WG3-6-7-15-11-001 IEEE PES SPDC Fall meeting 11/3/15
IEEE PES SPDC Working Group 3.6.7B
Surge Protectors and Protective Circuits Used in Information and Communications Technology (ICT) Networks, including Smart Grid Data Networks
Summary of the October 8, 2015 teleconference on DC feeds to RRH
Chairman: Al Martin, Retired
Vice Chairman: Ernie Gallo, Ericsson
1 Attendance
Members present (5)
Ardley, Tim Adtran
Ashton, Robert ON Semiconductor
Crevenat, Vincent CITEL
Martin, Albert GGG
Maytum, Mick MJMaytum
Members absent (9)
Basciano, Frank Surge Suppression Inc
Drewes, Leonard World Products
Gallo, Ernie Ericsson
Gault, Brad ULLLC
Kobsa, Peter TII Network Technologies, Inc
Oertel, Wolfgang Bourns, Inc
Rebeck, Alan Smiths Power
Travis, Bill Littelfuse
Tran, Thomas Bourns, Inc.
Interested parties present (0)
Attendance: 5 members no interested parties, no visitors, 5 total
Since only 5 of the 14 members were present, there was not a quorum
2 Administration
Meeting Start Time: Thursday October 8, 2015, 8:00 AM Pacific Daylight time
Meeting End Time: Tuesday October 8, 2015, 9:15 AM Pacific Daylight time
3 Review and approval of agenda (-002)
The agenda was approved.
4 IP statement
Slides #1 through #4 of the IEEE Patent Slides updated March 29, 2011 were shown. The WG attendees were advised that:
· The IEEE’s patent policy is consistent with the ANSI patent policy and is described in Clause 6 of the IEEE-SA Standards Board Bylaws;
· Early identification of patent claims which may be essential for the use of standards under development is encouraged;
· There may be Essential Patent Claims of which the IEEE is not aware. Additionally, neither the IEEE, the WG, nor the WG chair can ensure the accuracy or completeness of any assurance or whether any such assurance is, in fact, of a Patent Claim that is essential for the use of the standard under development.
The WG Secretary was instructed to record in the minutes of the relevant WG meeting:
· That the foregoing information was provided and the slides were shown;
· That the chair or designee provided an opportunity for participants to identify patent claim(s)/patent application claim(s) and/or the holder of patent claim(s)/patent application claim(s) that the participant believes may be essential for the use of that standard;
· Any responses that were given, specifically the patent claim(s)/patent application claim(s) and/or the holder of the patent claim(s)/patent application claim(s) that were identified (if any) and by whom.
5 Receipt of contributions
WG3.6.7B-15-10-001 [Al Martin – Unapproved minutes from the 8/18/15 teleconference]
WG3.6.7B-15-10-002 [Al Martin – Agenda]
WG3.6.7B-15-10-003 [Al Martin – Guide Draft 9]
WG3.6.7B-15-10-004 [Mick Maytum – Continuing currents]
6 Review and approval of the notes from the last two meetings [especially actions taken]
The unapproved minutes of the August 18, 2015 were posted August 18, 2015 in the WG3.6.7 private area on the SPDC Website. An E-mail was sent August 18, 2015 to members asking them to review the minutes, and forward any comments to the Chairman. As a quorum was not present, the minutes could not be approved.
The unapproved minutes of the September 21, 2015 were posted September 21, 2015 in the WG3.6.7 private area on the SPDC Website. An E-mail was sent September 21, 2015 to members asking them to review the minutes, and forward any comments to the Chairman. As a quorum was not present, the minutes could not be approved.
7 Review of homework assignments from last meeting:
Al to add figure numbers and titles to the graphs in clause 9. [done]
8 Chair’s Remarks
8.1 Announcement of officers
Chair: Al Martin
Vice-chair: Ernie Gallo
Secretary: Al Martin (acting)
8.2 PAR status
A Project Authorization Request (PAR) for PC62.55 was approved by NesCom at the 2-Sep-2015 NesCom meeting.
