Industrial Automation
Catalog Section - U906
Circuit Breakers
NRBM Series
Circuit Breakers
For up-to-date information, or to request a
full copy of this catalog, contact us at
www.idec.com
or
800-262-IDEC.
.
Due to continuous product improv ements,
specifications are subject to change
wihtout notice.
Circuit Breakers
Selection Guide
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Selection Guide: NRBM and NRC Series
1. For NRBM dimensions, see page N-25.
2. For NRC dimensions, see page N-26.
3. All switch only units are not CSA certified.
4.UL recognized, applicable standard: UL1077, “Supplementary Protectors.”
5. Not suitable for branch circuit protection.
Series Model NRBM NRC
Page
N-12 N-19
Appearance
Actuator Style
Lever Slide, lever
Protection Method
Electromagnetic trip
Number of Poles
1, 2, 3 1, 2
Internal Circuits
Series current trip Series current trip
Auxiliary Contact
Optional (250V AC, 5A; 50V DC, 1A)
Alarm Contact
Optional (250V AC, 5A; 50V DC, 1A)
Inertia Delay
Optional (for resistance to high inrushes) —
Time Delay Curves
2 types for DC; 3 types for AC 2 types for DC; 2 types for AC
Rated Voltage
250V AC, 50/60Hz, 65V DC
Rated Tripping Currents
1A, 2A, 3A, 5A, 7.5A, 10A, 15A, 20A, 25A, 30A, 40A, 50A 0.30A, 0.5A, 0.75A, 1A, 2A, 3A, 5A, 7.5A, 10A, 15A,
20A, 25A, 30A
Rated Interruption Capacity
1000A, 250V AC (50/60Hz), 65V DC
2,500A, 220V AC 50/60Hz (1-pole)
1,500A, 220V AC 50/60Hz (2-pole)
1,500A, 65V DC (1-pole)
1000A, 65V DC (2-pole)
Approvals
UL, CSA UL, CSA
Selection Guide, continued
CSA Certified
File No. LR47985
UL Recognized
File No. E68029
Circuit Breakers NRBM Series
N-12 www.idec.com USA: (800) 262-IDEC or (408) 747-0550, Canada (888) 317-IDEC
N1. Not suitable for branch circuit protection.
General Specifications
Protection Method Electromagnetic tripping
Internal Circuit Series current trip
Number of Poles 1, 2, 3
Rated Voltage 250V AC, 50/60Hz, 65V DC
Rated Tripping Currents Current trip: 1A, 2A, 3A, 5A, 7.5A, 10A, 15A, 20A, 25A, 30A, 40A, 50A
Rated Interrupting Capacity 250V AC, 50/60Hz, 1,000A
65V DC, 1,000A
Auxiliary Contacts
Alarm Contact
SPDT microswitch
250V AC, 5A (resistive load)
50V DC, 1 A (resistive load)
Reference Temperature 25°C
Ambient Operating Temperature –40 to +85°C (avoid freezing)
Insulation Resistance 100MΩ minutes (measured with 500V megger)
Dielectric Strength Between main circuit terminals: 2,000V AC, 1 minute
Between main circuit and auxiliary contact: 2,000V AC, 1 minute
Vibration Resistance 100N (approximately 10G), 10 to 55Hz
Shock Resistance 1,000N (approximately 100G)
Life Expectancy 10,000 operations minimum (at 6 operations per minute)
Terminal Style Main terminal: M5 stud
Auxiliary contact/ alarm contact: Quick-connect tab 0.110" terminal
Weight 1-pole/100g
2-pole/200g
3-pole/300g
NRBM Series
NRBM circuit breakers are the largest in rated current (1A to 50A)
among the IDEC circuit breakers series. These small sized, high-
efficiency breakers offer a variety of protection characteristics
that can be widely employed for semiconductors, relay circuits,
heater circuits, transformers, and solenoids.
