grounding and grounding fault analysis

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Grounding Grounding FaultAnalysisHow to calculate Grounding FaultHow to understand Grounding Fault

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  • ( 3 )

    /

    2013. 12

    www.p7c.co.kr

  • - 2 -

    -ANSI/IEEE Std. 141-1986[page 172, 347]

    -ANSI/IEEE Std. 141-1986[page 255~258]

    -ANSI/IEEE Std. 141-1986[page 286]

    -IEEE Std. 142-1991[page 20]

    -ANSI/IEEE Std. 242-2001[page 238~239]

    - IEC / , [2009]

    - [2] / , [2003]-

  • - 3 -

    Profile

    1. - 56 ( 4 1984)- (1984~1992) - (1992~1996) -( ) (1996~2003) - , (~2012) - (2004~ )

    2. - (1998) - ( 14-06-003 )

    3. - [1] (2003) - [2] (2003)- - [3] (2010) - ! (2013)

    4. : www.p7c.co.kr

  • - 4 -

    1. 2. 3.

    /

    GPT

    4. RN NGR(Neutral ground resistor) 3 GTR(Grounding transformer)

    5. 1

    6. 7. Next to : 4

  • - 5 -

    3

    1.[ 1]

    2

    1 : 380mA ~ A : ~ A ( )

    : 5~10A / : A(IR 3IC0 )

    A ( 3 )

    1

    ( E0) ( arc 6~8 )

    ( E0) ( 2.6 )

    (1.4E0) [ ] 2.

    - - -

    (GPT, ZCT, SGR )

    .

    [ ] 1. (E0 ) (E0 ) . 2. 1000V IEC 60364 [ 4] .

    3. arc . ( ) 4. -> ->

  • - 6 -

    3

    2. ( )

    [ 1] (ANSI/IEEE Std 141-1986[172] Fig 47)

    [ 2] [ 3]

  • - 7 -

    3

    3.

    [ 4]

  • - 8 -

    3

    3.

    / 1IC1 = IC2 = IC3 = 2fcE

    , E = V3

    : (3 ICg = IC1 + IC2 + IC3 = 0A)

    C : 1 ( / )

    a , a [ 4] 3

    I

    C2 = I

    C3 = 2fc3 V

    3= 2fcV

    , jIC?jIC =I C2+I C3 =

    3 2fcV =3 2fcE ( A )

    GPT

    IGF = (IN+ jIC )tan 1 ICIN (A ) (GPTIN 380 GPT .

    70~90 , .)

  • - 9 -

    3

    3.

    [ 2] 6.6kV

    -

    -

    PM1

    PM1 9.12A 87.6 -PM1 5.55A 82.1 -

    0.83 62.92 -PM1 MAIN 15.48A 82.9 -

    PM3

    PM3 10.3A 87.8 12.91A 88.3PM3 6.71A 86.7 9.32A 87.6

    6.56 86.6 -PM3 MAIN 23.6A 86.3 31.44A 87.2

    [ ] 1. , 2. .

  • - 10 -

    3

    3.

    , a ?

    Vb =(a 2 1 )Z0 + (a 2 a )Z2

    Z0 + Z1 + Z2Ea

    VC =(a 1 )Z0 + (a a 2 )Z2

    Z0 + Z1 + Z2Ea

    , : 1 = 10 = 1 + j0 , a = 1120 = 12 + j3

    2, a 2 = 1240 = 12 j

    3

    2, 1 + a + a 2 = 0

    : : : :

    [ 5] [ 6] , : [ 5] , , , , : [ 6] ,

  • - 11 -

    3

    3.

    [ 6] , Z0 = XCO = 1wC 0 ,

    + 3 .

    Z 0 + Z 1 + Z 2 0 , (-2) .

    [ 7] [ 7] , . , 1

    6~8 , . .

  • - 12 -

    3

    3.

    , 6~8 . Surge .

    GPT

    / .

    6~8 . Capacitance Capacitance Inductance , .

    If this ground fault is intermittent or allowed to continue, the ungrounded system could be subjected to possible severeover-voltages to ground, which can be as high as six or eight times phase voltage. Such overvoltages can puncture insulation andresult in additional ground faults. These over-voltages are caused by repetitive charging of the system capacitance or by resonancebetween the system capacitance and the inductances of equipment in the system. [ : ANSI/IEEE Std. 242-2001 8 page238~239]

  • - 13 -

    3

    3.

    GPT

    [ 8] GPT [ 9]

    2011.6.22 : 6.6kV 190kW , SGR -> GPT 3

  • - 14 -

    3

    4.

    [ 10]

  • - 15 -

    3

    4.

    RN

    3 , RN . -Y , - .

    , [ 11] IR = IN 3IC0 .

    [ 11]

  • - 16 -

    3

    4.

    NGR(Neutral ground resistor)

    : NGR , IN 3IC0 : IEEE 32 10 , 1 , 10 , 30 .

    : 13

    .

    : 10 , 1 760 , 560

    ( )

    R N =EIN

    =6600V/

    3

    200A= 19,

    , 6.6kV/3 , 200A, 19 , 30 , ( 200A )

    [ ] , .

  • - 17 -

    3

    4.

    3 GTR(Grounding transformer)

    Ground Transformer 3kVA = 3 (V /

    3 )

    Ig3

    k3

    , V : (kV), Ig : (A), k 3 : (%)

    [ 3] k3 factor 3 Y- k3 factor

    10 -1 0.1702 0.2403 0.2954 0.3405 0.380

    [ ] IEC 1 95 / 3

    : Q = 6, 6003

    200 0 .240 = 183 [kVA ] 200250 [kVA ] , ( 200A )

    : Pri. 6.6kV/3 (Wye connection with / neutral terminal ), Sec. 380V (Delta connection ) %ZPS =5.58% .

