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ELCB MCCB with Earth Leakage Protection | 16A-630A | Adjustable 30mA-30A
Factory-Built ELCB & MCCB Solutions for Professional Protection
KRIPAL manufactures earth leakage molded case circuit breakers (ELCB MCCBs) in the UKM1EL series, combining overcurrent protection (thermal-magnetic trip unit) with adjustable earth leakage protection in a single integrated device. Available in frame sizes from 100AF to 630AF with rated currents from 16A to 630A and breaking capacities up to 65kA at 400V AC, the UKM1EL features an electronic earth leakage module with adjustable sensitivity from 0.03A to 3A and adjustable time delay from 0 to 1 second. The module connects to an external zero-sequence current transformer (ZCT) mounted around the three phases and neutral conductors, detecting the vector sum of currents which is zero in a healthy circuit and non-zero when current leaks to earth. An internal test button injects a calibrated residual current to verify the earth leakage trip function without external test equipment. The UKM1EL provides the selective coordination capability needed for cascaded earth leakage schemes, where the upstream device has a higher sensitivity and time delay to allow downstream RCCBs or RCBOs to clear local faults without tripping the main device. Compliant with IEC 60947-2 Annex B for circuit breakers with integral earth leakage protection, KRIPAL ELCB MCCBs are specified for main incoming protection, sub-main protection and equipment-level earth leakage protection in industrial and commercial installations.
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An earth leakage MCCB (also called an ELCB or CBR with integral residual current protection) combines the overcurrent and short-circuit protection of a standard MCCB with earth leakage detection using an external current transformer. Unlike an RCCB which only provides earth leakage protection, an ELCB MCCB provides all three protection functions (overload, short-circuit, earth leakage) in one device, reducing the number of components in the switchboard and simplifying the protection coordination scheme. The electronic earth leakage module allows field adjustment of sensitivity and time delay, enabling selective coordination with downstream earth leakage devices so that a local earth fault clears the nearest downstream device without tripping the upstream ELCB MCCB. This selection guide covers sensitivity, time delay, ZCT selection and coordination with downstream devices.
UKM1EL ELCB MCCB Series Technical Specifications
Adjustable Earth Leakage Sensitivity Selection
The UKM1EL earth leakage sensitivity (I delta n) is adjustable in steps from 0.03A to 3A, selected according to the protection objective. 30mA provides personal protection against electric shock, suitable for circuits where direct contact is possible. 100mA provides fire protection, suitable for distribution circuits in buildings with combustible construction materials. 300mA and 500mA provide equipment protection and are used as upstream selectivity devices that coordinate with 30mA downstream RCCBs. 1A and 3A are used for large installations with inherently high standing earth leakage (long cable runs, multiple machines with EMI filters) where lower sensitivities would cause nuisance tripping. The sensitivity is set via a rotary switch on the electronic module, and the setting is visible through a window on the MCCB front cover.
Time Delay and Selective Coordination
The UKM1EL time delay is adjustable from 0 seconds (instantaneous) to 1 second, enabling selective coordination with downstream earth leakage devices. The delay is implemented as a definite-time characteristic: when the earth leakage current exceeds the set sensitivity, the timer starts, and the MCCB trips after the set delay if the leakage persists. For a typical cascaded scheme with a 1A 0.5 second UKM1EL at the main board and 30mA instantaneous RCBOs on final circuits, the time delay ensures that a 30mA fault on a final circuit trips the RCBO within 40ms, long before the 0.5 second delay expires on the upstream ELCB. This achieves discrimination by both current magnitude (the 1A ELCB does not respond to a 30mA fault) and time (a 1A fault that could trip both devices clears the downstream device first).
Zero-Sequence Current Transformer Selection
The UKM1EL requires an external ZCT (supplied separately or as a kit) that mounts around the three phases and neutral conductors. The ZCT internal diameter must accommodate the total cross-sectional area of all four conductors including insulation. For a 400A MCCB with 185 sq mm conductors, a ZCT with a 110mm internal diameter is required. The ZCT is a toroidal core with a secondary winding that produces a voltage proportional to the vector sum of the primary currents. The ZCT must be mounted with the conductors centered in the aperture and secured against vibration, as conductor movement can induce false residual current signals. KRIPAL supplies matching ZCTs for each UKM1EL frame size, and the ZCT secondary cable (shielded twisted pair, maximum length 5 meters) connects to the MCCB’s electronic module via a dedicated terminal.
