Student Resource Building
University of California Santa Barbara
Clement Fung
Lighting | Electrical Option
APPENDIX E
Electrical System Single Line Diagram
Overcurrent Protection Study
Overcurrent Protection Device Specifications
2400
3600
4800
6000
7200
9600
200
300
400
500
600
800
4
7
12
18
35
75
10000
Time(s)
10000
150
40
18
10
7
0.03
400
800
1200
1600
2000
2400
3200
100
800
600
500
400
300
200
Time(s)
Actual Current (A)
% of Rated Current
400
Transformer T1A (primary)
1200
100
Breaker Rating (A)
Actual Current (A)
1200
Main Switchboard (MS)
% of Rated Current
Breaker Rating (A)
Overcurrent Protection and Coordination
0.9
2
3.5
6
15
70
10000
Time(s)
345
690
1035
1380
1725
2070
2760
Actual Current (A)
800
10000
70
30
17
10
6
0.04
Time(s)
Transformer T1A (secondary)
400
300
250
200
150
100
50
Actual Current (A)
50
Panel H3Aa
0.7
150
300
450
600
750
900
1200
Actual Current (A)
150
2
3
5
10
45
10000
Time(s)
10000
120
40
20
9.5
5.2
0.04
Time(s)
Feeder to Panel L1Aa
480
360
300
240
180
120
60
Actual Current (A)
60
Panel H2A
800
600
500
400
300
200
100
Actual Current (A)
100
Panel H1A
0.035
0.8
2
4.5
12
40
10000
Time(s)
1600
1200
1000
800
600
400
200
Actual Current (A)
200
Feeder to H1A
1.5
2.5
4
6
17
45
10000
Time(s)
Time (Seconds)
0.01
0.1
1
10
100
1000
10000
10
100
Current (A)
1000
Time-Current Curves For Branch Circuit Protection
"Path B-C-D-E"
10000
1200A
100A
200A
60A
50A
Time (Seconds)
0.01
0.1
1
10
100
1000
10000
10
100
Current (A)
1000
Time-Current Curves For Branch Circuit Protection
"Path B-1-2"
10000
1200A
400A
800A
150A
Application Data
29-167N
Page 3
AB DE-ION Circuit Breakers
Types ND, CND, HND, CHND, NDC, CNDC Equipped With Type NES Digitrip RMS 310 Trip
Units With Adjustable Short Time Delay (Phase Protection)
CURRENT IN MULTIPLES OF RATING PLUG AMPERES (In)
.5 .6 .7 .8 .9 1
2
3
4 5 6 7 8 9 10
20
1 HOUR
2 HOURS
10,000
Circuit Breaker Time/Current Curves (Phase Current)
Series C® N-Frame Circuit Breakers
Equipped With Type NES Digitrip RMS 310 Trip Units
The NES Digitrip RMS 310 Trip Units are AC only devices that employ microprocessor
based technology that provides true RMS current sensing means for proper correlation
with thermal characteristics of conductors and equipment. They are used with Circuit
Breaker Types ND, CND, HND, CHND, NDC, and CNDC.
5,000
3,000
Adjustable Short Time Delay
Typical Trip Unit Nameplate
Digitrip RMS 310 Rating Plug
2,000
Push
to
Trip
Standard Fixed
Rating Plug
Short Delay
Pickup
x In 5
4
6
Cat.–
/n–
“Y”
3
Engaged
Digitrip RMS 310
Trip Unit
40°C Ambient
7
2
8
TEST
Remove
1,000
Frame
Rating
Amperes
(Max.)
