HUM8 MCCB Breaker – 10A to 1250A

HUM8 MCCB Breaker – Electronic Protection, Four Breaking Levels, Up to 125kA

When a standard thermal-magnetic MCCB breaker does not have sufficient adjustability or fault withstanding, HUYU Electric’s HUM8 provides a solution. The HUM8 has a total amperage range of 10A through 1250A with nine frames, operates at 690V AC, and uses an intelligent electronic trip device to provide precise, programmable protection. There are 4 break levels, S (Standard), C (Basic), H (High), and U (Ultra-high) that are rated from 30kA to 125kA Icu at 400V; therefore, it can be used to protect branch circuits all the way up to protection of major incomer.

Unlike typical molded case breakers, the HUM8’s electronic trip unit provides adjustable long-time, short-time, instantaneous, and earth-fault settings, plus short-time withstand current Icw up to 20kA on the 1250A frame for full selectivity. The eco-friendly design reduces material use without compromising performance or the 20,000-operation mechanical life on smaller frames. Buyers currently sourcing MCCB breakers from Schneider (Compact NSX with Micrologic), ABB (Tmax), Eaton, or Siemens can benefit from HUYU Electric’s factory-direct OEM/ODM pricing, private labeling options, and full IEC 60947-2 documentation.

Breaking Levels & Frame Sizes – S / C / H / U, 10A to 1250A

Electronic Trip Unit & Eco-Friendly Design

Unlike standard thermal-magnetic breakers that use fixed bimetallic and magnetic elements that cannot be altered or adjusted after manufacture, HUM8’s intelligent electronic release allows for post-installation adjustment of long time pickup, short time pickup and delay, instantaneous pickup, and earth fault settings. Thus, you can adjust the precise load and coordination requirements of the exact same molded-case circuit breaker thereby eliminating nuisance tripping, while still providing complete selectivity. The environmentally friendly design also uses fewer raw materials while delivering full short-circuit performance and mechanical endurance — a key consideration for projects needing adherence to green procurement criteria.

OEM / ODM Electronic MCCB Breakers for Selective Protection

Buyer’s Guide

How to Choose an Electronic MCCB Breaker – Level, Icw & Selectivity

A practical guide to selecting the correct performance level and trip unit for the HUM8 MCCB.

1. S, C, H, or U Breaking Level?

S (Standard) suits general distribution circuits with moderate fault current. C (Basic) covers branch circuits where cost is the priority. H (High) provides 85kA Icu for circuits closer to the transformer. U (Ultra-high) delivers 125kA Icu — the highest level available in this MCCB breaker family — making it suitable for main incomers and heavy industrial applications where fault current is highest. Always select the level based on the calculated prospective fault current at the point of installation.

2. Electronic Trip – Why Programmability Matters

The HUM8’s electronic trip unit allows field adjustment of long-time pickup (overload), short-time pickup and delay (selective short circuit), instantaneous pickup (direct short circuit), and ground fault. This adjustability means the same breaker can be optimised for different load types and coordination requirements without replacing the trip unit. For installations where loads change over time — such as industrial plants with expanding production lines — this flexibility avoids the cost of replacing fixed-setting thermal-magnetic breakers.

3. Icw and Selectivity

Short-time withstand current (Icw) is the current the breaker can carry for a defined period (1 second for the HUM8) without tripping. This is critical for selective coordination: when a downstream breaker clears a fault, the upstream breaker must hold through the fault current without tripping. The HUM8-1250’s 20kA Icw enables full selectivity with downstream breakers — the main incomer does not trip on a branch fault, minimising downtime to the affected circuit only.

4. Choosing the Right Frame Size

The HUM8 spans 63A to 1250A. For branch circuits, select the 63A–160A frames. For sub-mains and industrial feeders, the 250A–400A frames offer the best balance of rating and footprint. For main incomers, the 630A–1250A frames provide the required capacity with H or U breaking levels. The 1250A frame with 20kA Icw and S-level protection is specifically designed for main incomer duty where selective coordination is essential.

Frequently Asked Questions

What is an electrical MCCB?

An electrical MCCB — Molded Case Circuit Breaker — is an overcurrent protection device used in power distribution systems. It protects circuits against overload and short circuit, and can provide additional functions such as undervoltage tripping, motor operation, and earth fault protection. MCCBs cover a current range from approximately 10A to 1600A, sitting between miniature circuit breakers (MCBs) and air circuit breakers (ACBs) in the protection hierarchy. The HUM8 is an electrical MCCB with an electronic trip unit and breaking capacity up to 125kA.

What is an MCCB vs MCB?

An MCB is a compact, DIN-rail-mounted breaker rated up to 63A, used for protecting final circuits like lighting and sockets. An MCCB is larger, rated from 10A to 1600A, and designed for higher fault currents. MCCBs have higher breaking capacities (up to 125kA vs 6–10kA for MCBs), can include adjustable electronic trip units for programmable protection, and are available in fixed and plug-in configurations for branch circuits, feeders, and main incomers. The HUM8 is an MCCB; use it where an MCB would be undersized or where adjustable protection is needed.

What’s the difference between MCCB and RCCB?

An MCCB protects against overcurrent — too much current flowing due to overload or short circuit. An RCCB protects against earth leakage — current escaping to ground, potentially through a person. They serve different safety functions. Some MCCBs can be equipped with an earth leakage module to combine both overcurrent and leakage protection. The HUM8 is an MCCB; for circuits where earth leakage detection is also required, pair it with an RCCB or specify the electronic trip unit version with earth fault protection.

What is the difference between a power circuit breaker and a MCCB?

A power circuit breaker — typically an air circuit breaker (ACB) — is a larger, open-frame device rated from 630A to 6300A, used for main incomers and large feeders. It often includes withdrawable configurations, comprehensive communication, and extensive programmability. An MCCB is a moulded case device rated up to 1600A. The key differences: ACBs handle higher continuous currents and have higher short-time withstand (Icw) for cascaded selectivity; MCCBs are more compact and economical for branch and mid-range applications. The HUM8 bridges some of this gap: with Icu up to 125kA and Icw up to 20kA, it covers applications that traditionally required an ACB.