Earth Leakage Test and Monitoring
The UKM1EL includes a front-panel test button that injects a calibrated residual current into the ZCT secondary winding, simulating an earth fault and verifying that the electronic module detects the current and trips the MCCB within the set time delay. The test should be performed every 6 months per IEC 60364-6 and the result recorded in the installation’s maintenance log. An optional earth leakage current display module (panel-mounted) shows the real-time earth leakage current measured by the ZCT, allowing the maintenance electrician to monitor the installation’s standing leakage current and identify circuits with increasing leakage (indicating degrading insulation) before the leakage reaches the trip threshold. The display module also logs the maximum leakage current since the last reset, useful for investigating intermittent earth faults that do not persist long enough to trip the MCCB.
Specify Earth Leakage Protection for Your Installation
- Selectivity Design: Our engineers design a cascaded earth leakage scheme with UKM1EL and downstream RCCB/RCBO settings verified for discrimination.
- ZCT Sizing: Provide your cable sizes and we specify the correct ZCT diameter and mounting arrangement.
- OEM Supply: Source UKM1EL MCCBs with matching ZCTs pre-assembled for your switchboard production.
Earth Leakage Protection for Critical Environments
KRIPAL UKM1EL ELCB MCCBs provide combined overcurrent and earth leakage protection at the main and sub-main distribution level in industrial, commercial and infrastructure installations. The adjustable sensitivity and time delay enable selective coordination with downstream earth leakage devices, ensuring that an earth fault on one final circuit does not interrupt power to healthy circuits fed from the same distribution board.
Industrial Main Switchboard Incoming Earth Leakage Protection
A factory main switchboard uses a UKM1EL 630A 3P ELCB MCCB as the incoming device, with the earth leakage set to 1A and a time delay of 0.3 seconds. The ZCT is installed around the three incoming phase conductors (the neutral is solidly earthed at the transformer and not switched). The 1A setting provides equipment and fire protection for the main busbar and incoming cables, while the 0.3 second delay provides selectivity with the 300mA instantaneous RCCBs installed on the outgoing feeder circuits. The earth leakage display module is mounted on the switchboard front panel, allowing the maintenance electrician to check the standing leakage current during the weekly switchboard inspection and identify any circuit with increasing leakage before it reaches the trip threshold.
Commercial Building Sub-Main Earth Leakage Protection
A commercial office building’s floor distribution board is fed by a UKM1EL 250A 4P ELCB MCCB with the earth leakage set to 300mA and a time delay of 0.1 seconds. This provides fire protection for the floor distribution circuits (long cable runs through ceiling voids and riser shafts where an earth leakage fault could ignite combustible building materials) while coordinating with the 30mA RCBOs on the floor’s final circuits. The 300mA setting is above the expected standing leakage from the floor’s electronic equipment (approximately 50-80mA for 80 workstations with desktop computers, LED lighting and printers), avoiding nuisance tripping during normal operation.
Water Treatment Plant Motor Feeder Protection
A water treatment plant’s submersible pump feeder uses a UKM1EL 160A 3P ELCB MCCB with the earth leakage set to 100mA instantaneous. Submersible pumps are particularly vulnerable to earth leakage faults as the pump motor’s winding insulation degrades over time due to water ingress through worn mechanical seals. The 100mA setting provides early detection of insulation degradation, tripping the pump feeder before a full phase-to-earth short-circuit develops and causes extensive motor damage. The earth leakage trip is signaled to the plant SCADA system via the MCCB’s alarm contact, generating an automatic work order for the maintenance team to inspect the pump before the fault escalates.
