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

High reliability

1. Check-Out

In addition to the suitable materials and design, the construction itself and the careful assembly, we have reached our high quality also by the multiple checkouts of all parameters at every DPN. For that purpose, we have developed special testing stands including testing software.

To exclude the inaccuracies caused by the changed ambient conditions (temperature etc.), the gauging is done more times during a shift. A gauging sample is formed for every nominal current value and characteristic.

The checkout has following stages:

1. At the beginning, the parameters of the testing stand are corrected exactly according to the gauging sample
2. A triple check of the electromagnetic high-speed release with ejecting cage for short-circuit protection follows. There is evoked a situation when the short-circuits occur within a protected circuit.

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 or C). At this moment, 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 – now, the switch-off must occur with the standard requirements. This test procedure is repeated three-times.
 

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.

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3. INSTANTANEOUS RELEASE

It is a worldwide unique, recently patented principle of the instantaneous switching (our second Czech patent). This unique principle of instantaneous switching of contacts is based on the following facts: even when the lever is “stretched” very slowly, during the first stage the contacts inside the DPN only come near to each other to a distance that cannot create the condition for an electric arc. At this moment, the „coming-near“ is interrupted, even if the lever continues to be stretched.

With the next lever motion, it comes to the pre-stressing only inside the instantaneous mechanism. 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 DPN´s switch-on lever motion. The electric arc has almost no possibility to arise whereby the usual contact burning does not occur. We do not know any manufacturer who has solved this function at his DPN until now.

Another advantage of our solution is that the forces are transmitted always into the middle of the segments (we are the first manufacturer in the world) - therefore no crossing or misalignment of individual parts occurs. This design has a big influence on extension of both mechanical and electrical lifetimes (the number of switching cycles increases significantly)a as well as on the usually lightness of the lever running.

The above principle offers the following advantages:

1. The contacts can never be burnt, even with a very slow lever motion („stretching“); sometimes the terms „short-circuiting“ or so-called „burning-out“ of contacts are used. It is thus impossible to destroy the DPN in that way.
2. 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
3. Burning of contacts is reduced to a minimum level
4. The total DPN´s lifetime is extended essentially
5. DPN can be reliably used as a normal switch in according with the standard
6. The light lever running is surprising
    

4. HEAT REMOVAL

While developing the whole P-E-P series, thus also the DPN, we have taken into account the issues of thermal interactions of individual poles or modular devices.

At our DPNs of the P-E-P series, we have solved this problem by grooves on the sides of the casing. With vertical seating, the chimney effect of air streaming is enabled.

5. Casing Resistance to Gaping Upon Terminal Installation

It is a relatively usual problem on other DPN´s – upon an excessive screwing-up of the terminal, the casing opens or the terminal crosses in the casing. On some DPN´s, even the joints and thus the circuit are broken.

It is avoided on the DPN´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)

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6. Strong Design of Terminals

The movable terminal has been made of one piece. In contrast to other DPN´s, the joint has been solved by means of an overlapping and not by a so-called “puzzle joint”. Through this overlapping, there 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 torsional stress allowed by the standard is exceeded. (more than 2 N.m)

The clip terminals themselves have in their bottom part also the cross grooves which avoid the conductor to be taken out from the terminal (after being drawn up, the conductor sinks into the grooves). Simultaneously, the contact resistances are limited. (because of the enlargement of the transmission area the burning of the conductors is not possible).

The junction of a conductor and a DPN is very rigid and reliable.

7. Durability

The electromagnetic speed ejecting-cage release for protection against a short-circuit has been designed not to have any adjustable element. The characteristic curve of a DPN “B” or “C”) is given by the selection of the coil copper-wire’s diameter, the number of threads and the spring bias voltage in the coil core. This design excludes the possibility our DPNs to change the given characteristic curve by a falling-down or a shock in any way. top

8. 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 guarantees the reliability under different, even extreme operational conditions

9. Vibration Resistance

At other DPNs, 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 DPNs BONEGA®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 has simply been reduced significantly. The elements are interconnected by means of a modular design, or the parts are made of one piece.

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10. PRESS-PIECES MADE SOLELY OF TWO-SIDED MOULDS

The press-pieces of all plastic elements except for the levers have been solved solely with two-sided moulds. With this technology, we have reached the much higher dimensional accuracy, than with the three-sided moulds what guarantees a higher quality and following higher operational reliability.

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