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ADJUSTABLE TRIPPER BAR
FOR ELECTRIC LINE PROTECTION APPARATUS
The present invention relates to the technical area of electric apparatus and
more particularly to the area of modular electric devices of circuit breaker or switch
type used to protect lines with a view to ensuring the safety of persons.
More precisely the invention concerns the actuation of a locking mechanism
such as those which equip thermal magnetic circuit breakers or devices of this type,
phase circuit breakers for example.
Conventionally, circuit breakers for line protection comprise, in an insulated
case, a circuit that extends between two terminals and contains a thermal trip
bimetal to protect against electric overloads and an electromagnetic actuator
essentially having a coil cooperating with a mobile magnetic core associated with a
striker so that in the event of a surge the circuit is broken through the opening of a
moving contact cooperating with one or more fixed contacts. Phase and neutral
circuit breakers, in addition to the phase stage just described, comprise a neutral
stage also with fixed and moving contacts, the moving neutral contact being
actuated conjointly with the moving phase contact.
The movement of the moving contact towards or away from the fixed contact
is conventionally piloted by a latch-type locking mechanism manually actuated by a
command handle driving a rod which tends to push back a pivoting contact holder to
bring each moving contact into contact with a fixed contact, a position in which the
reverse movement is normally opposed by a pawl preventing the rod, with latch-type
bearing on the contact holder, to escape and release itself.
Manual opening is made by activating the handle in the reverse direction.
Circuit breaking is caused by action of the bimetal or striker of the magnetic actuator
against a trip to cause release of the pawl and hence release of the rod resulting in
the opening of the electric contact. Said locking mechanism is described for
example in European patent 0 570 647 B1.
The thermal subassembly comprising the bimetal is therefore intended to trip
the locking mechanism so as to release or open the electric contacts and interrupt
circulation of the current in the modular apparatus. Tripping the lock must be made
when the intensity circulating in the electric circuit exceeds a predetermined
threshold. The bimetal must therefore be accurately positioned so that its deflection
is sufficient, once this threshold is reached, to ensure tripping. The operating
reliability and accuracy of the modular electric apparatus are dependent thereupon.
This apparatus must therefore be equipped with adjustment means with

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which to ensure that the bimetal positioning is compatible with the desired trip
threshold. This positioning and trip management must also take into account the
existence of a tripper bar between the bimetal and the locking mechanism.
Adjustment of positioning is conventionally made by deformation of an elastic
part, in metal for example, supporting the bimetal. One condition for adjustment
efficacy is the stability of the trip threshold, hence the stability of the positioning of
the bimetal; it is therefore essential that the deformation of the elastic part should be
fully reversible, which implies that during operation the elastic limit of the constituent
material of the bimetal support part should not be exceeded.
It is known for example to use a stainless steel spring associated with this
support part whose adjustment can be made via a screw whose head is accessible
from outside the casing.
The purpose of the present invention is to achieve a protective thermal
subassembly for modular electric apparatus ensuring an accurate and reliable
predetermined trip threshold whilst overcoming the risk of faulty reversibility
attributable in particular to the elastic supports when adjusting the trip threshold.
A further purpose of the present invention is to simplify the constituent
elements of this thermal subassembly and the assembly operations of said
subassembly in the modular electric apparatus.
Since the conventional solution using an elastic support requires several
components, it is also of advantage in this invention to obtain a reduction in the
number of constituent parts of the protective thermal subassembly and therefore to
achieve a significant reduction in manufacturing costs.
According to the invention, as main characteristic the adjustment means are
integrated in the tripper bar.
This overcomes the frame restrictions represented by the casing in plastic
material, whose dimensional variations related in particular to hygrometric changes
may affect adjustment of the bimetal. The plastics chosen for casings are sensitive
to ambient humidity and undergo deformations which may influence the cold
position of the bimetal and hence its action. It is true that plastics can be found
which are insensitive to hygrometric variations but these are more costly and the
financial consequences for a casing are dissuasive.
With the solution of the invention it is possible to use this type of plastic
solely for the tripper bar, a part whose size is such that the economic impact is
negligible.
Finally the invention does away with the elastic support part used to adjust
bimetal positioning.

