SIEMIENS MCCB Series Short Circuit Rating Guide

SIEMIENS MCCB Series Short Circuit Rating Guide

Deep analysis of basic information

1.1 Core positioning

Siemens focuses on the application of "series short-circuit rating" for molded case circuit breakers (MCCBs) and matching fuses. Its core goal is to provide CSA (Canadian Standards Association) certified compliant series combination solutions for distribution system design, installation, and operation personnel, solving the pain point of "insufficient branch circuit breaker breaking rating" in industrial and commercial distribution - by scientifically matching the main equipment (line side) and branch equipment (load side), while ensuring the reliability of system short-circuit protection, reducing the cost of branch equipment selection.

1.2 Scope and boundaries of application

Applicable products: Siemens' full range of molded case circuit breakers (such as QP/BQ/BL series, QPH/BQH/BLH series, ED4/ED6 series, etc.) and J/R/T/L matching fuses, covering three voltage levels: low voltage (240V), medium voltage (480V), and high voltage (600V).

Applicable scenarios: Industrial plants, commercial buildings, civil facilities, heavy machinery and other types of power distribution systems, especially suitable for circuit design with high short-circuit current but branch equipment does not need to withstand full fault current separately.

Exclusion scope: Main branch equipment combinations not explicitly listed, non Siemens original equipment, and applications beyond the voltage/current range indicated in the document are not applicable to this guideline solution.

1.3 Definition of Key Terms

Series Connected Short Circuit Rating: The maximum short-circuit breaking capacity certified by testing after the main equipment and branch equipment are connected in series. This value is allowed to be lower than the available fault current of the system, but it must meet the requirement of 'combined rated value ≤ main equipment rated value'.

Interrupting Rating: The maximum short-circuit current that the equipment can safely break independently. Circuit breakers default to a symmetrical current of 5000A rms, while fuses default to a symmetrical current of 10000A rms (with priority given to the values indicated on the equipment nameplate).

Load Side Circuit Breaker: including branch circuit breakers, branch line circuit breakers, built-in main circuit breakers, and remote main circuit breakers, which need to form a compliant series combination with the main equipment.

Core rules and general requirements

2.1 Basic principles of series combination

Mandatory certification requirement: All listed main branch equipment combinations must be CSA certified. In practical applications, it is prohibited to replace unverified models, otherwise it may result in the failure of short-circuit protection.

Rating limit: The breaking rating of the series combination shall not exceed the breaking rating of the line side equipment (main circuit breaker/fuse), and shall not exceed the short-circuit rating indicated on the equipment nameplate.

Voltage matching requirements: The voltage levels of the main equipment and branch equipment need to be adapted. For example, a 240V system cannot mix 480V equipment, and three-phase equipment (3P) needs to be matched with a three-phase circuit.

Requirements for pole number correspondence: The pole number of branch equipment (1P/2P/3P) should match the pole number and circuit type of the main equipment. 1P/2P equipment is used for single-phase circuits, and 3P equipment is used for three-phase circuits.

2.2 General Safety and Compliance Requirements

The installation of equipment should follow the specifications of the power distribution system, ensure firm wiring, good insulation, and avoid potential short circuit hazards.

The practical application of serial combination needs to be supplemented and verified based on the "CSA Certified Component Catalog" to confirm the latest compliance status of the combination.

The equipment nameplate should clearly indicate key information such as the rated breaking value, voltage, number of poles, and model. Regular checks should be conducted during operation and maintenance.

Detailed scheme for voltage classification levels

3.1 240V level

240V is the mainstream voltage level for civil and small commercial power distribution. The document provides two types of solutions: circuit breaker series connection and fuse series connection, covering four types of series rated values and the most diverse combination types.

3.1.1 Series combination of circuit breakers

Series rated value (A) Main circuit breaker core information Branch circuit breaker core information Applicable scenarios

22000 models: QPH/BQH/BLH, QNH/QNRH, EQ967 #/EQ968 #, etc

Maximum current: 70A (1P), 125A (2P), 100A (3P), 200A (2P), 225A (2P), 250A (2/3P)

Polarity: 1P/2P/3P

Voltage: 120/240V Model: QP/HQ/BL, QT, QPF/BQF/BLF, QE/BE/BLE, QAF/BAF, etc

Polarity: 1P/2P/3P

Current range: 15-20A, 15-30A, 15-50A, 15-60A, 15-70A, 15-125A

Voltage: 120V, 240V, 120/240V for residential power distribution, small commercial buildings (such as convenience stores and offices), small industrial equipment (such as small motors and pumps)

