.

Last paragraph on Page 5 of 8 to be deleted as it is repeated directly above.

(v)  B.3.2: Page 6 of 8, table title to be changed to "Typical Worst Case Dielectric Stresses on Shunt Reactors During Re-Ignitions".

Another method other than colour coding to be used to identify cases where dv/dt is a concern.

(vi)  B.5.0: First sentence to be deleted and replaced with, "Surge arresters shall be used to protect shunt reactors".

The following sentence is to be added to the second paragraph, "The switching device should be qualified for switching reactors and its characteristics should be known in order to evaluate reactor overvoltage stresses caused by switching.

(vii)  B.6.0: Heading to be changed to read "maximum switching transient overvoltage."

Delete the first sentence of the first paragraph and replace with, "The following are maximum overvoltage levels that shall not be exceeded unless agreed upon by the user and manufacturer."

Replace the last three words of the last sentence of the first paragraph with, "has been considered."

(viii) B.3.1: The following statement to be added below the chopping numbers, "Vacuum circuit breakers are commonly used to switch shunt reactors connected at distribution voltage class levels." Chopping numbers for these breakers are not available.

Two other requests for change that were not adopted were as follows.

(i)  B.3.1: Air blast and min. oil breakers are not being used for new installations and hence chopping numbers for these are no longer relevant.

The values were retained in the text since some utilities use older in stock breakers for new installations.

(ii)  B.6.0.1: SIWL for solid insulation, bushings for example is only approximately 70% of rated BIL, not 83% of BIL as proposed.

Consensus at the meeting was to retain the 83% figure for simplicity and since other factors for "aging" and "margin" were also included.

No further discussion or new business was raised. The meeting adjourned at approximately 11:50 a.m.

Mike Sharp

MS:jl

(99225)

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