500
800
300
200
1 MINUTE
100
Long Delay➀
Maximum Total
Clearing Time
1200
Long Delay➀
Minimum Total
Clearing Time
50
Available Rating Plugs
Ampere
Type
Rating (I n )
Catalog
Number
Short Delay
Pickup Range
Amperes
800
700
630
600
550
500
450
400
400, 500, 600, 800
400, 500, 630, 800
1200
1000
900
800
700
630
600
600, 800, 1000, 1200
8NES800T
8NES700T
8NES630T➃
8NES600T
8NES550T
8NES500T
8NES450T
8NES400T
A8NES800T1
A8NES800T2➃
12NES1200T
12NES1000T
12NES900T➃
12NES800T
12NES700T
12NES630T➃
12NES600T
A12NES1200T1
1600-6400
1400-5600
1260-5040
1200-4800
1100-4400
1000-4000
900-3600
800-3200
800-6400
800-6400
2400-9600
2000-8000
1800-7200
1600-6400
1400-5600
1260-5040
1200-4800
1200-9600
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Adj.
Adj.
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Adj.
Interrupting Ratings – 50/60 Hz
RMS Sym. Amperes (kA)
UL/CSA
Breaker
Type
240V
480V
65
50
ND, CND
100
65
HND, CHND
200
100
NDC, CNDC
30
2X
20
IEC 947-2
220-240V
65
100
200
600V
25
35
50
380-415V
50
65
100
ICS = .25 ICU
ICW = 15 kA @ .5S
Uimp = 8kV
10
Notes
4X
Curve accuracy applies from -20°C to +55°C ambient. For possible ampere derating for ambient
above 40°C, refer to Cutler-Hammer.
Short Delay
Pick Up
Settings
(Tolerance
±10%)
6X
5
3
For ground fault time-current curves see SC-5377-92A.
8X
➀ There is a memory effect that can act to shorten the long delay. The memory effect comes into
play if a current above the long delay pick up value exists for a time and then is cleared by the
tripping of a downstream device or the circuit breaker itself. A subsequent overload will cause
the circuit breaker to trip in shorter time than normal. The amount of time delay reduction is
inverse to the amount of time that has elapsed since the previous overload. Approximately five
minutes is required between overloads to completely reset the memory.
➁ For high fault current levels a fixed instantaneous override is provided at 14000A (Tolerance
±15%).
7X
TIME IN SECONDS
2
Digitrip RMS 300 trip units are suitable for functional field testing with test kit Cat. No. STK2. For
field testing using primary injection methods, follow NEMA publication AB-4-1991.
1
➂ The end of the curve is determined by the interrupting rating of the circuit breaker. See above
tabulation.
➃ Not UL/CSA Listed.
5X
3X
.5
300 MS
.3
200 MS
.2
100MS
.1
.1
I
.03
.03
.02
.02
20
.001
CURRENT IN AMPS
October 1997
60,000
70,000
80,000
90,000
100,000
.002
50,000
.003
.002
40,000
.003
30,000
.005
20,000
.01
.005
.001
2
3
4 5 6 7 8 9 10
.5 .6 .7 .8 .9 1
CURRENT IN MULTIPLES OF RATING PLUG AMPERES (In)
Interrupting
Rating
Determines
End of Curve➂
10,000
.01
Fixed Instantaneous
Overide➁
200,000
.05
SECONDS
.05
Curve No. SC-5376-92A
Application Data
29-167N
Page 2
AB DE-ION Circuit Breakers
Types ND, CND, HND, CHND, NDC, CNDC Equipped With Type NES Digitrip RMS 310 Trip
Units With I 2t Ramp Short Time Delay (Phase Protection)
CURRENT IN MULTIPLES OF RATING PLUG AMPERES (In)
.5 .6 .7 .8 .9 1
2
3
4 5 6 7 8 9 10
20
1 HOUR
2 HOURS
10,000
Circuit Breaker Time/Current Curves (Phase Current)
Series C® N-Frame Circuit Breakers
Equipped With Type NES Digitrip RMS 310 Trip Units
The NES Digitrip RMS 310 Trip Units are AC only devices that employ microprocessor
based technology that provides true RMS current sensing means for proper correlation
with thermal characteristics of conductors and equipment. They are used with Circuit
Breaker Types ND, CND, HND, CHND, NDC, and CNDC.
