2010

1. //
/
/
/ Short Circuit and
;oordination Analysis
Glyn J. Lewis, P.E.
Applied Power
Redwood Shores, California
Glyn J Lewis, P.E. Applied Power
2/28/2006
1

2. /
2/28/2006
2
,
HV ahd MV Circuit Breakers
/• AtJSI C37.010
• are nominally rated in MVA.
• by symmetrical interrupting
and withstand. Withstand is
always 1.6 current.
• Use K Factor for lower voltages than breaker
rating.
Glyn J. Lewis, P E Applied Power

3. /
SHORl/CIRCUIT ANALYSIS
,.eclosers and Fault
/ Interrupters
• C37.60
opening asymmetrical current for
closing and withstand.
• X/R ratios vary b' size.
Glyn J. Lewis, P.E. Applied Power
2/28/2006
3

4. //
SHORT/CIRCUIT ANALYSIS
Cutouts
• A'SI C37.40/41/42/44/48
• based upon Symmetrical and
currents.
• Maximum X/R"fatio is 15.
Glyn J. Lewis, PE Applied Powe
2/28/2006
4

5. Mediu Voltage Switches and
Fuses
• ANSI C37.40/46/47
• symmetrical and asymmetrical
amperes.
• Asymmetrical r:atings are 1.6 times
symmetrical ratin'g.
Glyn J. Lewis, PE Applied Power
2/28/2006
5

6. /
Mediu,n; Voltage Conductors
• 240-100
• Fuse protection is limited to 300% ampacity
rating
• Relay pick seth g is limited to 600% of
ampacity rating.
• Size or setting must pmtect cable against F
heating curve.
Glyn J. Lewis, PE. Applied Powe
2/28/2006
6

7. /
/<
• 450-3 and ANSI G57.1 09 for oil filled units
and C57.12.0 for dry type units.
• shown in NEG.
• Verify that primary protection protects against
short circuit with'5tand and combination primary
and secondary proteds against thermal
withstand per ANSI Standards.
Glyn J. Lewis, P.E Applied Powe
2/28/2006
7

8. SHORT ANALYSIS
LOW yOLTAGE SYSTEMS
AND POWER
/CIRCUIT BREAKERS
• C37.13/16/20.1 and UL1558
• is rated in symmetrical amperes with
derate for high X/R ratios over 4.9 for
"fused and 6.6 for unfused breakers. (VI'i;;V
•. "'" 5t. t"tr{"<
• Derate applied to the calculated
symmetrical can be as high as
1.15.
Glyn J. Lewis, P.E. Applied Power
2/28/2006
8

9. CIRCUIT ANALYSIS
PANELBOARDS,
AND INSULATED CASE
< BREAKERS
• EqbJipment rated in symmetrical amperes
with"d€rates for high X/R ratios.
• applied to the breaker rating
and can be"as low as 0.62 for X/R ratios
above 20. Ca;eful consideration must be
given to where the
X/R ratios are high.
Glyn J Lewis, P.E. Applied Powe
2/28/2006
9

10. ANALYSIS
SWITCtlBOARDS, PANELBOARDS,
MOL ED AND INSULATED CASE
BREAKERS
• Ttieze are serious limitations per UL489
case and insulated case
applied on ungrounded,
delta and high resistance
grounded systems.
Glyn J Lewis, P.E. Applied Powe
2/28/2006
10

11. LOW VOLTAGE SERIES RATINGS
• Equipment can be rated with a line side
device. That is, a breaker of
higher"i, terrupting capacity or a fuse.
UL67 or NEG 110.22;
• Series tested com'tJlnations as listed i
the UL "Yellow BOOK' only apply.
Glyn J. Lewis, PE. Applied Powe
2/28/2006
11

12. LOW' OLTAGE CONDUCTORS
• Use"ampacities from NEe Table 310-16 and
• Use 60 degree column for less than 125A.
• Use 75 for 125A and over.
• Up to 800A use trip equal or up.
• Over 800A use equal OF next size trip down.
Glyn J. Lewis, P.E. Applied Power
2/28/2006
12

13. /// LV FUSE
2128/2006
Glyn J. Lewis, P.E. Applied Power 13

14. 2/28/2006
14
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15. / FUSE - FUSE
COORDINATION
2/28/2006
Glyn J Lewis, P.E. Applied Powe 15

16. 2/28/2006
16
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17. /
/ FUSE-BREAKER
COORDINATION
/
2/28/2006
Glyn J. Lewis, PE Applied Power 17

18. 2/28/2006
18
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19. MOLDED CASE BREAKER
2/28/2006
Glyn J. Lewis, P.E Applied Power 19

20. 2/28/2006
20
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21. //MOLDED CASE -
( MOLDED CASE
COORDINATION
2/28/2006
Glyn J Lewis, P.E. Applied Powe 21

