New circuit breakers – M10H with rated currents of 80 and 100 A will soon appear in the ARMAT IEK line. These are the largest modular breakers in the ARMAT line – the width of one M10H pole is one and a half times that of ordinary circuit breakers. Compare: a familiar module is 18 mm wide, while an ARMAT M10H module is 27 mm.
But size isn't the only thing that matters in our new device. What else is notable about the ARMAT M10H? We'll tell you now.
Rated currents
As we already said, the M10H circuit breakers have two rated currents – 80 and 100 A. An immediate question may arise – why not just extend the ARMAT M10N line by adding new ratings?
By the way, both M10N and M10H comply with the "industrial" standard GOST IEC 60947-2.
It might seem that you could just change the settings of the thermal and electromagnetic releases, and the new rating is ready! But you can't cheat physics. At such rated currents, tripping in case of overcurrents (overload and short circuit) will lead to the release of a huge amount of heat. It is impossible to fit a design capable of handling such loads into a standard housing.
Modular breaker or power breaker?
Why create new modular products if IEK's range already includes molded case circuit breakers with similar parameters? The answer lies in the word "modular" – the M10H MCBs can be mounted on a DIN rail in one row with standard modular breakers. Apart from the module width, all other dimensions of the M10H are the same as those of conventional modular devices.
To install high-current M10H MCBs, you don't need large enclosures – just take a box for modular devices.
Modular circuit breaker or molded case circuit breaker? Each device has its own tasks.
If we're talking about molded case circuit breakers, it's worth mentioning another limitation that arises when using them. They are typically only available in three- or four-pole versions. Whereas modular circuit breakers M10H can consist of any number of poles from 1 to 4.
Torque and connection
The large housing dimensions of the M10H allowed the use of more powerful terminals and the connection of rigid conductive cores up to 50 mm2. Compare – for "compact" ARMAT circuit breakers, the maximum cross-section of a rigid core is 25 mm2. Cores can be clamped in the terminals with a rated torque of 5 N·m.
Arc quenching and contacts: double reliability
A fundamental difference from other modular IEK devices is the design of the arc chute, containing 24 plates. It consists of two parts – one for each pair of contacts.
For effective arc drawing from the switching contacts and faster arc quenching, a copper-plated ferromagnetic strap is installed. And to vent hot gases at the moment of short-circuit current interruption, the arc chute is separated by a protective shroud made of absorbent material. The shroud has channels for gas venting.
You've probably already wondered: why is the arc chute double? After all, we're talking about one pole? The fact is that breaking in the M10H occurs via two switching contacts. Just like in load switches and contactors, the M10H uses a bridge contact. The contact system with double break provides more reliable opening with less contact wear.
This system is used in IEK circuit breakers for the first time.
But we went even further – for effective short-circuit current interruption, the switching contacts are placed in a ferromagnetic arc-quenching cocoon with overlays made of insulating material.
Of course, the contact tips on the moving and fixed contacts are made of refractory material with low transition resistance – carbon silver AgC5, as in all modular IEK devices from the KARAT and ARMAT lines.
Thanks to the improvements, we managed to achieve the following parameters for the high rated currents of 80 and 100 A:
· Rated ultimate breaking capacity Icn – 10 kA.
· Mechanical endurance – 20,000 cycles.
· Electrical endurance – 5,000 cycles.
A few more facts about the new device
· The M10H design allows connecting up to 4 additional devices from the ARMAT line on the left.
· The quick-acting trip-free mechanism opens the contacts regardless of whether the manual operation handle is held or not. And instant switching reduces the time of transient processes during contact closing and opening.
· Like in all modular ARMAT devices, the M10H has an indicator (mechanical flag) of contact position. Red color means the ON state, green – OFF.
· The M10H MCBs are produced with a wide range of electromagnetic release characteristic types: known B, C, D, as well as specific Z, L, K.
Where can M10H breakers for 80 and 100 A be used?
The main area of application is main distribution boards, distribution boards, and floor boards. For example, an M10H MCB with a D100 rating can be installed at the input to a household with a large allocated power. And a B80 breaker can be a group breaker, powering an electric sauna.