Construction Site Temporary Supply Protection
A construction site’s temporary supply pillar uses a UKM1EL 250A 4P ELCB MCCB with the earth leakage set to 300mA and a time delay of 0.1 seconds as the main incoming device. Construction sites present a high risk of cable damage (cables run across the ground and are subject to vehicle traffic, excavation and falling objects), and the 300mA earth leakage protection provides an additional layer of safety beyond the 30mA RCDs on individual socket outlet circuits. The ELCB MCCB provides backup protection if a cable is damaged between the supply pillar and the site distribution board (before the RCD), a section of the installation that is typically only protected by the overcurrent function of a standard MCCB.
Agricultural Building Main Supply Protection
Agricultural buildings housing livestock use a UKM1EL 160A 4P ELCB MCCB with the earth leakage set to 100mA instantaneous as the main incoming device. Livestock are particularly susceptible to electric shock (lower body impedance due to contact with wet concrete floors, and a ventricular fibrillation threshold as low as 20mA for cattle), making earth leakage protection critical. The 100mA setting is a compromise between providing the lowest practical protection level and avoiding nuisance tripping from the inherently high standing leakage in agricultural environments (moisture in junction boxes, long cable runs in high-humidity buildings, and electric fence energizers that deliberately couple current to earth).
Specify Earth Leakage Protection for Your Power System
- Protection Study: Our engineers design a complete earth leakage protection scheme with UKM1EL settings and ZCT specifications.
- Discrimination Verification: Request time-current coordination tables for your cascaded ELCB and RCD scheme.
- OEM Supply: Source UKM1EL MCCBs complete with ZCTs and display modules for your switchboard production.
Integrated Testing and Supply Chain
KRIPAL ELCB MCCBs integrate earth leakage protection with thermal-magnetic overcurrent protection in a single molded case device. Manufacturing combines the MCCB assembly line with a dedicated earth leakage module production cell where the summation current transformer and electronic trip relay are assembled, calibrated, and tested for global earth fault protection applications.
Earth Leakage Detection Module Assembly
The earth leakage module incorporates a summation current transformer with a toroidal core wound to precision secondary turns, connected to an electronic trip PCB. The module is assembled in an ESD-protected production cell where the PCB is conformally coated for environmental protection after functional test. Sensitivity is factory-set to the rated residual operating current (adjustable 30mA to 30A).
Combined Overcurrent and Earth Leakage Calibration
Each ELCB MCCB undergoes combined calibration: the thermal-magnetic trip unit is calibrated for overcurrent protection per IEC 60947-2, while the earth leakage module is calibrated for residual current tripping per IEC 60947-2 Annex B. Trip time at rated I-delta-n is verified within 300ms (adjustable time delay settings available).
Integrated Test Button and Trip Indication
Every ELCB incorporates a front-panel test button that injects a test current through the summation transformer to verify earth leakage trip function. The mechanical trip indicator (push-to-trip flag) is verified for positive indication. A volt-free alarm contact option provides remote earth fault signaling for building management system integration.
Insulation Coordination and Dielectric Testing
ELCB MCCBs undergo dielectric withstand testing at 2500V between all main poles, between poles and the earth leakage module, and across open contacts. The electronic trip module is surge-tested per IEC 61000-4-5 to verify immunity to transient overvoltages on the supply side that could cause nuisance tripping.
Distributor Stock Holding Programs for ELCB MCCBs
KRIPAL supports distributor inventory programs with agreed stock levels for standard ELCB MCCB models. Adjustable sensitivity and time delay versions are available, with shipments planned based on demand data and scheduled replenishment.
Private Label and OEM Branding for ELCB MCCBs
Laser-marked part numbers aligned with your catalog, OEM-branded packaging, and customized instruction sheets are available. Unbranded supply is provided upon request for private label production of ELCB MCCBs.
Multi-Region Certification and Compliance Support
CE, UKCA, and IEC 60947-2 Annex B compliance documentation is provided according to target export markets. Technical documentation files are maintained and updated in line with evolving earth fault protection regulatory requirements.
Direct Technical Access to KRIPAL Production Engineers
Your technical team communicates with the engineers who designed and calibrated your ELCB MCCBs, not a distributor’s sales engineer reading from a catalog. Application questions including earth leakage discrimination and zone selectivity receive answers within 24 hours during China business hours.
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