5,000
3,000
I2t Ramp Short Time Delay
2,000
Typical Trip Unit Nameplate
Digitrip RMS 310 Rating Plug
Standard Fixed
Rating Plug
Push
to
Trip
Short Delay
Pickup
x In 5
4
6
Cat.–
/n–
“Y”
3
1,000
Engaged
Frame
Rating
Amperes
(Max.)
500
300
800
200
1 MINUTE
100
Long Delay➀
Maximum Total
Clearing Time
Long Delay➀
Minimum Total
Clearing Time
1200
50
30
3X
2X
8
10
TEST
Remove
Available Rating Plugs
Type
Ampere
Rating (In)
Catalog
Number
Short Delay
Pickup Range
Amperes
800
700
630
600
550
500
450
400
400, 500, 600, 800
400, 500, 630, 800
1200
1000
900
800
700
630
600
600, 800, 1000, 1200
8NES800T
8NES700T
8NES630T➃
8NES600T
8NES550T
8NES500T
8NES450T
8NES400T
A8NES800T1
A8NES800T2➃
12NES1200T
12NES1000T
12NES900T➃
12NES800T
12NES700T
12NES630T➃
12NES600T
A12NES1200T1
1600-6400
1400-5600
1260-5040
1200-4800
1100-4400
1000-4000
900-3600
800-3200
800-6400
800-6400
2400-9600
2000-8000
1800-7200
1600-6400
1400-5600
1260-5040
1200-4800
1200-9600
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Adj.
Adj.
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Fixed
Adj.
Interrupting Ratings – 50/60 Hz
RMS Sym. Amperes (kA)
UL/CSA
Breaker
Type
240V
480V
65
50
ND, CND
100
65
HND, CHND
200
100
NDC, CNDC
20
Digitrip RMS 310
Trip Unit
40°C Ambient
7
2
IEC 947-2
220-240V
65
100
200
600V
25
35
50
380-415V
50
65
100
ICS = .25 ICU
ICW = 15 kA @ .5S
Uimp = 8kV
Short Delay
Pick Up
Settings
(Tolerance
± 10%)
4X
5
3
1
Curve accuracy applies from -20°C to +55°C ambient. For possible ampere derating for ambient
above 40°C, refer to Cutler-Hammer.
Digitrip RMS 300 trip units are suitable for functional field testing with test kit Cat. No. STK2. For
field testing using primary injection methods, follow NEMA publication AB-4-1991.
8X
5X
For ground fault time-current curves see SC-5377-92A.
➀ There is a memory effect that can act to shorten the long delay. The memory effect comes into
play if a current above the long delay pick up value exists for a time and then is cleared by the
tripping of a downstream device or the circuit breaker itself. A subsequent overload will cause
the circuit breaker to trip in shorter time than normal. The amount of time delay reduction is
inverse to the amount of time that has elapsed since the previous overload. Approximately five
minutes is required between overloads to completely reset the memory.
6X
➁ For high fault current levels a fixed instantaneous override is provided at 14000A (Tolerance
±15%).
➂ The end of the curve is determined by the interrupting rating of the circuit breaker. See above
tabulation.
.5
➃ Not UL/CSA Listed.
.3
7X
.2
.1
.05
.05
.03
.03
.02
.02
20
.001
CURRENT IN AMPS
60,000
70,000
80,000
90,000
100,000
.002
50,000
.003
.002
40,000
.003
30,000
.005
20,000
.01
.005
.001
2
3
4 5 6 7 8 9 10
.5 .6 .7 .8 .9 1
CURRENT IN MULTIPLES OF RATING PLUG AMPERES (In)
Interrupting
Rating
Determines
End of Curve➂
10,000
.01
Fixed Instantaneous
Overide➁
200,000
.1
SECONDS
TIME IN SECONDS
2
Notes
Curve No. SC-5375-92A
October 1997
Application Data
29-167L
Page 2
AB DE-ION Circuit Breakers
Types LDB, LD, HLD Equipped With Type LT Thermal-Magnetic Trip Unit
60,000
70,000
80,000
90,000
100,000
50,000
40,000
30,000
20,000
6000
7000
8000
9000
10,000
5000
4000
3000
2000
600
700
800
900
1000
500
400
300
200
70
80
90
100
60
50
CURRENT IN PERCENT OF BREAKER TRIP UNIT RATING (In)
10,000
10,000
2 HOURS
Series C® L-Frame Circuit Breakers
Equipped With Type LT Thermal-Magnetic Trip Unit
5,000
Catalog Types LDB, LD, HLD Circuit Breakers, 2, 3 and 4 Poles
For application and coordination purposes only. Thermal calibration
based on 40°C ambient, cold start. Connected with four (4) feet of
rated wire (75°C) per terminal. Tested in open air with current in all
poles. Instantaneous calibration based on single-pole tests.