9 Old business
9.1 Relevant contributions [in order of discussion]
WG3.6.7B-15-09-003 [Al Martin – Guide Draft 10]
WG3.6.7B-15-10-004 [Mick Maytum – Continuing currents]
9.2 Review the trial draft of the Guide, clause 10.2
Discuss WG3.6.7B-15-10-003 [Al Martin – Guide Draft 10] and
WG3.6.7B-15-10-004 [Mick Maytum – Continuing currents]
Discussed what needs to be done to clause 10.2 in light of Mick’s WG3.6.7B-15-10-004 contribution. The consensus was to replace the existing clause 10.2 with:
CIGRE TB549 estimates that for negative flashes, the arithmetic mean value of the continuing current magnitudes is 321 A. Maximum and minimum values are 1400 A and 22 A, respectively. For positive continuing current the range is 400 A to 35.8 kA.
Figure 4.1 from CIGRE TB549 shows the probability that a given duration of the continuing current occurs (Figure 14):
Figure 14 Probability of occurrence of a continuing current duration (CIGRE TB549)
Now most of the current will flow in the example tower resistance of 2.2 mohms. The voltages developed will be:
Negative
22 A 48.4 mV
321 A 706 mV
1400 A 3.08 V
Positive
400 A 880 mV
35.8 kA 78.8 V
Using the guide example values the continuing current has a negligible contribution to the negative flash SPD energy, because as soon as the impulse energy has gone the sum of the SPD voltages has to be overcome to drive current - 3.08 V won't do that.
The driving voltage for Rwire is IccRtower - Vspdtotal not IccRtower. Further if the 48 Volt feed is trying to reassert itself then the impact of that for specific protection arrangements needs to be considered
Even the highest positive continuing current only generates some 80 V. That plus a possible 60 V from the DC feed is 140 V, and closer to 150 V is likely to be needed to get both SPDs into conduction.
Conclusion: Continuing current is not likely to be a factor for RRH.
9.3 Review the trial draft of the Guide, clause 9
WG3.6.7B-15-09-003 [Al Martin – Guide Draft 10]
Began a discussion of clause 9. As it stands, it lays the ground for clause 10.3.1, which says to assume that an appropriate test is a single surge having the same energy as the sum of the energies of a series of closely-spaced surges.
Ray Hill in an e-mail said that
“I have failed MOV blocks and arresters with one big pulse and by multipulse. Multipulse failure samples had significantly more cracking than a single pulse failure. In addition, failures are within the block and not around the outside. This is consistent with many field failures we’ve seen.
How can one compare multipulse failures which might have a significant period of time between events versus a one-time event? I don’t believe there is a comparison.
During multipulse aging, the knee of the V-I curve drops while the remainder of the curve usually remains the same. During a single shot event, either an arc passes around the MOV block (because at high currents the block cannot protect itself from overvoltage) or the MOV block just overheats and blows up due to a very high current density in one location.
In my opinion, there is no equivalency between the two.”
Taking that comment into account, the WG thought that it might be possible to replicate multisurge failures with a standard 6 kV, 3 kA 8/20 surge repeated at 60 second intervals, if the test was run at elevated temperature.
Vincent said that it is possible to calculate the temperature rise in selected MOVs due to the CIGRE TB549 Table 3.5 median flash of a 5.5/75 30 kA first stroke followed by 5 12 kA 1.1/32 subsequent strokes. Then test the MOVs with standard 8/20 6 kV, 3kA test repeated at 60 second intervals at the calculated temperatures to see when the leakage current increases by more than 50 μA. Vincent took an action item to look into this and report the results.
Tim said he could run a standard 8/20 6 kV, 3kA test repeated at 60 second intervals at elevated temperatures to see when the leakage current increases by more than 50 μA. Tim took an action item to do this, and report the results.
10 New business
None
11 Action Items
Tim to run standard 8/20 6 kV, 3kA test repeated at 60 second intervals at elevated temperatures to see when the leakage current increases by more than 50 μA; and report the results.
Vincent to calculate the temperature rise in selected MOVs due to the CIGRE TB549 median flash of 5.5/75 30 kA first stroke followed by 5 12 kA 1.1/32 subsequent strokes. Then test the MOVs with standard 8/20 6 kV, 3kA test repeated at 60 second intervals at the calculated temperatures to see when the leakage current increases by more than 50 μA; and report the results.
12 Next Meeting
IEEE PES SPDC Fall Meeting
Time: 13:30
Date: Tuesday November 3
Place: Room 2, Coral Reef Ballroom
Marriott Hotel, Delray Beach, Florida
Respectfully submitted
Al Martin, Chairman
October 10, 2015
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