AC Molded Case Trip Unit

FAQ

What Are the Different Types of Trip Units?

Thermal-Magnetic (T-M)

• Combines thermal (overload) and magnetic (short-circuit) protection
• Thermal element reacts with time delay to sustained overcurrent
• Magnetic element trips instantly under fault conditions
• Widely used in standard industrial and commercial applications

Solid-State (Electronic)

• Uses electronic sensors for precise current monitoring
• Offers adjustable protection settings and higher accuracy
• Supports advanced features like communication and metering
• The AC Molded Case Trip Unit in electronic form is ideal for complex systems

Magnetic Only

• Provides instantaneous protection against short circuits only
• No overload (thermal) protection included
• Commonly used for motor circuits with external overload relays

What Are the Key Adjustments on a Trip Unit?

Long-Time (LT / Thermal) Pickup

• Sets the current level for overload protection
• Determines when the breaker trips under sustained overcurrent
• Helps protect cables and equipment from overheating

Short-Time (ST) Pickup / Delay

• Provides short delay before tripping during fault conditions
• Allows coordination with downstream protective devices
• Reduces unnecessary system interruptions

Instantaneous Trip

• Triggers immediate breaker operation during severe short circuits
• No intentional delay for maximum protection speed
• The AC Molded Case Trip Unit ensures rapid fault clearance to protect equipment

Can I Use an AC Trip Unit for DC Applications?

• Generally, AC trip units are not recommended for DC systems
• DC circuits have different arc characteristics and require specialized designs
• Using AC-only devices in DC applications may lead to unsafe interruption
• Always verify manufacturer specifications before application

Are Trip Units Replaceable?

Thermal-Magnetic Units

• Typically fixed and integrated into the breaker body
• Replacement usually requires changing the entire MCCB
• Simple design ensures durability and low maintenance

Electronic Trip Units

• Often modular and replaceable depending on design
• Allows upgrades or maintenance without replacing the full breaker
• The AC Molded Case Trip Unit with electronic design offers greater flexibility

Why Choose Pugao (Plannter Electric)?

• Reliable Quality: Our AC Molded Case Trip Unit and other MCCBs undergo rigorous testing, including short-circuit breaking up to 200kA and insulation voltage up to 800V, ensuring stable performance in industrial applications.
• Strong Technical Support: Over 15 senior engineers with 10+ years of low-voltage product experience design and optimize products like the 4P Electronic Trip Unit for accurate protection and system reliability.
• Competitive Pricing: Direct factory supply reduces costs by 15–20% compared to similar international brands, without compromising quality.
• Flexible Production: Supports rated currents from 100A to 1600A and customizable configurations, meeting diverse industrial and commercial requirements.
• Responsive Service: Average response time to technical inquiries is under 24 hours, ensuring fast support during installation or maintenance.