3,000
2,000
1 HOUR
5,000
1 HOUR
2 HOURS
Circuit Breaker Time/Current Curves
3,000
2,000
Maximum Voltage
600 V., Ac (50/60 Hz.)
250 V., Dc
1,000
1,000
Breaker Rating
Rated Amperes (In)
Instantaneous Trip Amperes
(See Figure Below)
500 to 1000% of trip unit rating (Dc values
are approximately 40% higher)
300, 350, 400,
500, 600
500
300
Maximum
240 V., (Ue)
Icu
Ics
100
LDB
LD
HLD
65
65
100
50
17
17
25
200
kA, Dc
380 V., (Ue)
Icu
Ics
415 V., (Ue)
Icu
Ics
250 V., (Ue)
Icu
Ics
40
40
65
40
40
65
10
10
20
10
10
17
10
10
17
50
Note: For additional information on the trip unit, see IL 29C606.
30
➀ Single pole data at 25°C based on NEMA Procedures
(AB 4-1991) for verifying performance of molded case circuit
breakers.
20
7.5
7.5
10
20
7.5
Push to Trip
C Thermal
Magnetic
Trip Unit
Typical
Trip Unit
Nameplate
10
100
3
3
5
Utilization Category A
UIMP = 8 kV
30
10
5
10
5
Amps
(In)
Magnetic
Multiples Of In
10
40°C
5
Cat.
No.
5
5
Individual Pole
Adjustments
3
3
2
5X
±10%
1
TIME IN SECONDS
±20%
1
10X
2
.5
.5
Adjustable Magnetic Trip
.3
.3
.2
.2
.1
.1
.05
.05
.03
Maximum Interrupting Time
.03
.02
.02
.01
.01
Interrupting Rating
Determines End of
Curve
.005
.005
CURRENT IN PERCENT OF BREAKER TRIP UNIT RATING (In)
60,000
70,000
80,000
90,000
100,000
50,000
40,000
30,000
20,000
6000
7000
8000
9000
10,000
5000
4000
3000
2000
500
600
700
800
900
1000
400
.001
300
.001
200
.002
60
.003
.002
70
80
90
100
.003
50
TIME IN SECONDS
300
250 V.
10
10
20
600 V.
25
25
35
1 MINUTE
1 MINUTE
kA, Dc
240 V.
480 V.
65
35
65
35
100
65
IEC 947-2
RMS Sym. kA, 50/60 Hz.
LDB
LD
HLD
200
Minimum
500
Interrupting Rating
Breaker
UL/CSA
Type
RMS Sym. kA, 50/60 Hz.
Maximum Single
Pole Trip Times
at 25°C 1
Curve No. SC-4547-89B
October 1997
Types FD and HFD
225 Amperes
AB DE-ION Circuit Breakers
Cutler-Hammer
30
40 50 60 70 80 90
600
700
800
900
1000
20
500
6 7 8 9 10
400
5
10,000
300
4
200
3
100
2
2 HOURS
2 HOURS
Circuit Breaker Time/Current Curves
Molded-Case Circuit Breakers
Catalog Types FD/HFD Circuit Breakers, Two, Three and Four Poles
For application and coordination purposes only.
