Search
DC MCB for Solar PV String Protection | 250V-1200V DC | CE Certified
Trustable Circuit Breaker Manufacturer
KRIPAL manufactures DC miniature circuit breakers (DC MCBs) specifically engineered for photovoltaic string protection in solar arrays and battery energy storage systems. Available in rated voltages from 250V DC to 1200V DC and current ratings from 1A to 63A, the UKB7Z series features a permanent magnet arc extinguishing system that achieves 6kA DC breaking capacity with no polarity restriction, allowing both top and bottom feed connections for installation flexibility in combiner boxes and inverter DC disconnects. Certified to IEC/EN 60947-2 and UL 489B for North American markets, KRIPAL DC MCBs are non-polarized design with a compact modular footprint supporting DIN-rail mounting in standard 18mm per pole width, with 1P, 2P, 3P and 4P configurations available from factory stock.
Get A Quote
UKB7Z DC MCB 1P 63A 250V DC Mini Circuit Breaker 6kA
UKB7Z miniature circuit breaker provides advanced electrical protection for DC systems with a rated voltage up to 1000V and a rated current up to 63A.
Ask a Quote
UKB7Z 2P 63A 500V DC Mini Circuit Breaker for PV solar DC MCB CE certified
UKB7Z miniature circuit breaker provides advanced electrical protection for DC systems with a rated voltage up to 1000V and a rated current up to 63A.
Ask a Quote
UKB8Z DC Mini Circuit Breaker 1Pole 63A 300V DC MCB 6kA
The UKB8Z-63 high-breaking-capacity DC miniature circuit breaker is designed for use in photovoltaic (PV) DC systems.
Ask a Quote
UKB8Z DC Miniature Circuit Breaker 6kA 4P 63A 1200V DC MCB
The UKB8Z-63 high-breaking-capacity DC miniature circuit breaker is designed for use in photovoltaic (PV) DC systems.
Ask a QuoteDC MCB Selection Guide for PV Systems and Battery Storage
A DC miniature circuit breaker protects photovoltaic strings and DC branch circuits against overload and short-circuit conditions. DC current has no natural zero-crossing point, which means the arc generated during fault interruption is continuous and harder to extinguish than AC arcs. KRIPAL DC MCBs address this with a permanent magnet arc chamber that forces the arc into a segmented arc chute, splitting and cooling the arc plasma until extinction. This selection guide covers voltage class, pole count, breaking capacity and curve selection to help you specify the correct DC MCB for your photovoltaic installation.
UKB7Z DC MCB Series Technical Specifications
Rated Voltage and System Compatibility
UKB7Z DC MCBs cover rated operational voltages of 250V, 500V, 750V, 1000V and 1200V DC to match the most common PV string architectures. A single-pole 250V unit protects one string in residential rooftop arrays with microinverters, while a 4P 1200V unit handles utility-scale combiner box outputs. The non-polarized design eliminates the risk of reverse polarity arc failure common with polarized breakers, supporting both source-side and load-side fault clearing regardless of current direction.
Breaking Capacity and DC Arc Management
The UKB7Z achieves 6kA DC breaking capacity (Icu) through a permanent magnet blowout system combined with a 13-plate segmented arc chute. Each arc chute plate is made of low-carbon steel with a zinc coating to resist DC arc erosion over the product lifetime. The magnet assembly is oriented so that arc force direction is independent of current polarity, maintaining consistent interruption performance at any rated voltage within the series range. This arc management system also keeps let-through energy (I squared t) low, reducing thermal stress on upstream DC cables and connectors.
Trip Curve Selection and Coordination
UKB7Z DC MCBs are available in B-curve (3-5 In instantaneous trip, for purely resistive loads like DC heating elements) and C-curve (5-10 In, for inductive-capacitive loads including inverter DC inputs and battery charge controllers). For PV string protection, the C-curve is recommended because PV panel short-circuit current (Isc) is typically only 10-25% above rated operating current, and the magnetic trip threshold must be high enough to avoid nuisance tripping during cloud-edge irradiance transients but low enough to clear bolted faults within the string cable ampacity limit.
Installation and Certifications
Each UKB7Z pole occupies 18mm of DIN-rail width (standard modular format), with multi-pole units ganged via internal pin linkage for simultaneous switching of all poles in a single body. The IP20 finger-safe housing accepts both pin and fork type busbars from the top or bottom terminals. All units carry CE marking and are manufactured in accordance with IEC/EN 60947-2 Annex P for DC applications, with UL 489B recognized versions available for North American PV installations requiring AHJ approval. Individual carton packaging with QR-coded test reports is available for projects requiring full traceability documentation.
Specify DC MCBs for Your PV Project
- Datasheet and Coordination Tables: Request voltage-specific I squared t curves and upstream/downstream selectivity tables for your combiner box design.
- UL 489B Compliance Package: Obtain AHJ-ready certification documents including UL file numbers, factory test reports and component recognition certificates.
- Volume OEM Pricing: Contact our solar components team for container-level pricing on UKB7Z breakers with your choice of busbar accessories and terminal shrouds.
Protecting Solar PV Strings in Residential, Commercial and Utility Installations
KRIPAL DC MCBs provide string-level overcurrent protection across the full spectrum of photovoltaic installations, from residential rooftop systems to utility-scale solar farms. The non-polarized design and 6kA breaking capacity make these breakers suitable for any DC circuit topology found in modern solar and battery storage architectures.