Key features of the NRBM series include:
• Available with different internal circuits
• Excellent overload and short circuit protection
• Small size and high efficiency
• Life expectancy of over 10,000 operations
• UL1077 recognized “Supplementary Protectors”
CSA Certified
File No. LR47985
UL Recognized
File No. E68029
Circuit Breakers NRBM Series
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NRBM series part numbers are composed of 6 part number codes. When ordering an NRBM series part, select one code from each category.
Example: NRBM 1 1 11 F-30A-AA
Part Number Codes: NRBM Series
1. For NRBM series accessories, see page N-15.
2. For NRBM series time delay curves, see page N-16.
3. For NRBM series dimensions, see page N-25.
4. Not suitable for branch circuit protection.
5. UL recognized, applicable standard: UL1077, “Supplementary Protectors.”
6. Switch only types are not CSA certified.
Description Part Number Code Remarks
➀ No. of Poles
1-pole 1
All multiple circuit breakers are simultaneous throw/simulta-
neous break. All levers are mechanically interlocked.
2-pole 2
3-pole 3
➁ Internal Circuit Series current trip 1
➂ Auxiliary and
Alarm Contacts
Without 00
Alarm contacts are available only on series trip units. With auxiliary contact 11
With alarm contact 21
➃ Inertia Delay Without inertia delay Blank Inertia delay is available with curves AD, MD, AA, BA, and MA.
With inertia delay F
⑤ Rated Current Rated current (series current trip) 1A, 2A, 3A, 5A, 7.5A, 10A, 15A,
20A, 25A, 30A, 40A, 50A
All current ratings must be listed in amps (A).
Example conversions: 50mA = 0.05A, 300mA = 0.30A.
Leave blank for switch only units.
➅ Time Delay
Curve
DC curves AD, MD See page N-16 for delay curves.
Leave blank for switch only units.
AC curves AA, BA, MA
Part Numbering Guide
➀ Poles
111 F 30A AA
NRBM 1
➁ Internal
Circuit ➂ Auxiliary and
Alarm Contacts ➃ Inertia
Delay ⑤ Rated Current ➅ Time Delay
Circuit Breakers NRBM Series
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Time Delay Curve Descriptions
Inertia Delay Descriptions
Circuit breakers equipped with inertia delay do not respond to high inrush currents such as
those produced by transformer, lamp, or motor loads, but perform the specified interruption
on the rated overcurrents.
Inertia delay is available with time delay curves AD, MD, AA, BA, and MA.
Specify inertia delay by inserting an “F” in the part number as shown in Part Number Guide
on previous page.
Multi-Pole
Multi-pole types such as 2- or 3-pole should be assembled by IDEC.
Because of their characteristics, 1-pole breakers cannot be combined to provide multi-pole units.
All multi-pole units are simultaneous break/simultaneous make, with levers mechanically
interlocked.
Auxiliary and Alarm Contacts
Multi-pole units with auxiliary contacts will have one set of auxiliary contacts on the right-
most breaker. Multi-pole units with alarm contacts will have one set of alarm contacts on
the left-most breaker.
Time Delay Curve NRBM Application
AD, AA Common curves used in molded-case circuit breakers.
BA
Response to overcurrent is quite fast. Suited for protection of semiconductor circuits with
very little overload tolerance. If overcurrents are expected to flow, fuses may be required
according to the circuit characteristics.
MD, MA Suited for motor loads that draw high inrush currents lasting a considerable length of time.
With Inertia Delay Designed not to trip on 20 times the rated current (peak value) for a duration of 8ms. Suited for
transformer and lamp loads that draw steep inrush currents.
Information About Circuit Breakers
Pulse Peak
Pulse (Duration)
16,000
14,000
12,000
10,000
8,000
6,000
4,000
2,000
12345678910
Current
Width
Pulse Width (ms)
Percent of Rated Current
1. Percent of Rated Current =
2. Based on sinusoidal or parabolic pulse profile.
x 100%
Pulse Peak Current
Protector Rated Current
Notes
Circuit Breakers NRBM Series
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Part Numbers: NRBM Mounting Accessories
For dimensions of NRBM series accessories, see page N-25.