65000 models: HQP/HBQ/HBL, ED4/ED6, HNG/HNXD6, HPD6/HPXD6, etc

Maximum current: 70 A (1P)、125A (2P)、100A (3P)、150A (2P)、200A (2P)、225A (2/3P)、250A (2/3P)、400A (2/3P)、600A (2/3P)、800A (2/3P)、1200A (3P)、1600A (3P)、2000A (3P)

Polarity: 1P/2P/3P

Voltage: 120/240V, 240V Model: QP/BQ/BL、QPH/BQH/BLH、QT、QPF/BQF/BLF、QE/BE/BLE、QAF/BAF、ED2、JXD2/JD6  wait

Polarity: 1P/2P/3P

Current range: 15-20A, 15-30A, 15-50A, 15-60A, 15-70A, 15-100A, 15-125A, 100-250A, 200-400A

Voltage: 120V, 240V, 120/240V for medium-sized commercial buildings (such as shopping malls and hotels) and medium-sized industrial plants (such as light industry production lines and assembly workshops)

100000 models: CED6, HED4/HED6, HDGA/HDGB, LFGA/LFGB, etc

Maximum current: 125 A (2/3P)、150A (2/3P)、250A (2/3P)、400A (2/3P)、600A (2/3P)、800A (2/3P)、1200A (2/3P)、1600A (3P)

Polarity: 2P/3P

Voltage: 120/240V, 240V Model: QP/BQ/BL、QPH/BQH/BLH、QT、QPF/BQF/BLF、QE/BE/BLE、QAF/BAF、ED2/ED4/ED6、NJGA/NJJA  wait

Polarity: 1P/2P/3P

Current range: 15-20 A、15-30A、15-50A、15-60A、15-70A、15-100A、15-125A、50-150A、70-250A、200-400A、400-600A

Voltage: 120V, 240V, 120/240V for large commercial buildings (such as complexes and office buildings) and heavy industrial equipment (such as large compressors and fans)

200000 models: LPG, CPD6, HRD6/HRXD6, etc

Maximum current: 1600A (3P), 2000A (3P)

Polar number: 3P

Voltage: 240V Model: PD6/PXD6, HPD6/HPXD6, NJGA/NJJA, NLGA/NLGB, LD6/LXD6, etc

Polar number: 3P

Current range: 70-250A, 200-400A, 400-600A, 800-1200A, 1200-1600A, 1600-2000A

Voltage: 240V for main power distribution in large industrial plants, high-voltage motor control circuits, and critical infrastructure such as data centers and hospitals

3.1.2 Series combination of fuses (pages 63-68)

The main equipment is J/R/T/L type fuses, paired with branch circuit breakers. The core solution is as follows:

Series rated value (A) Main fuse core information Branch circuit breaker core information Applicable scenarios

6000 model: L (1,2,3P)

Maximum current: 600A

Polarity: 1P/2P/3P

Voltage: 240V Model: QPH/BQH/BLH

Polar number: 3P

Current range: 15-100A

Voltage: 120/240V for small industrial equipment clusters and commercial building power circuits

65000 model: J/R (1,2,3P), T (1,2,3P)

Maximum current: 600A, 1200A

Polarity: 1P/2P/3P

Voltage: 240V Model: QPH/BQH/BLH, QN/QNH, QNR/QNRH

Polarity: 1P/2P/3P

Current range: 15-70A, 15-125A, 150-200A

Voltage: 120/240V, 240V for medium-sized industrial production lines and commercial building central air conditioning circuits

100000 models: T (300V), L (2,3P)

Maximum current: 200A, 6000A

Polarity: 1P/2P/3P

Voltage: 240V Model: QP/HQ/BL, QPF/BQF/BLF, QE/BE/BLE, QAF/BAF, ED2/ED4/ED6, etc

Polarity: 1P/2P/3P

Current range: 15-20A, 15-30A, 15-50A, 15-100A, 15-125A

Voltage: 120V, 240V, 120/240V Emergency Power Supply Circuit for Large Commercial Buildings, Protection of Industrial Key Equipment

3.2 480V level (core content: pages 69-95)

480V is the mainstream voltage level for industrial power distribution, mainly for three-phase equipment, with series rated values covering the medium to high range, suitable for various industrial scenarios.