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2/28/2006
22

23. /
/
///POWER CIRCUIT
BREAKER
2/28/2006
Glyn J. Lewis, P.E. Applied Power 23

24. 2/28/2006
24PAGE 12C OF
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25. /MEDIUM VOLTAGE
FUSE
(),HARACTERISTICS
2/28/2006
Glyn J. Lewis, P.E. Applied Power 25

26. 2/28/2006
26
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FUSEs
•
S0pRCB ISIDE "K";t.ND 'T" LI II:
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or;
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27. /
/
COORDINATION
2/28/2006
Glyn J. Lewis, PE Applied Power 27

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2/28/2006
28

29. /
COORDINATION
2/28/2006
Glyn J. Lewis, PE. Applied Power 29

30. 1'1C;2 5C OF 2.IlC
2/28/2006
30
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31. 2/28/2006
Glyn J. Lewis, P.E. Applied Power 31
//
/
COORDINATION
SOLID STATE

32. 2/28/2006
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PROVIDE --
SEfECTivE TRrPPIN
1·
CLOSER D THAN
DUE TO

33. /
/
/
/
// RELAY-FUSE
COORDINATION
2/28/2006
Glyn J. Lewis, PE Applied Power 33

34. 2/28/2006
34i'lI.OE 01' 20t'
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• • • • •• • • • •• • •
SC"'-E, I.- 1

35. 2/28/2006
Glyn J. Lewis, P.E. Applied Powe 35
/
/
/
/.v GROUND RELAY
COORDINATION

36. 2/28/2006
36
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/

37. /
DESIGNING
/ FOR
/ COORDINATION
AND
SEL "CTIVE TRIPPING
2/28/2006
Glyn J. Lewis, PE. Applied Power 37

38. 2/28/2006
38
TT
LACK OF SELECTIVE TRIPPING
WITH G. F. RELAv
//
.7ADD
• I ,r-••----I
v "
1 (
T
c:;
./
« 'j

39. 50 DEVICE TO BE
SET AT 1, 6 SYM
SECONDARY FAULT
CURRENT
MR t:-O-O50/51 50/5! N
T
50/51 50/51 N
MRJ::-o-o
f 50/51 50151N
¢
MR
/
/
/
LACK OF SELECTIVE TRIPPING
DUE TO INSTANTANEOUS ELEMENTS
V
I
MR ::-0-0
50/51 50/51N
T

40. ¢
k
¢
J---OMR MR
51 51N 51 SIN 51 51N
DELETE INSTANTANEOUS TRIPS (IT)
(IF POSSIBLD
UTILITY MAY FORCE USE OF IT'S
Glyn J. Lewis, PEApplied
t:;j" SIN
¢
T T
LILU/LUUU
40

41. • 51 SIN
MR MR MR
50/51 SO/SiN
T
50/51 SOISIN
T
50/51 SOISIN
T
ADD DIFFERENTIAL PROTECTION
(UTILITIES WTLL ACCEPT THIS TN LIEU OF IT ON MAIN)

42. /MAIN) LSG
t
DB
FEEDER) LSIG
TMAIN) LSG
__lI M_S-'-B
LSIG
tFEEDER) LSG
1
...... ':1" ............... ,.... , ' ...... , .t-' ..... " ......... , ............ ' VWHAT ARE THE LI MIT AT TONS OF TH I S SYSTEM? 006
42

43. '06
ZONE INTERLOCKING TO RESOLVE COORDINATION43
V
/
/
TMAIN ) LSG 0.3 SECS 0,3 SECS
r nnn-----<1: -§nn-t>
r
r TIE
: MSB f:-{---'»>-_ _
I
I 1-----------
I I tI I
g 2 _SECS
l
r
IZ:31 0,2 SECS
r
-.J
MAIN )/LSG
DB t
FEEDER }:SlG n_n __@0 1 SECS

44. t t t)LS(]) )LS(]) )LS(])
_1 1 1-
ALL GENERATORS THE SAME SIZE,
WHICH BREAKER TRIPS FOR A GENERATOR
ALL BREAKERS ARE SET THE SAME,
Glyn J. Lewis, PE Applied powerV
/
12006
44
FAUL 17
)
G3
)
G2
/
)
Gl

45. ADD HS GENERATOR DIFFERENTIAL TO
PROVIDE SELECTIVE TRIPPING,
DELETE IT OR SET HIGHER THAN ASYMMETRICAL
FAULT CURRENT FROM ONE GENERATOR,
Glyn J. Lewis, P.E. Applied
i"'U'I (
87G
y)
,
I
) LS( [)
1
(
87G
G2
/"
87G
t) LS( ])
1
G3
)
t) LS( I)
1v
(
2/28/2006
45
/