Description Appearance Part No. Remarks
Terminal Socket MS-1C For connection with auxiliary
or alarm contact terminals.
Accessories
Internal Circuits and Terminal Arrangements
LINE
LOAD
Series Current Trip
NC
NO
LINE
C
LOAD
Series Current Trip
NO
NC
LINE
C
LOAD
Series Current Trip
with Auxiliary Contacts with Alarm Contacts
Circuit Breakers NRBM Series
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Overcurrent — Time Delay Characteristics (at 25°)
1. All values above are in seconds.
2. Data in this table is equivalent to information presented in following time delay curves.
Percent of Rated Current
Curve 100% 125% 150% 200% 400% 600% 800% 1000%
DC
AD No trip 10 – 130 6 – 55 2.6 – 20 0.5 – 3.5 0.14 – 1.4 0.008 – 0.7 0.005 – 0.35
MD No trip 35 – 400 20 – 180 8 – 60 1.6 – 10 0.6 – 4.5 0.01 – 2 0.007 – 0.5
AC (50/60Hz)
AA No trip 15 – 120 8 – 45 3 – 15 0.48 – 2.5 0.06 – 0.8 0.007 – 0.13 0.005 – 0.04
BA No trip 0.75 – 10 0.45 – 3.5 0.22 – 1.3 0.045 – 0.22 0.012 – 0.12 0.005 – 0.06 0.004 – 0.03
MA No trip 70 – 900 30 – 260 10 – 70 1.8 – 11 0.5 – 4 0.009 – 1.1 0.006 – 0.2
Time Delay Curves (numerical equivalent)
DC Time Delay Curves
1,000
100
10
1
0.1
0.01
100
125
200 300 400 500 600 700 800 900 1,000
Time in Seconds
Percent of Rated Current
AD Delay Curve
at 77˚F (25˚C)
1,000
100
10
1
0.1
0.01
100
125
150
200 300 400 500 600 700 800 900 1,000
Time in Seconds
Percent of Rated Current
MD Delay Curve
at 77˚F (25˚C)
Circuit Breakers NRBM Series
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AC (50/60Hz) Time Delay Curves: NRBM Series
1,000
100
10
1
0.1
0.01
100
125
150
200 300 400 500 600 700 800 900 1,000
Time in Seconds
Percent of Rated Current
AA Delay Curve
at 77˚F (25˚C)
1,000
100
10
1
0.1
0.01
100
125
150
200 300 400 500 600 700 800 900 1,000
Time in Seconds
Percent of Rated Current
BA Delay Curve
at 77˚F (25˚C)
1,000
100
10
1
0.1
0.01
100
125
150
200 300 400 500 600 700 800 900 1,000
Time in Seconds
Percent of Rated Current
MA Delay Curve
at 77˚F (25˚C)
Circuit Breakers NRBM Series
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Resistance and Impedance Characteristics
Coil Data for series Current Trip at 25˚C
Tolerance ±25% (up to 20A), ±50% (25A and over)
Voltage Drop Due to Coil Resistance or Impedance
The internal resistance or impedance of a circuit breaker tends to be larger for
a smaller rated current. Therefore, when circuit breakers of a small rated cur-
rent are used, voltage drop should be taken into consideration. Internal resis-
tance also varies with time delay curves, even at the same rated current. This
should also be considered during installation.
Time Delay Curve and Ambient Temperature
Since NRBM series circuit breakers employ an electromagnetic tripping sys-
tem, the rated current (trip current) is not affected by the ambient temperature,
but the time delay varies with the oil viscosity in the tube. Lower oil viscosity at
higher temperatures results in shorter delay; whereas at lower temperatures,
the delay will be prolonged. The time delay curves, shown starting on page N-
16, are at 25°C. Time delay curves can be corrected.