3.2.1 Circuit Breaker Series Combination (Pages 69-92)

Series rated value (A) Main circuit breaker core information Branch circuit breaker core information Applicable scenarios

25000 model: NGB/HGB/LGB (2,3P)

Maximum current: 125A

Polarity: 2P/3P

Voltage: 277/480V Model: BQD/CQD

Polarity: 1P/2P/3P

Current range: 15-100A

Voltage: 277V, 277/480V Small industrial plants (such as electronics factories, light industry workshops), large equipment in commercial buildings (such as chillers)

30000 model: HED6 (2,3P)

Maximum current: 125A

Polarity: 2P/3P

Voltage: 480V Model: BQD/CQD

Polarity: 2P/3P

Current range: 15-70A

Voltage: 277/480V Industrial auxiliary equipment (such as water pumps, fans), commercial building power distribution

35000 models: JD6-A/JXD6-A (2,3P), HJD6-A/HJXD6-A (2,3P), HLD6-A/HLXD6-A (2,3P)

Maximum current: 400A, 600A

Polarity: 2P/3P

Voltage: 480V Model: NGB, HFD6/HFXD6, NJGA/NJJA

Polarity: 2P/3P

Current range: 15-125A, 70-250A, 200-400A

Voltage: 277/480V, 480V for medium-sized industrial production lines (such as mechanical processing, automotive parts manufacturing), large commercial buildings (such as shopping centers)

42000 model: HED4 (2,3P)

Maximum current: 125A

Polarity: 2P/3P

Voltage: 480V Model: ED4/ED6

Polarity: 2P/3P

Current range: 15-125A

Voltage: 480V industrial motor control circuit, emergency power supply system

50000 models: HFD6/HFXD6 (2,3P), MD6/MXD6 (2,3P), ND6/NXD6 (2,3P)

Maximum current: 250A, 800A, 1200A, 1600A, 2000A

Polarity: 2P/3P

Voltage: 480V Model: NGB/HGB, NJGA/NJJA, NLGA/NLGB, LD6/LXD6

Polarity: 2P/3P

Current range: 15-125A, 200-400A, 400-600A, 600-800A, 800-1200A

Voltage: 277/480V, 480V for large industrial plants (such as chemical and metallurgical industries) and heavy machinery (such as machine tools and cranes)

65000 models: HMG (2,3P), HMD6/HMXD6 (2,3P), HNG/HNXD6 (2,3P)

Maximum current: 800A, 1200A, 1600A

Polarity: 2P/3P

Voltage: 480V Model: NDGA/NDGB, NFGA/NFGB, FXD6/FD6, NJGA/NJJA

Polarity: 2P/3P

Current range: 50-150A, 70-250A, 200-400A, 400-600A

Voltage: 480V for heavy industrial production lines, high-voltage motor clusters, and critical industrial facilities (such as power plant auxiliary systems)

100000 models: LMG (2,3P), CMD6 (3P), LNG (2,3P)

Maximum current: 800A, 1200A, 1600A

Polarity: 2P/3P

Voltage: 480V Model: HFD6/HFXD6, JD6/JXD6, HLD6/HLXD6, ND6/NXD6

Polarity: 2P/3P

Current range: 70-250A, 200-400A, 400-600A, 500-800A, 800-1200A

Voltage: 480V Main Distribution for Large Chemical Industrial Parks, Metallurgical Plants, and Data Centers

150000 model: CJD6 (- A) (2,3P)

Maximum current: 400A

Polarity: 2P/3P

Voltage: 480V Model: HFD6/HFXD6, JXD6/JD6, HJD6/HJXD6

Polarity: 2P/3P

Current range: 70-250A, 200-400A

Voltage: 480V Extra Large Industrial Equipment, High Voltage Power Circuit

200000 model: CED6 (3P)

Maximum current: 125A

Polar number: 3P

Voltage: 480V Model: ED4/ED6, NGB/HGB/LGB

Polar number: 3P

Current range: 15-125A

Voltage: 277/480V critical infrastructure (such as hospitals, airports), industrial emergency support circuits

3.2.2 Series combination of fuses (pages 93-95)

Series rated value (A) Main fuse core information Branch circuit breaker core information Applicable scenarios

50000 model: J (1,2,3P)

Maximum current: 400A

Polarity: 1P/2P/3P

Voltage: 480V Model: ED4

Polarity: 1P/2P/3P

Current range: 15-100A

Voltage: 277V, 480V for industrial auxiliary circuits and large-scale air conditioning systems in commercial buildings

100000 models: T/J/R (2,3P), L (2,3P)

Maximum current: 600A, 1200A

Polarity: 2P/3P

Voltage: 480V Model: FXD6/FD6, NDGA/NDGB, NJGA/NJJA, LD6/LXD6

3.3 600V level

600V is the high voltage industrial application level, and the equipment needs to withstand higher insulation requirements. The upper limit of the series rated value is relatively low, focusing on high voltage industrial scenarios.