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Preferably the tripper bar slides in translation within the casing and has two
active contact zones facing the opposite direction to the direction of sliding, said
active zones being respectively designed to be driven by the bimetal and to act on
the locking mechanism, the adjustment means allowing modification of the distance
between them.
Up until now tripper bars have never served as adjusting elements and are
therefore parts whose shape is not subject to modification.
The originality of the invention lies in the possibility of modifying the
dimensions of the tripper bar and hence of adapting it to the positioning of the
bimetal rather than the reverse.
Further preferably the adjustment means act on the positioning of at least
one of the active zones with respect to the other.
For economic reasons however only one of the active zones will be
adjustable in most considered possibilities.
According to one possibility, the tripper bar is U-shaped and its bottom part
slides in the casing, its branches comprising the active zones.
This shape, conventional as such, lends itself naturally to the invention; the
bottom of the U provides a guiding/slide element beneficial to sliding whilst the
branches have opposite facing zones onto which it is easy to associate adjustment
means intended to modify the distance separating them.
According to a preferred configuration, the active zone cooperating with the
bimetal consists of the free end of an element projecting beyond a branch in the
direction of the bimetal and adjustable parallel to the bottom of the tripper bar.
Adjustment is therefore made parallel to movement which complies with the
optimising of each adjustment operation.
More precisely, said adjustable element is a self-tapping screw fixed to the
branch.
The adjusting operation is simple as is the securing of the adjustable element
to a branch; in terms of industrialisation this solution is favourable and low cost.
According to one possibility the element projecting beyond a branch faces
towards the inside of the U, the other active zone cooperating with the locking
mechanism therefore also facing towards the inside of the U.
In this configuration, one of two possibilities, the tripper bar partly surrounds
the locking mechanism and the active zones face one another.
In the possibility under which the apparatus of the invention comprises an
electromagnetic subassembly ensuring the parting of the fixed and moving electric
contacts in the event of a short-circuit, the bimetal may for example have one end

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welded to one end of the coil of said electromagnetic subassembly which is fixed
with respect to the casing.
In this way it is possible to use only one electric connection braid fixed to the
bimetal, thereby further reducing the number of constituent parts of the electric
apparatus.
Other characteristics and advantages will become apparent from the
following detailed description with reference to the appended drawings in which:
figure 1 shows part of a protective thermal subassembly according to the
invention,
figures 2 and 3 show details of figure 1.
figures 4 and 5 show the bimetal of the electric apparatus according to the
invention in two different operating positions.
The present invention concerns a modular electric apparatus, for example
comprising a casing in plastic material (not shown) with which a support structure 1
cooperates, partly shown figures 4 and 5. More precisely, the electric apparatus
comprises at least two electric connection terminals and a command handle 2 which
can be moved between two stable positions and driving a locking mechanism 5
piloting the opening and closing of the electric connection between the two
connection terminals.
A fixed electric contact and a moving electric contact open and close the
electric connection respectively under the action of the locking mechanism 3. The
moving electric contact 4 is driven directly by the locking mechanism. The fixed
electric contact consists for example of a contact pad 5 integral with an induction coil
6 (see figure 1).
The electric apparatus also comprises a thermal trip bimetal 7 acting on the
locking mechanism 3 via a tripper bar 8.
The tripper bar 8 is shown in more detail figures 1, 2 and 3 and moves inside
the casings to act on the locking mechanism 3. It has one end 8a conformed to act
on the locking mechanism 3 so as to release the moving electric contact 4 from the
fixed electric contact 5. The means for adjusting the trip threshold, according to the
invention, are integrated in the tripper bar 8.
These adjustment means can be used to adjust the distance between an
abutment 8a arranged at one end of the tripper bar 8 and having an active surface
8c, and a mobile element 11 whose active surface 10 intended to come into contact
with the free end 7a of bimetal 7 is oriented in the opposite direction to surface 8c.
Mobile element 11 which in fact forms the adjustment means is arranged in
an abutment 8b of the tripper bar and is here in the form of a self-tapping screw 11

