Description
MERLIN GERIN
MASTERPACT
M12 H1
CIRCUIT BREAKER
UI: 1000V~ 50/60HZ
UE: 380/440V 480/690V
ICU: 65KA 65KA
ICS: 65KA 65KA
ICW: 65KA 0,5S
RATED CURRENT(A): 1250
SENSOR(A): 1250
UNDERVOLTAGE: 230V AC
The Merlin Gerin Masterpact M12 H1 is a heavy-duty air circuit breaker rated at 1250A, designed for high-demand electrical protection and switching duties in marine power distribution systems. As an Air Circuit Breaker, it provides reliable overcurrent and short-circuit protection across main switchboards, distribution panels, and generator circuits aboard commercial and industrial vessels. Its robust breaking capacity and wide voltage compatibility make it a critical component in maintaining uninterrupted power management and electrical safety at sea.
Key Features
✓ Rated current of 1250A with a matching 1250A sensor, suitable for high-load feeder and incomer protection in main and emergency switchboards.
✓ Insulation voltage of 1000V AC at 50/60Hz, with operational voltage ratings covering 380/440V and 480/690V, offering broad compatibility across marine electrical systems.
✓ Short-circuit breaking capacity (Icu) of 65kA and short-time withstand current (Icw) of 65kA for 0.5 seconds, providing robust fault tolerance under severe fault conditions.
✓ Undervoltage release rated at 230V AC, enabling automatic tripping upon loss of supply voltage — an important safety function in unattended machinery spaces.
✓ Designed for panel-mounted installation in main switchboards and motor control centres; replacement and servicing should be carried out by qualified marine electricians in accordance with onboard maintenance procedures.
Marine Applications
✓ Main switchboard incomer and bus-tie protection on merchant vessels, tankers, and offshore support vessels.
✓ Generator circuit breaker duties aboard bulk carriers, container ships, and RoPax ferries where high fault-level protection is required.
✓ Emergency switchboard and essential services distribution on vessels with strict power continuity requirements.
✓ Motor control centre (MCC) feeder protection for large auxiliary machinery including cargo pumps, HVAC compressors, and bow thrusters.
✓ Retrofit and replacement applications in existing Merlin Gerin or Schneider Electric switchgear installations across a wide range of vessel classes.
Why Marine Engineers Choose
The Masterpact M12 H1 is a well-established platform in marine electrical engineering, trusted for its high breaking capacity, wide voltage range, and reliable tripping performance in the demanding environment of shipboard power distribution. Its proven design makes it a preferred choice when maintaining switchgear integrity and minimising downtime during scheduled or emergency replacements.
Ideal For
Merchant vessels, offshore platforms, tankers, bulk carriers, container ships, RoPax ferries, dredgers, and any vessel class requiring high-capacity air circuit breaker protection in main or emergency switchboard configurations.
Technical Support
Technical support is available for the Merlin Gerin Masterpact M12 H1 Air Circuit Breaker, covering onboard installation guidance, fault diagnosis, and remote troubleshooting assistance. Support extends to integration within existing switchgear panels and general servicing queries.