Rated
Current DC Resistance AC Impedance
(50/60Hz)
Curves AD, MD Curves AA, BA, MA
0.05A 382Ω430Ω
0.10A 85.4Ω110Ω
0.25A 12.6Ω16Ω
0.03A 9.2Ω12Ω
0.50A 3.76Ω4.3Ω
0.75A 1.47Ω1.75Ω
1A 1Ω1.1Ω
2A 0.227Ω0.245Ω
3A 0.091Ω0.11Ω
5A 0.035Ω0.039Ω
7.5A 0.015Ω0.018Ω
10A 0.0088Ω0.0124Ω
15A 0.005Ω0.0065Ω
20A 0.003Ω0.0047Ω
25A 0.0023Ω0.0032Ω
30A 0.0019Ω0.0031Ω
40A 0.0018Ω0.002Ω
50A 0.0014Ω0.0016Ω
100
10
1
0.1
0.01
0.001 0.01 0.1 1 10 100
Rated Current (A)
Coil Resistance (Ω)
Coil Resistance at 25°C
Curves AD, BD, CD, MD, ED
100
10
1
0.1
0.01
0.001 0.01 0.1 1 10 100
Rated Current (A)
Impedance (Ω)
Curves AA, BA, CA, MA, EA
200
100
80
60
40
–40 –20 025 50 70
Rated Current (A)
Ambient Temperature (°C)
400
90
Curves AD, AA, BA
(on 125% rated current)
Circuit Breakers Instructions
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.
Description Circuit Example
Series Trip
This is the most common circuit breaker, providing excellent overload and short circuit
protection. It can also be used as an ON/OFF switch.
Series Trip with Auxiliary Contact
Since the auxiliary contact operation is interlocked with the ON/OFF of the main contactor,
circuit breaker operation can be monitored by a lamp or buzzer. This circuit breaker can
also be used to control auxiliary circuits up to 250V AC/5A (resistive load).
Series Trip with Alarm Contact
Since the alarm contact is electrically independent of the main contactor, but actuates
when the protective element operates. The alarm can be used with a lamp or buzzer to
monitor trip operations, and can also be used for controlling alarm circuits. The contact
rating is 250V AC/5A (resistive load).
Instructions: All Series
General
IDEC’s circuit breakers have been developed for the protection of electrical
circuits and small-sized electrical equipment and provide excellent protection
against overloads and short-circuits.
Additionally, IDEC’s circuit breakers are designed to suit specific needs. Each
series offers unique circuit protection characteristics and a choice of actuator
styles.
IDEC’s Circuit Breaker Features
• Various models are available with different internal circuits, tripping charac-
teristics, and rated currents
• 1- to 3- multi-pole
• Inertia delay
• Auxiliary contacts and alarm contacts
• The electromagnetic tripping system is not affected by ambient temperature
• Safe trip-free mechanism
• Vibration- and impact-resistant design
• When using accessories such as plug-in bases, flush plates, and colored
caps, a variety of mounting styles is possible — such as DIN rail mount-
ing, snap mounting into panel cut-outs, and color-coded arrangement on
the panel
Mounting Instructions: Installation Angle
Designed to be mounted on a vertical surface, the circuit breakers should be
mounted on a surface within 10° of the vertical plane. If the circuit breaker is
mounted on a horizontal surface or at any angle other than the specified
angle, its characteristics will be changed.
Multi-Pole Assemble
Multi-pole types such as 2- or 3-pole should be assembled by IDEC.
Because of their characteristics, 1-pole breakers cannot be com-
bined to produce multi-pole units.
Applications
The IDEC NRA circuit breaker series features superior overload and short-cir-
cuit protection. Many combinations of protection mechanisms and internal
circuit connections enable wide applications.
• Precision measuring instruments: electronic counters, projection
instruments, oscilloscopes, industrial instrumentation, and analytic
devices
• Electronic communication devices: facsimile machines, computers,
recorders
• Industrial machinery: printers, elevators, cranes
• Chemical and food industry machines: vacuum devices, wrappers,
centrifuges, agitators
• Machine tools: mill grinders, drills, presses
• Business machines: automatic vendors, medical equipment, beauty
salon equipment, entertainment games
• Other: office equipment, air-conditioners, conveyor belts, and many more
How the Breaker Operates
IDEC’s hydraulic magnetic circuit breakers operate like a solenoid coil. The
coil unit consists of an oil-filled tube with a metal core at one end and a pole
piece and armature at the opposite end with a spring in between.