  • - 18 -

    3

    5.

    [ 12]

    , , 1 - , -

  • - 19 -

    3

    5.

    [ 4]

    TT TN-C TN-S IT

    IT

    (N) 1.45Uo - 1.45Uo 1.45Uo -

    (PE) 3Uo - 1.45Uo 3Uo 3Uo

    PEN - 1.45Uo - - -

    [ 1] Uo ( )

    [ ] 2 (SPD)

  • - 20 -

    3

    5.

    1

    [ 5] 1

    TT TN-C TN-S IT Ungrounded

    1. (In) TN A A 10A GPT 1380

    2. (IC) 1A 1A 1A 1A 1A

    [ ] 1. IC 1A , .ANSI/IEEE Std 141-1986[172, 347]

    2. IT 10A . IEEE Std 142-1991[20] 3. Z0 < Z1 or Z2 , 1 3 125% .ANSI/IEEE Std 141-1986[286] 4. (Zero Sequence Current Transformer) ( : 480V 1000/5A ) ANSI/IEEE Std 141-1986[255~258]

    [ ] (Equipotential bonding) , , 1 3 , (7. )

    Ig = 3I0 =3E

    Z 0 + Z 1 + Z2 + 3Rf Ig = 3 100%Z0 + %Z1 + %Z2 + 3Rf

    IN ISC = 100%Z1IN IN : , 3Rf : 0

  • - 21 -

    3

    5.

    [ 13] 440V

    VCB

    ACB

    MCCB

    . . . . . . . . . . . . . .

    Inverter

    M150kW

    160kW*

    M112kW

    DCM

    112kW

    DC

    22.9kV

    440V

    M110kW

    160kW*

    M200kW

    220kW*

    440V

    440V

    * .

    Inverter Inverter

    Converter 170kVA

    MCCB MCCB MCCB

    Converter 170kVA

    MCCB

    MCCB MCCB

    MCCB MCCB MCCB MCCB

    . . . . . . . . . . . . . .

  • - 22 -

    3

    5.

    [ 6]

    22.9kV/440-254V3 1800kVA

    %Z=4.64,

    SV2200IP5A-4OL440V, 220kW

    2012.04.30~07.23

    3

    2012.07.24

    2012.07.24~08.11 2012.08.11

    2012.08.27~08.31 2012.08.31 TR ACB

    2012.09.14~09.14 2012.09.14 1600rpm

    SV1600IP5A-4OL440V, 160kW

    2012.07.24~08.24

    22012.08.31 2012.08.31 TR ACB

    2012.09.14 2012.09.14

  • - 23 -

    3

    : 3 Y , [ 14] 3 . .

    [ 14] 3 94.22V ( ) [ 15] 3 0.19V ( )

  • - 24 -

    3

    : 3 Y , N~M point 94.22V , over lap . -> 3 4 ,.

    [ 16] 3 [ 17] 3 N~M point

    [ ] 3 6 1, 3, 5 4, 6, 2 120 , 1~4, 3~6, 5~2 . 1, 3 (Over lap) AC . AC .

  • - 25 -

    3

    6.

    [ 18]

    1

  • - 26 -

    3

    6.

    [ 19] ( )

    [ 20] (Ring Core Balance)

    [ 21] 3

  • - 27 -

    3

    6.

    [ 22] GPT [ 23]

    R = n2 r9

    = 302 509

    = 5, 000 ( ) R : 1 , n : GPT , r :

    GPT 3 (0.38A/3 ) 30 = 3.8A GPT 3.8A 190V = 1902/50 = 722VA (CLR) (3.8A )2 50 = 722W, . [ ] 440V .

    ZCT 200/1.5mA : n0-, n0>100, n0>2000 ( 20A n0>100 )

  • - 28 -

    3

    7.

    [ 24]

    25SGR CLR

    200/1 .5m A SGR SGR

    M

    CLR

    6.6kV BUS

    6.6kV BUS

    200/5A OCGR

    M

    6.6kV BUS

    6.6kV BU S

    NG R19.05200A

    OCGR OCGR

    G PT 500VA x 3

    200/5A 200/5A200/1 .5m A

    200/1.5m A

    200/5A

    380m A

    380m A

    ( )

    25

    G PT 500VA x 3

    G TR250kVA

    OCGR

  • - 29 -

    3

    2 100/5A

    [ 25] 2

  • - 30 -

    3

    7.

    . 100/5A 1,000/5A , 2 . 1 : Ig = 3I0 = 3 100%Z0 + %Z 1 + %Z2 + 3Rf IN ISC =

    100%Z1

    IN =1006

    2000 kVA3 0.38

    50kA

    : 1.0VA ( ) : 5P 10P (KSC IEC 60044-1 )

    . (50,000A/100A)=500 (50,000A/1,000A)=50 , 1.0VA ? 1.0VA ?

    1.0VA500=500[VA] . 1.0VA50=50[VA] . = = 20 ? 10 ?

    500/20=25[VA] . 50/10=5[VA] .

    . 2100/5A, 25VA, 10P20, 63kA 1,000/5A, 5VA, 5P10, 63kA

    MCCB Trip Tap Range 0.5~2.0A Tap Range 0.5~2.0A

    2.0A 1005

    = 40 (A ) pick up 2.0A 1,0005

    = 400 (A ) pick up

  • - 31 -

    3

    , 4

    .

    .

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