Based on 40˚C ambient, cold start. Connected with four (4) feet of rated
wire (75˚C) per terminal. Tested in open air with current in all poles.
5,000
3,000
Maximum AC Volts: 690 at 50/60 Hz
Maximum DC Volts: 250
3,000
Breaker Rating
In Amperes
175
200
225
2,000
2,000
➀
1,000
Instantaneous Pick-up, Amperes RMS
2400
2400
2400
1 HOUR
5,000
1 HOUR
Page
Page
36a1
CURRENT IN MULTIPLES OF In
175-225A
1
Technical Data
Effective: May 1999
1,000
Interrupting Ratings
500
Maximum Single
Pole Trip Times
➁
at 25°C
300
Symmetrical RMS Amperes (kA), Icu
240 Vac
480 Vac
600 Vac
250 Vac
FD
HFD
65
100
25
65
18
25
10
22
Notes:
➀ Fixed Inverse – Time Overcurrent Release.
➁ Single Pole Test Data at 25°C based on NEMA Procedures (AB 4-1991)
for verifying performances of Molded Case Circuit Breakers.
➂ Total Operation Time.
➃ Interrupting Rating Determines End of Curve.
In this interruption region:
The curve is drawn for In = 200A. For In ≠ 200A, the end points in this
region are displaced along the current-axis by a factor (200A/In)
200
500
300
200
100
100
50
50
30
30
Maximum
Trip Time
20
20
10
10
5
5
3
3
2
Minimum
Trip Time
TIME IN SECONDS
1
TIME IN SECONDS
2
1 MINUTE
1 MINUTE
Breaker
Type
1
175 A
.5
.5
200 A
.3
.3
225 A
.2
.2
.1
.1
.05
.05
.03
.03
➂
➃
.02
.02
.01
.01
.001
1
2
3
4
5
6 7 8 9 10
20
30
40 50 60 70 80 90
CURRENT IN MULTIPLES OF In
AD 29-167F
600
700
800
900
1000
.002
500
.002
400
.003
300
.003
200
.005
100
.005
.001
Curve No. SC-6970-98A
Application Data
29-167F
Page 36
AB DE-ION Circuit Breakers
Types FDB, FD and HFD 150 Amperes
6000
7000
8000
9000
10000
5000
4000
3000
2000
600
700
800
900
1000
500
400
40 50 60 70 80 90
200
30
100
20
300
CURRENT IN AMPERES
150A
5 6 7 8 9 10
2 HOURS
Circuit Breaker Time/Current Curves
®
Series C F-Frame Circuit Breakers
Catalog Types EHD, FDB, FD and HFD Circuit Breakers, Two, Three and
Four Poles
5,000
For application and coordination purposes only.
Based on 40˚C ambient, cold start. Connected with four (4) feet of
rated wire (60˚C up to 125 amps, 75˚C above 125 amps) per terminal.
Tested in open air with current in all poles.
3,000
2,000
5,000
3,000
1 HOUR
1 HOUR
2 HOURS
10,000
2,000
Maximum AC Volts: 600 at 60 Hz
Maximum DC Volts: 250
Breaker Rating
Continuous Amperes
150 Amps
1,000
500
Maximum Single
Pole Trip Times
at 25°C 1
300
Instantaneous Trip Amperes
See Curve
Interrupting Rating (UL/CSA Listed)
Breaker Symmetrical RMS Amperes (KA)
@ 240 V., Ac @ 480 V., Ac @ 600 V., Ac
Type
FDB
FD
HFD
1
200
18
65
100
14
25
65
14
18
25
Amps (KA)
250V., Dc
10
10
22
Single pole test data at 25˚C based on NEMA Procedures
(AB 4-1991) for verifying performance of molded case circuit
breakers.
