Description
CBI UL489B rated circuit breaker.
- 20 Amps
- 150V DC
- Unpolarized (source wires can be fed from the top or bottom of breaker)
- UL489B
UL 489B is a safety standard developed by Underwriters Laboratories (UL), specifically tailored to address DC circuit breakers used in photovoltaic (PV) systems and similar applications. It is a subset of the broader UL 489 standard, which applies to molded case circuit breakers in general, including AC and DC systems.
Key Features of UL 489B
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DC System Specificity:
- UL 489B focuses on DC circuit breakers, which must handle continuous direct current without the zero-crossing points present in AC systems. This makes interrupting DC arcs more challenging.
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Application in Photovoltaic Systems:
- It is commonly used in solar power systems where high-voltage DC is present, such as between solar panels, charge controllers, and inverters.
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Testing for High Voltage and Low Current:
- The standard includes rigorous testing procedures to ensure that circuit breakers can safely handle DC arcs, high voltages (up to 1500 VDC), and often lower fault currents.
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High Interrupting Ratings:
- Circuit breakers compliant with UL 489B have high interrupting capacities to deal with the potential energy in large PV systems.
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Specific Environmental Testing:
- Products are tested for temperature extremes, humidity, and long-term exposure to conditions typical of outdoor or solar installations.
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Backfeed Protection:
- Ensures breakers can prevent damage from backfed currents, common in systems where energy may flow from batteries or inverters.
Why UL 489B Matters
- Safety Assurance: Compliance guarantees that a circuit breaker can safely and reliably interrupt faults in high-voltage DC circuits.
- Regulatory Compliance: Many local and international electrical codes require UL 489B-certified equipment in PV installations.
- Enhanced Reliability: Equipment built to this standard is more reliable under the unique stresses of DC systems.
UL 489B certification ensures that the product is suitable for protecting people, equipment, and systems in high-performance DC applications like solar power installations.
