Search
MCB Accessories: Auxiliary Contacts Shunt Trips Busbars | DIN Rail Compatible
KRIPAL Miniature Circuit Breaker Accessories
KRIPAL manufactures a comprehensive range of MCB accessories for the UKB5, UKB7, UKNT50 and UKBH series miniature circuit breakers, enabling extended functionality beyond basic overcurrent protection. The accessory range includes auxiliary contacts (1NO+1NC or 2CO changeover) for remote status signaling, shunt trip releases for remote tripping from a fire alarm panel or emergency stop button, undervoltage releases that trip the MCB when the supply voltage drops below 70 percent of nominal (preventing automatic restart of motors after a power outage), busbars in pin-type and fork-type configurations for rapid multi-pole installation, terminal shrouds and blanking plates for IP2X finger protection, and padlock devices for locking the MCB in the OFF position during maintenance. All accessories clip onto the side or front of the MCB without tools, and are fully compatible across the entire KRIPAL MCB range. CE and UKCA marked, these accessories expand the MCB’s role from a simple overcurrent device to a functional circuit protection and control module integrated with building management and safety systems.
Get A Quote
UKZ7-NHK Circuit Breaker Auxiliary Contact 250VAC Side-Mount
The UKZ7-NHK is a high-performance, side-mounting auxiliary contact attachment designed for circuit breakers.
Ask a QuoteMCB Accessory Guide: Remote Control and Status Monitoring
MCB accessories extend the basic overcurrent protection function into a complete circuit management solution. An auxiliary contact signals the MCB status to a PLC or building management system, enabling remote monitoring of circuit health. A shunt trip release allows the MCB to be tripped by an external signal (fire alarm, emergency stop, process interlock), integrating circuit protection into the building’s safety systems. An undervoltage release protects motors and equipment from automatic restart after a power outage. Busbars simplify multi-pole installation by replacing individual wire jumpers with a single pre-formed conductor. This selection guide covers each accessory type, its function, and its integration with the MCB and the wider electrical installation.
MCB Accessories Technical Specifications
Auxiliary Contacts and Status Signaling
The auxiliary contact module clips onto the side of the MCB and is mechanically driven by the MCB’s toggle mechanism, providing a positive indication of the actual contact position (not just the handle position). The changeover contact (1NO+1NC) is rated at 250V AC 3A or 24V DC 1A, suitable for connection to PLC digital inputs, building management system I/O modules or indicator lamps. A red indicator on the auxiliary contact housing shows the contact state at a glance. Multiple auxiliary contacts can be stacked on the same MCB (up to 2 modules on the left side and 2 on the right side of a 1P MCB), allowing simultaneous signaling to multiple systems.
Shunt Trip and Undervoltage Releases
The shunt trip release is an electromagnetic coil that mechanically trips the MCB when energized by an external voltage (typically 24V DC or 230V AC). It is wired to a fire alarm panel’s auxiliary output, an emergency stop button, or a process safety interlock, providing automatic circuit disconnection on a safety event. The undervoltage release (UVR) is a coil that holds the MCB closed when the supply voltage is above 85 percent of nominal and trips the MCB when the voltage drops below 70 percent. The UVR is used for motor circuits where automatic restart after a power outage could cause injury to personnel working on the driven machinery, or for lighting circuits in windowless rooms where sudden darkness could create a hazard during a brownout.
Busbar Systems for Rapid Installation
KRIPAL MCB busbars are manufactured from tin-plated copper with pre-punched pins at 18mm pitch for direct insertion into the MCB’s busbar-compatible bottom terminal. Pin-type busbars are used with MCBs that have a dedicated busbar terminal (the pin inserts vertically), while fork-type busbars are used with MCBs that accept the busbar under the standard screw terminal (the fork slides under the screw clamp). Busbars are available in 1P (single-phase line), 2P (L+N), 3P (L1+L2+L3) and 4P (L1+L2+L3+N) configurations, with lengths to suit consumer units from 4 to 24 ways. The busbar is supplied with insulating end caps and a snap-on cover that provides IP2X finger protection. A busbar system reduces MCB installation time by approximately 80 percent compared to individual wire jumpers.