1,000
500
300
200
50
50
1 MINUTE
100
30
30
20
20
10
10
Minimum
Maximum
5
3
3
2
2
1
1
.5
.5
.3
.3
.2
.2
.1
.1
.05
TIME IN SECONDS
TIME IN SECONDS
5
1 MINUTE
100
.05
.03
.03
Maximum Interrupting Time
.02
.02
.01
.01
Interrupting
Rating
Determines
End of Curve
(See Above)
.005
.003
.002
.003
CURRENT IN AMPERES
6000
7000
8000
9000
10000
5000
4000
3000
2000
50 60 70 80 90
500
40
600
700
800
900
1000
30
400
20
300
5 6 7 8 9 10
200
.002
100
.001
.005
.001
Curve No. SC-4149-87B
October 1997
Application Data
29-167F
Page 32
AB DE-ION Circuit Breakers
Types EHD, FDB, FD and HFD 100 Amperes
6000
7000
8000
9000
10000
5000
4000
3000
2000
600
700
800
900
1000
500
400
40 50 60 70 80 90
200
30
100
20
300
CURRENT IN AMPERES
100A
5 6 7 8 9 10
2 HOURS
Circuit Breaker Time/Current Curves
®
Series C F-Frame Circuit Breakers
Catalog Types EHD, FDB, FD and HFD Circuit Breakers, Two, Three and
Four Poles
5,000
For application and coordination purposes only.
Based on 40˚C ambient, cold start. Connected with four (4) feet of
rated wire (60˚C up to 125 amps, 75˚C above 125 amps) per terminal.
Tested in open air with current in all poles.
3,000
2,000
5,000
3,000
1 HOUR
1 HOUR
2 HOURS
10,000
2,000
Maximum AC Volts: 600 at 60 Hz
Maximum DC Volts: 250
Breaker Rating
Continuous Amperes
100 Amps
1,000
Instantaneous Trip Amperes
See Curve
Interrupting Rating (UL/CSA Listed)
Breaker Symmetrical RMS Amperes (KA)
@ 240 V., Ac @ 480 V., Ac @ 600 V., Ac
Type
500
EHD
FDB
FD
HFD
300
200
1
Maximum Single
Pole Trip Times
at 25°C 1
18
18
65
100
14
14
25
65
-14
18
25
Amps (KA)
250V., Dc
10
10
10
22
Single pole test data at 25˚C based on NEMA Procedures
(AB 4-1991) for verifying performance of molded case circuit
breakers.
1,000
500
300
200
50
50
1 MINUTE
100
30
30
20
20
10
10
Minimum
Maximum
5
3
3
2
2
1
1
.5
.5
.3
.3
.2
.2
.1
.1
.05
TIME IN SECONDS
TIME IN SECONDS
5
1 MINUTE
100
.05
.03
.03
Maximum Interrupting Time
.02
.02
.01
.01
Interrupting
Rating
Determines
End of Curve
(See Above)
.005
.003
.002
.003
CURRENT IN AMPERES
6000
7000
8000
9000
10000
5000
4000
3000
2000
50 60 70 80 90
600
700
800
900
1000
40
500
30
400
20
300
5 6 7 8 9 10
200
.002
100
.001
.005
.001
Curve No. SC-4146-87B
October 1997
Application Data
29-167F
Page 28
AB DE-ION Circuit Breakers
Types EHD, FDB, FD and HFD 60 Amperes
6000
7000
8000
9000
10000
5000
4000
3000
2000
600
700
800
900
1000
500
400
40 50 60 70 80 90
200
30
100
20
300
CURRENT IN AMPERES
60A
5 6 7 8 9 10
2 HOURS
Circuit Breaker Time/Current Curves
®
Series C F-Frame Circuit Breakers
Catalog Types EHD, FDB, FD and HFD Circuit Breakers, Two, Three and
Four Poles
5,000
For application and coordination purposes only.
Based on 40˚C ambient, cold start. Connected with four (4) feet of
rated wire (60˚C up to 125 amps, 75˚C above 125 amps) per terminal.
Tested in open air with current in all poles.
