Circuit Protection Devices » BONEGA® P-E-P Miniature Circuit Breakers

1. Quality Control

The high quality of our product is due to a combination of materials, design and thorough testing of each miniature circuit breaker.

1. a triple check of the electromagnetic high-speed release with ejecting armature for short-circuit protection
   
   Every piece manufactured passes through a testing stand controlled by the computer. At that stand, there is verified the function of the circuit breaker on the undermost limit of the required nominal current value for given characteristics (B, C or D) by which the switch-off must not occur yet; after that, the current test of the upper limit of the nominal current value of the given characteristic follows immediately - under this current the velocity of circuit-breaker switching-off must not exceed 0,1 s. This test procedure is repeated three-times.
    
2. a double check of the time-limit thermal release for overload protection (if the circuit has not been damaged but a significant overload occurred which could damage the electrical installation)
   
   The thermal release test is done two-times at least until the bi-metal is not mechanically adjusted to the required value. Between particular tests, the circuit breaker is left to cool down!
   
   The complete test pursuant to CSN EN 60898 - a long-term test of the thermal release at random chosen samples - is performed at least once a shift.
    
3. at least a fivefold mechanical reliability check: This test is a part of the two aforementioned tests during which the switching-on and switching-off mechanisms are verified.

2. Pride of Workmanship

Every circuit breaker is stamped describing the characteristics, nominal current value, month of manufacture (since the beginning of the production) and the number of the individual worker who has assembled the product. In this way the workers are motivated to bear the liability of their labor.

3. Instantaneous Switching of Contacts

A worldwide unique, recently patented principle of the instantaneous switching where the forces are transmitted only into the middle of segments – therefore no crossing occurs (no world manufacturer has developed that solution yet). This solution has a big influence on extension of both mechanical and electrical lifetimes in connection with the number of switching cycles.

This unique principle of instantaneous switching of contacts is based on the following facts: even when the MCB lever is stretched very slowly, during the first stage the contacts inside the MCB only come near to each other to a distance which cannot create the condition for electric arc. In this moment the „coming-near“ is interrupted, even if the lever continues to be stretched (switched-on). In this moment the second stage begins – i.e. pre-stressing only inside the instantaneous mechanism when the contacts does no come near to each other more, but the lever is moved. Upon the pre-stressing, stated in advance, the third stage begins – i.e. a heavy high-speed switching of internal contacts. This switching is, however, fully independent on the rate of contact lever motion.

The above principle offers the following advantages:

• the contacts can never be burnt even not with a very slow MCB lever motion („stretching“); sometimes the terms „short-circuiting“ or so-called „burning-out“ of contacts are used. It is thus impossible to destroy the MCB in that way.
• by a heavy high-speed switching of contacts, a perfect touch is secured even at very low values of nominal current – such touch excludes any wrong power transfer
• burning of contacts is reduced to a minimum level
• the total MCB's lifetime is extended

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4. Casing Resistance to Gaping Upon Terminal Installation

It is a usual problem on other MCB´s – upon tightening of the terminal, the casing opens or the terminal cross threads in the casing. On some MCB´s, even the joints and thus the circuit are broken.

It is avoided on the MCB´s BONEGA® P-E-P by means of:

• plastic guides for the movable parts of the terminal, which has been chosen properly
• press-pieces in the casing body
• places for rivets, chosen properly
• plastic pins (the casing has no butt joins)

5. Extremely Rigid Design of Terminals

The movable terminal has been made of one piece. In contrast to most other MCB´s, the joint has been solved by means of an overlapping and not by a so-called “puzzle joint”. Through this overlapping goes a screw. It has a double thread length available, which restricts the breaks – “stripping” the thread essentially. The possibility to break it when being mounted is fully excluded even if the torque allowed by the standard is exceeded (more than 2 N.m).

In the bottom part of the clip terminals is the cross grooves which avoid the conductor to be taken out from the terminal (after tightening, the conductor sinks into the grooves). Simultaneously, the contact resistances are limited. (because of the enlargement of the transmission area the burning of the conductor is not possible).

The junction of a conductor and BONEGA^® P-E-P MCB is very rigid and reliable.
 

6. Durability

The design of the electromagnetic high-speed release with ejecting armature for short-circuit protection has been solved so that it has not any adjustable element. Its characteristic is given by the cross-section of the copper wire of the coil, by number of threads and spring pre-stressing in the core. This solution thus excludes that our circuit breakers could change their presented value by a fall or shock. to the top

7. Thermal Dilatation Resistance

The mechanism's function is not affected by thermal dilatation. The design allows possible plays (by dilatation, shock, wearing) to be accepted without any affect on the function of movable parts, such as switching mechanism, movable contact, ejecting coil, indication etc. This unique solution improves the quality essentially but especially it warranties the reliability under different, even very extreme operational conditions.

8. Vibration Resistance

Strong vibrations can cause the short-circuit release to be put out of service (it loses its protective function) or the spot-welds to be disconnected (current interruption).

 

a) measures avoiding the short-circuit release to be put out of service

The MCB´s BONEGA® P-E-P are protected against the above phenomenon by a suitable seating of the structure elements, especially of the ejecting coil which is seated in a unique “cradle” (see the Fig.). This design has excluded the possibility to misalign and consequently to seize the movable core at the coil.

b) measure avoiding the spot welds to be disconnected

The quantity of spot-welds can be reduced significantly. The elements are interconnected by means of a modular design, or the parts are made of one piece.

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9. Extraordinary MCB's Body Strength

The casing design ensures strength not only of a single-module type, but even in case of multi-module circuit breakers.   Strength: a sophisticated placing and number of rivets amount of pivot joints design of the casing with stabilizing locks and pivot joints. to the top

10. Two Side Molds

The press pieces of all parts, except for the lever, are made from two-side molds. Because of this technology, we have reached much higher dimensional accuracy, thus higher quality, resulting in higher operational reliability.

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