Padlock Devices and Safety Lockout
The MCB padlock device clamps onto the MCB toggle, locking it in the OFF position and accepting a padlock with a shackle diameter up to 4mm. This provides a local lockout-tagout point for individual circuit isolation during maintenance, without needing to lock out the entire distribution board. For motor circuits and equipment feeders where maintenance personnel must isolate a specific machine, the MCB padlock provides a convenient isolation point adjacent to the equipment. The padlock device is compatible with all KRIPAL MCB frame sizes and can be retrofitted to existing installations without disconnecting the MCB or removing it from the DIN-rail.
Extend Your MCB Functionality
- Accessory Compatibility Check: Tell us your MCB series and the required accessory functions, and we confirm compatibility and provide part numbers.
- Panel Integration Support: Request wiring diagrams for shunt trip and auxiliary contact integration with common fire alarm and BMS panels.
- OEM Bulk Supply: Order accessories in bulk alongside MCBs for your panel building operation.
Smart Distribution and Safety Interlock Applications
KRIPAL MCB accessories extend the basic overcurrent protection device into a connected, monitored and remotely controllable circuit management module. From the auxiliary contact on a critical server room circuit to the shunt trip on a kitchen extraction fan interlocked with the fire suppression system, these accessories integrate the MCB into the wider building safety and automation infrastructure.
Fire Alarm Integration with Shunt Trip MCBs
Commercial kitchen ventilation systems use MCBs fitted with shunt trip releases, wired to the kitchen fire suppression system (Ansul or equivalent). When the fire suppression system activates, it sends a 24V DC signal to the shunt trip coils on the MCBs feeding the kitchen extraction fans, cooking appliances and gas solenoid valve, disconnecting all power and fuel supplies to the cooking area simultaneously. The shunt trip must operate within 50ms of receiving the signal to prevent the extraction fan from continuing to feed oxygen to a cooking oil fire. The auxiliary contact on the same MCB signals the fire alarm panel that the kitchen power has been successfully isolated.
BMS Circuit Status Monitoring with Auxiliary Contacts
A commercial building’s critical circuits (server room UPS input, security system supply, fire alarm panel supply) use MCBs with auxiliary contacts wired to the building management system (BMS) digital inputs. The BMS monitors the status of each critical circuit in real time and generates an alarm if any MCB trips, allowing the facilities manager to dispatch an electrician before the UPS battery depletes and the servers shut down. The auxiliary contact is mechanically driven by the MCB toggle, so it reports the actual contact position even if the toggle is manually switched to OFF by a maintenance technician.
Motor Restart Prevention with Undervoltage Release
Industrial motor circuits driving conveyors, mixers and machine tools use MCBs with undervoltage releases. If the supply voltage drops below 70 percent of nominal (during a brownout or a supply changeover from utility to generator), the UVR trips the MCB, preventing the motor from automatically restarting when the voltage recovers. This is a safety requirement per IEC 60204-1 for machine electrical equipment, because an unexpected motor restart could injure an operator who is clearing a jam or performing a tool change, assuming the machine is de-energized after the power interruption. The UVR must be manually reset by the operator after confirming the machine is clear.
Distribution Board Installation Efficiency with Busbars
Panel builders and electrical contractors use KRIPAL busbars to install MCBs in consumer units and distribution boards with a single busbar per row, replacing individual wire jumpers between each MCB and the incoming supply. A 12-module consumer unit row that would require 24 individual conductor terminations (12 MCB line terminals plus 12 supply side connections) is reduced to 2 terminations (the busbar ends) plus the 12 MCB busbar terminal insertions (which are push-fit, not screw-clamp). This reduces the unit’s wiring time, eliminates the risk of a misplaced jumper causing a cross-phase short-circuit, and produces a cleaner installation that is easier to inspect and test.
