Lightning Protection. Study/Report UMKC Substation. Kansas City, Missouri. Burns & McDonnell. University of Missouri - Kansas City.

Transcription

1 Lightning Prtectin Study/Reprt UMKC Substatin Kansas City, Missuri Burns & McDnnell University f Missuri - Kansas City By: Rbert Biggs

2 The fllwing lightning prtectin study, with its assciated drawings, is intended t display the level f prtectin and suggested lightning prtectin that shuld be added t the new ring bus substatin cnfiguratin in the scpe f the UMKC Substatin Prject. This lightning prtectin study was dne based n the prtectin f equipment in the substatin using different cmbinatins fr the electrdes and shield wires t prvide the best prtectin t the equipment within the substatin frm lightning strkes. All prtectin calculatins have been derived frm the IEEE Standard , "IEEE Guide fr Direct Lightning Strke Shielding f Substatins." UMKC used the rlling sphere methd fr this study. Each calculatin f prtectin was taken as a single piece f prtectin equipment first. Next, depending n the distance f separatin between ther pieces f prtectin equipment the cmbinatin calculatin was dne t determine what level f prtectin exists in between the tw pieces f equipment. Definitins and Equatins: h(e): Referred t as the height f the equipment in feet. This is the tallest piece f equipment needing prtectin arund the electrde. r(c): Referred t as the radius f cnductr in feet. This is the radius r effective radius (in feet) f the energized bus needing prtectin. h(m): Referred t as the height f the shielding mast abve grund in feet. h(w): Referred t as the height f the shield wire abve grund in feet. d(1), d(2), d(3): Refer t the distances between adjacent masts r shield wires (in feet). I(s): Referred t as the strke current. This is the maximum allwable current the statin bus and insulatin can withstand befre experiencing flashver in ka. 2.2xBIL I(s) =! Z( s) fr BIL > 350kV I(s) = 2kA fr BIL 350kV Z(s) = 60Ln(2h(e)/r(c)) S: Referred t as the strike distance. The strike distance is the length f the last stepped leader (in feet), which defines the radius f the rlling sphere. 0.65! S = 26.25kI( s) k is a cefficient t accunt fr different striking distances fr masts and wires. It is 1.2 fr strikes t masts and 1 fr strikes t wires. r: Referred t as the radius f prtectin. The distance (in feet) frm the shielding electrde t the edge f prtectin fr a given equipment height. Fr a Mast:! r = S 2 S h m S 2 S h e fr h(m) < S! r = S 2 S 2 S h e fr h(m) S Fr a Wire

3 ! r = S 2 S h w S 2 S h e r(1): Referred t as the radius (in feet) f the curvature f the unprtected area riginating a distance f x frm the fllwing midpint f tw structures.! r( 1) = S 2 S h e x(1), x(2), x(3): Referred t as the distance (in feet) frm the midpint f adjacent masts (r shield wire supprts), perpendicular t the center f the unprtected area with r(1) as explained abve. Fr a Mast: r =! Fr a Wire: 2 d r = S ( S h( w ) 2! 2 d is the distance between tw adjacent structures (in feet) Calculatins fr Prtectin 138kV Prtectin (See Appendix Figures 1 thrugh ) S 2 2 d 2 2 ( S h( m ) 2 Triple Mast Cnfiguratin 1. Mast1 New lightning mast lcated abve west leg f the new A-frame nrth f the west breaker. Mast2 New lightning mast lcated 84.2' directly nrth f Mast1. Mast3 New lightning mast lcated 71.9' directly east f Mast 1. Prtecting 3 bus whse radius is (See Figure 1) h(e)=25, r(c)=0.1458, h(m)=71, d(1)=68.5, d(2)=84.2, d(3)=113.3 Prtectin Results I(s)=3.45kA, S=70.5, r =16.7, x(1)=61.6, x(2)=56.6, x(3)=42.0, r(1)=53.9, sin alpha=0.60, R=56.9, b=87.7' 2. Mast1 New lightning mast lcated abve west leg f the new A-frame nrth f the west breaker.

4 Mast2 New lightning mast lcated 84.2' directly nrth f Mast1. Mast3 New lightning mast lcated 15.5' nrth and 15.8' east f Mast3. Prtecting 3 bus whse radius is (See Figure 2) h(e)=25, r(c)=0.1458, h(m)=71, d(1)=89.0, d(2)=84.2, d(3)=113.4 Prtectin Results I(s)=3.45kA, S=70.5, r =16.66', x(1)=54.7, x(2)=56.6, x(3)=41.9, r(1)=53.9, sin alpha=0.78, R=57.3, b=87.1 Duble Shield Wire Cnfiguratins 6. First Wire: New shield wire extending frm the 138kV transmissin twer t Mast3 n the east leg f the new A-frame structure. Secnd Wire: New shield wire extending frm Mast5 t Mast6. Prtecting 3 bus whse radius is (See Figure 3) h(e)=25.0, r(c)=0.1458, h(w suth)=80', h(w nrth)=56' d(1)=110.7, d(2)=106.5' Prtectin Results I(s)=3.45kA, S=58.8, r =10.6, x(1)=19.5, x(2)=24.7', r(1)= First Wire: New shield wire extending frm the 138kV transmissin twer t Mast1. Secnd Wire: New shield wire extending frm the 138kV transmissin twer t Mast3. Prtecting 3 bus whse radius is (See Figure 4) h(e)=25.0, r(c)=0.1458', h(w)=56, d(1)=68.54 Prtectin Results I(s)=3.45kA, S=58.8, r =10.6', x(1)=47.7, r(1)= First Wire: New shield wire extending frm Mast1 t Mast2. Secnd Wire: New shield wire extending frm the 69kV transmissin twer t Mast4. Prtecting 3 bus whse radius is (See Figure 5) h(e)=25.0, r(c)=0.1458, h(w masts)=56, h(w twer)=70', d(1)=68.5, d(2)=114.8 Prtectin Results I(s)=3.45kA, S=58.8, r =10.6, x(1)=47.7, x(2)=12.3', r(1)=48.1

5 Recmmendatins The scpe f this lightning prtectin prject includes cmplete prtectin fr substatin cmpnents, in their entirety. UMKC Senir Design Substatin Team recmmends cmpleting this cverage: 1. By running shield wires frm the 138kV transmissin twer t a) lightning Mast1, lcated n the west leg f the A-frame structure, and t b) lightning Mast2 lcated abve the east leg f the A-frame structure. This A-frame structure is lcated between the tw suth breakers and nrth-east breaker. 2. By running a shield wire frm the 69kV transmissin twer t lightning Mast4, lcated abve the west leg f the H-frame structure. The H-frame structure is lcated nrth f the transfrmer and the 69kV breaker. 3. By running shield wire frm lighting Mast5, lcated suth f the cntrl building, t lightning Mast6, lcated nrth f the cntrl building. With these lightning prtectin cmpnents installed in the prescribed lcatins, bth the 138kV system and the 69kV system will have cmplete lightning prtectin cverage. Figure 6 shws cmplete lightning mast and shield wire prtectin.

6 APPENDIX Reference Figures Fr Different Prtectin Cnfiguratins Figure 1 Figure 2

7 Figure 3 Figure 4 Figure 5

8 Figure 6