3.3.1 Series combination of circuit breakers

Series rated value (A) Main circuit breaker core information Branch circuit breaker core information Applicable scenarios

14000 model: NGB2 (2,3P)

Maximum current: 125A

Polarity: 2P/3P

Voltage: 347/600V Model: BQD6

Polarity: 1P/2P/3P

Current range: 15-70A

Voltage: 347V, 347/600V High Voltage Small Equipment (such as High Voltage Pumps, Fans), Industrial Auxiliary High Voltage Circuits

18000 models: ED6/HED6 (1,2,3P), ED6 (2,3P)

Maximum current: 125A

Polarity: 1P/2P/3P

Voltage: 347/600V, 600V Model: BQD6, NGB/NGB2

Polarity: 1P/2P/3P

Current range: 15-70A, 15-125A

Voltage: 347V, 347/600V, 600V Industrial High Voltage Motor Control, High Voltage Production Line Auxiliary Circuit

22000 model: HGB2 (2,3P), LGB2 (2,3P)

Maximum current: 125A, 250A

Polarity: 2P/3P

Voltage: 347/600V Model: BQD6, NGB/NGB2

Polarity: 1P/2P/3P

Current range: 15-70A, 15-125A

Voltage: 347V, 347/600V for medium high voltage industrial equipment and chemical high voltage circuits

25000 model: HFD6/HFXD6 (2,3P)

Maximum current: 250A

Polarity: 2P/3P

Voltage: 347/600V, 600V Model: BQD6, ED6/HED6, NGB/NGB2/HG22

Polarity: 1P/2P/3P

Current range: 15-70A, 15-125A

Voltage: 347V, 347/600V, 600V High Voltage Industrial Production Line, Heavy Machinery High Voltage Power Circuit

35000 models: HJD6 (- A)/HJXD6 (- A) (2,3P), HLD6 (- A)/HLXD6 (- A) (2,3P)

Maximum current: 400A, 600A

Polarity: 2P/3P

Voltage: 600V Model: HFD6, NJGA/NJJA, LD6 (- A)/HLD6 (- A)

Polarity: 2P/3P

Current range: 70-250A, 200-400A, 200-600A, 450-600A

Voltage: 600V for large high-voltage industrial equipment (such as high-voltage compressors and generators) and high-voltage distribution in chemical industrial parks

50000 models: HMD6/HMXD6 (2,3P), HND6/HNXD6 (2,3P)

Maximum current: 800A, 1200A

Polarity: 2P/3P

Voltage: 600V Model: HFD6, JD6 (- A)/JXD6 (- A), LD6 (- A)/HLD6 (- A)

Polarity: 2P/3P

Current range: 70A, 200-400A, 200-600A, 450-600A

Voltage: 600V Heavy Industry High Voltage Main Distribution, Power Plant Auxiliary High Voltage Circuit

65000 models: CFD6 (2,3P), CMD6 (2,3P), CND6 (2,3P), CPD6 (2,3P)

Maximum current: 250A, 800A, 1200A, 1600A

Polarity: 2P/3P

Voltage: 600V Model: BQD6, ED6/HED6, HFD6, JD6 (- A)/JXD6 (- A)

Polarity: 2P/3P

Current range: 15-70A, 15-125A, 70-250A, 200-400A

Voltage: 347/600V, 600V High Voltage Circuit for Large Chemical Enterprises and Metallurgical Factories

100000 models: CED6 (2,3P), CFD6 (2,3P)

Maximum current: 125A, 250A

Polarity: 2P/3P

Voltage: 347/600V, 600V Model: BQD6, ED6/HED6, HFD6, NGB/NGB2/HG22/LG22

Polarity: 1P/2P/3P

Current range: 15-70A, 15-125A, 70-250A

Voltage: 347V, 347/600V, 600V Key high-voltage infrastructure (such as high-voltage data centers, large hospital high-voltage systems)