Equipment Maintenance Lockout with Padlock Devices
Maintenance technicians working on individual items of plant (pumps, fans, compressors) use the MCB padlock device to lock the equipment’s dedicated MCB in the OFF position, providing a local isolation point that does not require access to the main distribution board (which may be locked or in a different building). The padlock device is applied after the technician has switched the MCB to OFF and verified with a voltage tester that the equipment supply is de-energized. The technician retains the padlock key, satisfying the “personal lock” requirement of the site lockout-tagout procedure. The padlock device is bright red for visibility during a visual sweep of the distribution board before re-energization.
Specify MCB Accessories for Your Installation
- Accessory Selection Guide: Describe your functional requirements and we specify the correct accessories with wiring diagrams for integration.
- Panel Wiring Support: Request busbar cutting lengths and terminal torque specifications for your specific distribution board layout.
- OEM Bulk Supply: Order MCBs pre-fitted with accessories for JIT delivery to your panel assembly line.
KRIPAL MCB Accessory Manufacturing: Clip-On Intelligence
KRIPAL MCB accessories including auxiliary contacts, shunt trips, undervoltage releases, and busbar combs are manufactured in a dedicated accessories production cell where each component is assembled, functionally tested, and verified for mechanical compatibility with the full MCB product range. Accessories ship with installation instructions and terminal marking for global panel builder applications.
Auxiliary Contact and Signal Contact Assembly
Auxiliary contacts (OF) and signal contacts (SD) are assembled from silver-nickel contact elements in a miniature housing that clips directly onto the MCB body. Each assembled unit is tested for contact transition timing relative to the MCB main contacts, with make/break timing verified to meet specified advance/delay requirements for remote status monitoring.
Shunt Trip and Undervoltage Release Calibration
Shunt trip coils are wound and calibrated to operate within the specified voltage range (typically 70 to 110 percent of rated voltage). Undervoltage releases are calibrated to trip when voltage falls below 70 to 35 percent of rated and to prevent MCB closure below 85 percent. Each release mechanism is functionally tested across its operating voltage range.
Motor Operator and Remote Control Module Testing
Motor-driven remote operating mechanisms are assembled from a geared DC motor, limit switches, and manual override lever. Each motor operator undergoes a 500-cycle endurance test on the first article of each production batch, with subsequent units receiving a 50-cycle functional test verifying remote ON, OFF, and RESET operations.
Busbar Comb and Pin Compatibility Verification
Busbar combs and connecting pins are manufactured to precise pitch dimensions matching the MCB terminal spacing. Sample assemblies from each production lot are tested for insertion force, contact resistance at rated current, and short-circuit withstand in combination with MCBs at the rated conditional short-circuit current. Interoperability with all MCB frame sizes is verified.
Distributor Stock Holding Programs for MCB Accessories
KRIPAL supports distributor inventory programs with agreed stock levels for standard accessory models. Bulk packs of busbar combs, terminals, and common accessories are available with competitive pricing for volume distributors.
Private Label and OEM Branding for MCB Accessories
Neutral-packaged accessories with OEM part numbering and distributor-branded instruction sheets are available. KRIPAL supports the supply of accessories configured to match specific MCB product ranges for integrated distribution programs.
Multi-Region Certification and Compliance Support
CE, UKCA, and relevant IEC standard compliance documentation is provided for all accessory types according to target export markets. Technical documentation files are maintained and updated in line with evolving regulatory requirements.
Direct Technical Access to KRIPAL Production Engineers
Your technical team communicates with the engineers who designed and tested your MCB accessories, not a distributor’s sales engineer reading from a catalog. Application questions including accessory compatibility across product generations receive answers within 24 hours during China business hours.
Frequently Asked Questions
Explore FAQ >OF indicates the MCB toggle position (open/closed). SD indicates the MCB has tripped on overload or short circuit. An OF+SD combo provides both signals.
The shunt trip is a solenoid that mechanically trips the MCB when voltage is applied, typically activated by a fire alarm panel or emergency stop circuit.
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.
