Solar Circuit Breakers: The difference between DC and AC breakers

DC Circuit Breaker - Miniature Circuit Breakers for DC and Solar Generation

The JB is a DC circuit breaker dedicated to multi string photovoltaic installations.
This circuit breaker is designed to protect the cables located between each string of photovoltaic modules and the photovoltaic inverter against overloads and short circuits.
Combined with a switch , the JB will be installed in a string PV protection enclosure at the end of each string of photovoltaic modules.
It can be locked (by a padlocking device) in OFF position as a safety measure for removal of the PV inverter.
Since a fault current can flow in the reverse direction to the operating current, the JB can detect and protect against any bidirectional current.
To ensure the safety of the installation, it is necessary, depending on the various types of application, to combine the JB with:

a residual current device at the AC end

a fault passage detector (insulation monitoring device) at the DC end

an earth protection circuit breaker at the DC end


  • In all cases, fast action on site will be required to clear the fault (protection not ensured in the event of a double fault).
  • JB is not polarity sensitive: (+) and (-) wires can be inverted without any risk.

Meaning and classification models

DC Circuit Breaker

Main characteristics

Operating Voltage (Ue) 1P=250 V DC, 2P=500 V DC
3P=750 V DC, 4P=1000 V DC
Rated insulation voltage (Ui) 1,000 VDC
Breaking capacity (Icu) 10 kA
Impulse voltage (Uimp) 4 kA
Electrical connection By the bottom for In and Out
Number of poles 1P, 2P, 3P, 4P
Standards IEC 60947-2
EN 60947-2

Technical data

  • Position contact indication – suitability for isolation according to IEC/EN 60947-2 standard.
  • The presence of the green strip guarantees physical opening of the contacts and allows operations to be performed on the downstream circuit in complete safety.
  • Increased product service life thanks to fast closing independent of the speed of actuation of the toggle.
  • Pre-wired product: Input / Output on the same side.
Rated service breaking capacity (Ics) 100 % of the Icu
Endurance (O-C) Electrical 1,500 cycles (where L/R=2 ms)
Mechanical 20, 000 cycles
Mechanical 20, 000 cycles
Degree of pollution 2
Category A (no delay in accordance with IEC / EN 60947-2 standards)
Degree of protection
(IEC 60529)
Tropicalisation Relative humidity: 95 % at 55°C in accordance with
IEC 60068-2 and GB 14048.2 standards
Temperature Operating -25°C to 70 °C
Storage -40°C to 85°C


DC Circuit Breaker C curve

DC Circuit Breaker K curve

Instantaneous Trip

B Curve
These MCBs are suitable for cable protection.
Rating: 1-63A(30℃)
Instantaneous trip: (3-5)In
C Curve
Suitable Domestic and residential applications and electromagnetic starting loads with
medium starting currents.
Rating: 1-63A(30℃)
Instantaneous trip: (7-10)In
D Curve
Suitable for inductive and motor loads with high starting currents.
Rating: 1-63A(30℃)
Instantaneous trip: (10-14)In
K Curve
Suitable for inductive and motor loads with high inrush currents.
Rating: 1-63A(30℃)
Instantaneous trip: (14-18)In

Wiring Diagram

DC Circuit Breaker Diagrams


DC Circuit Breaker Installation

Dimensions (mm)

DC Circuit Breaker Dimensions

Weight (g)

Circuit breaker
Type 1P 2P 3P 4P
Weight (g) 120 240 360 480


DC Circuit Breaker Connection

AC Vs DC Circuit Breakers: The importance of the DC ARC Extinguisher


DC Circuit Breaker JB Application Railway

Application #1 Railway

DC circuit breakers are crucial for ensuring safety and reliability of power systems in railways. These breakers are capable of quickly detecting faults in circuits and cutting off the current to prevent damage to electrical equipment or potential fires. In railway systems, DC circuit breakers can also assist with controlling the operation and stopping of trains, as well as optimizing energy usage.

DC Circuit Breaker JB Application power system

Application #2 Power System

DC Circuit Breakers are essential for safe and reliable power systems, especially in solar energy. These breakers detect and isolate faults, protecting PV panels from overcurrent conditions and maximizing system efficiency.

DC Circuit Breaker JB Application home house

Application #3 Home

DC Breakers are an essential safety feature for home electrical systems. These breakers protect against overcurrent conditions that can lead to electrical fires and equipment damage. In addition, they can help homeowners optimize energy usage by monitoring and controlling the flow of electricity.

DC Circuit Breaker JB Application office building

Application #4 Office Building

DC Breakers are commonly used in office buildings for a variety of applications, such as protecting electrical panels and equipment, controlling lighting and HVAC systems, and managing emergency power systems. They are also a crucial component of renewable energy systems, such as solar panels and wind turbines.

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