When a current load passes through the coil winding, it creates a magnetic
field. As long as the current load is either at or below the nominal rating of
the breaker, the metal core will remain stationary.
If the current load increases beyond the nominal rating, the strength of the
magnetic field causes the core to move toward the pole-end of the tube. The
oil viscosity regulates the core’s movement through the tube, thereby regulat-
ing the time delay. As the percentage of current load increases, the required
trip time of the breaker decreases and vice versa.
When the current reaches the overload rating, the metal core will meet the
pole piece at the opposite end of the tube. At this point, the armature is
attracted to the same pole piece, tripping the breaker.
In case of sudden short circuit, the magnetic field created will instantly trip
the breaker.
Internal Circuits Overview
Load
Load A
Load B
Load A
Load B
Circuit Breakers Dimensions
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Dimensions
Dimensions: NRA Series
0.745"
(19.1mm) 0.745"
(19.1mm) 0.745"
(19.1mm)
1.65" (42.2mm)
2.03" (52mm)
1-pole: 0.745" (19.1mm)
2-pole: 1.49" (38.2mm)
3-pole: 2.23" (57.3mm)
1.20"
(30.8mm)
60°
0.250" Tab Terminal
0.110" Tab Terminal
1.56" (40mm)
1.56" (40mm)
1.93" (49.5mm)
2.11" (54mm)
0.683"
(17.5mm)
NRAS
0.745"
(19.1mm) 0.745"
(19.1mm) 0.745"
(19.1mm)
2.03" (52mm)
1.65"(42.2mm)
1.23"(31.5mm)
1-pole: 0.745" (19.1mm)
2-pole: 1.49" (38.2mm)
3-pole: 2.23" (57.3mm)
1.20"
(30.8mm)
0.250" Tab Terminal
0.110" Tab Terminal
1.56" (40mm)
0.644"
(16.5mm)
1.60" (41mm)
1.97" (50.5mm)
2.11" (54mm)
60°
NRAN
0.745"
(19.1mm)
LED
ON
OFF
1.23" (31.5mm)
1.65" (42.2mm)
2.03" (52mm)
0.250" Tab Terminal
0.110" Tab Terminal
0.78" (20mm)
1.56" (40mm)
0.417"
(10.7mm)
2.18" (56mm)
2.55" (65.5mm)
2.69" (69mm)
NRAR
1.20"
(30.8mm)
Dimensions: NRBM Series
0.745"
(19.1mm) 0.745"
(19.1mm) 0.745"
(19.1mm)
1.37" (35mm)
2.04" (52.3mm)
2.46" (63mm)
1-pole: 0.745" (19.1mm)
2-pole: 1.49" (38.2mm)
3-pole: 2.23" (57.3mm)
1.35"
(34.7mm)
60°
M5 Stud 0.110" Tab Terminal
1.92” (49.2mm)
0.8"
(20.5mm)
1.85" (47.5mm) 0.624"
(16mm)
2.48" (63.5mm)
NRBM
Circuit Breakers Dimensions
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NRBM Series
NRC Series
All drawings are not to scale unless scale is indicated.
0.745" (19.1mm)
1.38" (35.5mm)
2.04" (52.3mm)
1-Pole: 0.764"
(19.6mm)
2-Pole: 1.51" (38.7mm)
3-Pole: 2.25" (57.8mm)
NRBM
0.33" (8.4mm)
Panel Cut-Outs, continued
2-M4 Holes
.472" (12mm)
2.11" (54mm)
(4.5mm)
Surface Mounting Hole Layout 1-Pole
2-M4 Holes
1.45" (37mm)
2.11" (54mm)
(4.5mm)
Surface Mounting Hole Layout 2-Pole
Scale: Full Size