Residential Rooftop PV String Protection
In single-phase residential installations with 3-8 kW string inverters, UKB7Z-250V 2P DC MCBs protect individual PV strings between the rooftop junction box and the inverter DC isolator. The compact 36mm width for a 2P unit fits standard residential combiner enclosures, and the non-polarized design eliminates installation errors when connecting to transformerless inverters where DC polarity can be ambiguous during low-light conditions.
Commercial Rooftop and Ground-Mount Arrays
Commercial installations (30-500 kW) with multiple string combiners use UKB7Z-750V or 1000V 2P and 3P breakers at the combiner box output. The ganged multi-pole design simultaneously isolates both positive and negative conductors of a bipolar array configuration, meeting IEC 60364-7-712 requirements for all-pole disconnection of PV source circuits. The 6kA breaking capacity handles the combined short-circuit contribution of up to 20 parallel strings without coordination gaps.
Utility-Scale Solar Farm DC Combiner Boxes
Utility-scale PV plants (1 MW and above) deploy UKB7Z-1200V 4P DC MCBs in central combiner boxes to protect aggregated string feeders before the inverter DC bus. At these system voltages, the permanent magnet arc chute provides consistent interruption of fault currents up to 6kA without voltage-dependent derating. The non-polarized design is critical in large arrays where reverse current from adjacent healthy strings can flow through a faulted string from the opposite direction than normal operating current.
Battery Energy Storage DC Branch Protection
Lithium-ion battery racks in C&I and utility storage systems use DC MCBs rated at 500V to 1000V to protect individual battery module strings against internal cell short circuits and external cable faults. The UKB7Z C-curve provides adequate inrush delay for BMS pre-charge circuits while still clearing bolted faults within the battery cable thermal damage curve. The DIN-rail form factor integrates directly into standard battery cabinet control panels alongside the BMS master controller and contactor-based isolation switches.
DC Fast Charging Station Auxiliary Circuits
EV DC fast chargers (50-350 kW) incorporate UKB7Z DC MCBs on auxiliary DC power supplies feeding the charger controller, cooling fans, communication modules and payment terminal. These auxiliary circuits typically operate at 24V or 48V DC and require compact protection devices that fit within the charger enclosure. The 250V-rated units provide ample voltage headroom for any auxiliary DC bus, and the screw-clamp terminals accept the fine-stranded control wiring commonly used in charger internal harnessing.
Engineer Your DC Circuit Protection
- Selectivity Study Support: Send us your single-line diagram and we return a complete protection coordination table with recommended UKB7Z ratings and settings.
- Sample Testing Program: Request evaluation samples for your combiner box prototype with full type-test certification data for AHJ submission.
- Custom Busbar Solutions: Need comb-shaped or fork busbars for multi-pole DC MCB assemblies? We supply UL-listed busbar sets matched to your panel layout.
KRIPAL DC MCB Manufacturing: Precision Engineering for Solar Applications
KRIPAL DC miniature circuit breakers are manufactured in a dedicated solar protection production cell in Zhejiang, where permanent magnet arc chambers, precision-calibrated thermal-magnetic trip units, and silver-graphite contacts are assembled and tested in-house, ensuring consistent DC interruption performance for global PV system integrators and solar EPC contractors.
Permanent Magnet Arc Extinguishing Chamber Assembly
Each DC MCB is fitted with a permanent magnet arc chamber that forces the DC arc into a splitter stack for rapid extinguishing. The magnet orientation and arc runner geometry are verified per production lot to maintain consistent 6kA/10kA DC breaking capacity at rated voltages up to 1200V.
Thermal-Magnetic Trip Unit Calibration
Bimetal strips are individually calibrated on automated test benches that simulate overload current profiles defined in IEC 60947-2. Cold-state calibration data is recorded per unit, with trip time tolerances held within plus or minus 10 percent of the published time-current curve across the full 1A to 63A range.
Non-Polarized Design Verification
Each DC MCB production batch undergoes polarity-independent short-circuit testing in both current directions. The symmetrical contact and arc chamber design eliminates installation errors in PV string wiring where polarity reversal can occur during commissioning or maintenance.
Environmental Stress Screening for PV Applications
Completed DC MCBs are subjected to thermal cycling from minus 25 to plus 70 degrees Celsius in environmental chambers before final electrical test. Units destined for high-altitude PV installations receive additional dielectric testing at reduced air pressure simulating 4000 m altitude conditions.
Distributor Stock Holding Programs for DC MCBs
KRIPAL supports distributor inventory programs with agreed stock levels for standard DC MCB models. Shipments are planned based on demand data, with scheduled replenishment to maintain stable supply and consistent fill rates.
Private Label and OEM Branding for DC MCBs
Laser-marked part numbers aligned with your catalog, OEM-branded packaging, and customized multilingual instruction sheets are available. Unbranded supply is provided upon request for private label production of DC MCBs.
Multi-Region Certification and Compliance Support
CE, UKCA, and IEC 60947-2 Annex P compliance documentation is provided according to target export markets. Technical documentation files are maintained and updated in line with evolving regulatory requirements, supporting solar PV system conformity assessments.
Direct Technical Access to KRIPAL Production Engineers
Your technical team communicates with the engineers who designed and tested your DC MCBs, not a distributor’s sales engineer reading from a catalog. Application questions receive answers within 24 hours during China business hours.
Frequently Asked Questions
Explore FAQ >Direct from Manufacturer
How Can We Assist You?
Tell us a bit more so we can route your request to the right engineer. Get factory-direct pricing and custom specifications within 24 hours.