3.3.2 Series combination of fuses

Series rated value (A) Main fuse core information Branch circuit breaker core information Applicable scenarios

100000 model: J/R/T (2,3P)

Maximum current: 600A

Polarity: 2P/3P

Voltage: 600V Model: JD6 (- A)/JXD6 (- A), HJD6 (- A)/HJXD6 (- A), LD6 (- A)/HLD6 (- A)

Polarity: 2P/3P

Current range: 200-400A, 200-600A, 450-600A

Voltage: 600V High Voltage Industrial Plant, Heavy Machinery High Voltage Circuit

Analysis of Equipment Model System and Key Parameters

4.1 Classification and Characteristics of Main Equipment Models

4.1.1 Circuit Breaker Series

QP/BQ/BL series: Basic plastic case circuit breaker, suitable for 240V low voltage scenarios, current range 15-125A, pole number 1P/2P/3P, voltage adaptation 120V/240V/120/240V, is the main model for civilian and small commercial use.

QPH/BQH/BLH series: Enhanced low-voltage circuit breaker, current range 15-125A, pole count 1P/2P/3P, compatible with 240V/480V, with higher breaking capacity, suitable for medium-sized commercial and industrial scenarios.

ED4/ED6 series: Universal circuit breaker, covering 240V/480V, current range 15-125A, pole count 1P/2P/3P, strong compatibility, suitable for multi scene distribution.

FD6-A/FXD6-A series: High voltage dedicated circuit breaker, suitable for 480V/600V, current range 70-250A, pole count 2P/3P, designed for industrial high-voltage circuits.

MD6/MXD6 series: Large industrial circuit breaker, suitable for 480V/600V, current range 400-800A, pole count 2P/3P, used for main power distribution in large industrial plants.

4.1.2 Fuse series

J-type fuse: universal type, suitable for 240V/480V/600V, maximum current 600A, pole count 1P/2P/3P, suitable for various medium and low voltage scenarios.

R-type fuse: enhanced type, suitable for 240V/480V, maximum current 1200A, 2P/3P poles, high breaking capacity, suitable for industrial high-voltage circuits.

T-type fuse: High voltage dedicated type, suitable for 240V/480V/600V, maximum current 1200A, 2P/3P poles, excellent insulation performance, suitable for high-voltage industrial scenarios.

L-type fuse: extra large, suitable for 240V/480V, maximum current 6000A, 2P/3P poles, extremely strong breaking capacity, used for large industrial critical circuits.

4.2 Core parameters of branch circuit breakers

Pole numbers: 1P (single-phase circuit), 2P (single-phase/two-phase circuit), 3P (three-phase circuit), must be strictly matched with the main equipment and distribution system type.

Current range: 15-20A (small load), 15-30A (lighting/socket), 15-50A (small motor), 15-70A (medium load), 15-125A (large load), 200-400A (industrial equipment), 400-600A (main circuit), etc., depending on the load power selection.

Voltage adaptation: 120V (single-phase low voltage), 240V (single-phase medium voltage), 277V (three-phase lighting), 347V (high-voltage lighting), 480V (three-phase industrial), 600V (high-voltage industrial), which should be consistent with the system voltage.

Key application suggestions and precautions

6.1 Selection Core Suggestions

Voltage priority matching: First, clarify the voltage of the distribution system (240V/480V/600V), and then select the combination from the corresponding voltage section to avoid cross voltage selection.

Accurate current adaptation: Select the current range of the branch circuit breaker based on the actual load current, and ensure that the maximum current of the main equipment is greater than or equal to the maximum current of the branch equipment.

Scenario specific selection: QP/BQ/BL series+J-type fuses are preferred for civilian/small commercial use; FD6-A/FXD6-A series+T/L type fuses are preferred for high voltage in industry; Priority should be given to selecting the 100000A/200000A combination with higher certification levels for key facilities.

6.2 Installation and operation precautions

During installation, it is necessary to verify the model, number of poles, voltage, current, and other parameters of the main and branch equipment to ensure consistency with the document combination. Mixing unverified equipment is prohibited.

Regularly check the information on the equipment nameplate, confirm whether the rated value of the disconnection and the serial combination identification are clear, and replace the nameplate in a timely manner if there is wear and tear.

After a short circuit fault, it is necessary to check all devices in the series combination. If the main device triggers a disconnection, the status of the branch devices should be checked synchronously to ensure that there is no hidden damage.