3,000
5,000
3,000
1 HOUR
1 HOUR
2 HOURS
10,000
2,000
2,000
Maximum AC Volts: 600 at 60 Hz
Maximum DC Volts: 250
Breaker Rating
Continuous Amperes
60 Amps
1,000
Interrupting Rating (UL/CSA Listed)
Breaker Symmetrical RMS Amperes (KA)
@ 240 V., Ac @ 480 V., Ac @ 600 V., Ac
Type
500
EHD
FDB
FD
HFD
300
200
1
Maximum Single
Pole Trip Times
at 25°C 1
18
18
65
100
14
14
25
65
-14
18
25
Amps (KA)
250V., Dc
10
10
10
22
Single pole test data at 25˚C based on NEMA Procedures
(AB 4-1991) for verifying performance of molded case circuit
breakers.
1,000
500
300
200
100
100
50
50
30
30
20
20
Minimum
Maximum
10
10
5
5
3
3
2
2
1
1
.5
.5
.3
.3
.2
.2
.1
.1
.05
TIME IN SECONDS
TIME IN SECONDS
1 MINUTE
.05
.03
.03
Maximum Interrupting Time
.02
.02
.01
.01
Interrupting
Rating
Determines
End of Curve
(See Above)
.005
.003
.002
CURRENT IN AMPERES
6000
7000
8000
9000
10000
5000
4000
3000
2000
50 60 70 80 90
600
700
800
900
1000
40
500
30
400
20
300
5 6 7 8 9 10
200
.001
.005
.003
.002
100
1 MINUTE
Instantaneous Trip Amperes
See Curve
.001
Curve No. SC-4142-87B
October 1997
Application Data
29-167F
Page 27
AB DE-ION Circuit Breakers
Types EHD, FDB, FD and HFD 50 Amperes
6000
7000
8000
9000
10000
5000
4000
3000
2000
600
700
800
900
1000
500
400
40 50 60 70 80 90
200
30
100
20
300
CURRENT IN AMPERES
50A
5 6 7 8 9 10
2 HOURS
Circuit Breaker Time/Current Curves
®
Series C F-Frame Circuit Breakers
Catalog Types EHD, FDB, FD and HFD Circuit Breakers, Two, Three and
Four Poles
5,000
For application and coordination purposes only.
Based on 40˚C ambient, cold start. Connected with four (4) feet of
rated wire (60˚C up to 125 amps, 75˚C above 125 amps) per terminal.
Tested in open air with current in all poles.
3,000
5,000
3,000
1 HOUR
1 HOUR
2 HOURS
10,000
2,000
2,000
Maximum AC Volts: 600 at 60 Hz
Maximum DC Volts: 250
Breaker Rating
Continuous Amperes
50 Amps
1,000
Interrupting Rating (UL/CSA Listed)
Breaker Symmetrical RMS Amperes (KA)
@ 240 V., Ac @ 480 V., Ac @ 600 V., Ac
Type
EHD
14
-18
14
14
FDB
18
18
FD
65
25
HFD
100
65
25
500
300
200
1
Maximum Single
Pole Trip Times
at 25°C 1
Amps (KA)
250V., Dc
10
10
10
22
Single pole test data at 25˚C based on NEMA Procedures
(AB 4-1991) for verifying performance of molded case circuit
breakers.
1,000
500
300
200
100
100
50
50
30
30
20
20
Minimum
Maximum
10
10
5
5
3
3
2
2
1
1
.5
.5
.3
.3
.2
.2
.1
.1
.05
TIME IN SECONDS
TIME IN SECONDS
1 MINUTE
1 MINUTE
Instantaneous Trip Amperes
See Curve
.05
.03
.03
Maximum Interrupting Time
.02
.02
.01
.01
Interrupting
Rating
Determines
End of Curve
(See Above)
.005
.003
.002
.003
CURRENT IN AMPERES
October 1997
6000
7000
8000
9000
10000
5000
4000
3000
2000
50 60 70 80 90
500
40
600
700
800
900
1000
30
400
20
300
5 6 7 8 9 10
200
.002
100
.001
.005
.001
Curve No. SC-4141-87B