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whose free end is the active surface 10.
Abutment 8a acts via its surface 8c on the locking mechanism 3, whilst
abutment 8b adjustable according to the position of screw 11 interacts with bimetal
7. Screw 11 is screwed into the bottom of a bore 12 for example made in the
constituent material of the tripper bar 8. The distance between the active surfaces
(8c, 10) is adjusted so that it adapts to the distance between the bimetal 7 and the
locking mechanism 3, or more particularly the wall of said mechanism 3 against
which the active surface 8c acts.
The electric apparatus, when it comprises an electro-magnetic subassembly
to ensure parting of the fixed and moving electric contacts if a sudden surge occurs,
is equipped with an induction coil 6 of which an example is shown figure 1. The
other end 7b of bimetal 7 can then be fixed for example to one end 14 of said coil 6.
The electric current therefore passes through induction coil 6 and bimetal 7 on which
an electric connection braid, not shown, is also connected. The fixing of the bimetal
7 onto end 14 of the induction coil 6 is made by any known means, in particular by
weld points.
Figures 4 and 5 show the bimetal 7 in two positions corresponding to a rest
position and an active position respectively. The latter position releases the moving
electric contact 4 from the fixed electric contact 5 in response to reversible
deformation of the bimetal 7. The free end 7a then comes to bear against the mobile
abutment 10 to drive the tripper bar 8 in translation which in turn acts on the locking
mechanism 3.
The inventive modular electric apparatus forms a circuit breaker for example.
In another embodiment the modular electric apparatus may be an electric switch.

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WE CLAIM
1. Modular electric apparatus for the protection of an electric line comprising,
in a plastic material casing:
- at least two connection terminals to the electric line,
- a command handle (2) able to move between two stable positions, driving:
- a locking mechanism (3) piloting the opening and closing of the electric connection
between the two connection terminals,
- a fixed electric contact and a moving electric contact, opening and closing the electric
connection under the action of the locking mechanism (3),
- a thermal trip bimetal (7) acting on the locking mechanism (3) via a tripper bar (8) in the
event of an electric overload on the line, said tripper bar having a float arrangement in
the casing,
- and means for adjusting the trip threshold of the bimetal (7);
characterized in that the adjustment means are integrated in the tripper bar (8).
2. Electric apparatus as in claim 1, characterized in that the tripper bar (8)
slides in translation within the casing and has two active contact zones (8c, 10) oriented in
the opposite direction with respect to the direction of sliding, said active zones (8c, 10)
being respectively designed to be driven by the bimetal (7) and to act on the locking
mechanism (3), the adjustment means (11) being used to modify the distance between
them.
3. Electric apparatus as in the preceding claim, characterized in that the
adjustment means (11) act on the positioning of at least one of the active zones (8c,10)
with respect to the other.
4. Electric apparatus as in either of claims 2 and 3, characterized in that the
tripper bar (8) is U-shaped whose bottom part slides in the casing and the branches
comprise active zones (8c, 10).
5. Electric apparatus as in the preceding claim characterized in that the active
zone (10) cooperating with the bimetal(7) consists of the free end of an element (11)
projecting beyond a branch in the direction of the bimetal (7) and adjustable parallel to the
bottom of the tripper bar (8).

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6. Electric apparatus as in the preceding claim, characterized in that said
adjustable element is a self-tapping screw (11) fixed to the branch.
7. Electric apparatus as in either of claims 5 and 6 characterized in that said
element (11) projects beyond the branch towards the inside of the U, the other active zone
(8c) cooperating with the locking mechanism (3) then also facing towards the inside of the
U.
8. Electric apparatus as in any of claims 1 to 7, characterized in that it
comprises an electromagnetic subassembly ensuring the parting of the fixed (5) and
moving (4) electric contacts in the event of a short circuit.
9. Electric apparatus as in claim 8 characterized in that the bimetal (7) is fixed
to one end (14) of an induction coil (6) of the electromagnetic subassembly, which is fixed
with respect to the casing.
10. Modular electric apparatus as in claim 8 or 9 characterized in that it forms
an electric circuit breaker.
Dated this 28th day of September, 2005

Modular electric apparatus for the protection of an electric line comprising, in the plastic
material casing.
- at least two connection terminals to the electric line,
- a command handle (2) able to move between two stable positions, driving:
- a locking mechanism (3) piloting the opening and closing of the electric connection
between the two connection terminals,
- a fixed electric contact and a moving electric contact, opening and closing the electric
connection under the action of the locking mechanism (3),
- a thermal trip bimetal (7) acting on the locking mechanism (3) via a tripper bar (8) in the
event of an electric overload on the line, said tripper bar having a float arrangement in
the casing,
- and means for adjusting the trip threshold of the bimetal(7), which are integrated in the
tripper bar (8).