EP0898781B1 - Process for adjusting a thermal overload cut-out - Google Patents

Description

The invention relates to adjustment methods for thermal Overload release with bimetal strips, with a tap system and with a trigger mechanism that a Has adjusting device, the position of the first Bimetallic strip is adapted to the tap system and one Pre-adjustment of the trigger mechanism by setting a predetermined trigger distance is made before the A certain current can be applied to the bimetal strip.

A generic adjustment method for a thermal Overload release with bimetal strips, with a tap system and with a trigger mechanism, the adjustment device has already been known from FR-A-266 79 79. The position of the bimetallic strips is shown first adapted the tap system and a pre-adjustment of the trigger mechanism by setting a predetermined trigger distance made before the bimetallic strips with a certain current can be applied.

It is also known that protective devices with time delays Overcurrent releases according to regulations within certain response limits must trigger (e.g. IEC 947-2, IEC 947-4-1). According to these regulations, the load must be 1.2 times Trigger current within 2 h and when loaded with 1.05 times the set current tripping must not take place within 2 hours of current load. For devices with thermal overload releases this mostly through the implementation of the electricity via the heat of electricity in bending bimetallic strips and adjusting one mechanical system that includes a step function reached to these bimetal strips.

The effective deflection of the bimetal strips depends on several Influencing factors, e.g. the current path resistance of the thermal overload release, the specific deflection the bimetallic strip, the release force and suspension of the mechanical Systems etc. It results for everyone Protection device individual bends.

2 shows a schematic diagram of a known thermal Overload release. This contains three bimetal strips 1, a mechanical tap system 2 and a trigger mechanism 3 with a compensation strip and with an adjustment device 5. In the known adjustment method is from a medium effective deflection with identical protective devices went out. This deflection path is called the distance y between the bimetal strip and the mechanical switch-off point of the trigger mechanism set (pre-adjustment) after the position of the bimetal strips adapted to the tapping system was (synchronization). Then the trigger time the thermal overload release at a certain current measured. If the trigger time is outside of a specified one Time window determined by the current response limits the distance must be corrected depending on the time deviation. After the protective device has cooled to ambient temperature the tripping time measurement is repeated.

In order to ensure the response limits according to regulations, Sampling measurements of the response limits carried out. If the results show a tendency to change the response limits, these become by shifting the time window when checking the tripping time to the middle of the response limits corrected according to regulations.

The invention has for its object the above Adjustment procedure to improve in such a way that taking into account the individual bend the prescribed Response limits can be met without having to repeat tests and thus the time-consuming cooling down to to the ambient temperature are necessary.

The first object is achieved in that the release distance is such that after deflection the bimetal strip due to the current load for one predetermined duration of the trigger mechanism at the end of this Duration not yet triggers, but a residual trigger distance Δy is present at the end of the duration by a device to zero, i.e. reduced until the trigger mechanism is triggered becomes.

Advantageous further developments of the adjustment method are the Subclaims 2, 3 and 4 can be found.

FIG 1

einen Ablaufplan eines Justierverfahrens für einen thermischen Überlastauslöser,

FIG 2

eine Prinzipskizze eines bekannten Überlastauslösers und

FIG 3

eine Vorrichtung mit Antrieb zur Justierung.

Embodiments of the invention are explained below with reference to a drawing. Show it:

FIG. 1

a flow chart of an adjustment procedure for a thermal overload release,

FIG 2

a schematic diagram of a known overload release and

FIG 3

a device with drive for adjustment.

The invention is based on a known overload release explained according to FIG 2, already at the assessment of the prior art described in the introduction to the description has been.

In the adjustment method according to the invention, its flow chart 1 is shown, the individual bimetal strips 1 with small tolerances on the mechanical Tap system 2 adapted (synchronization). In the subsequent Pre-adjustment becomes a defined initial state with a certain trigger distance to the actual one Adjustment process made. Adjusting the thermal Overload release is usually done when this is already installed in the protective device. The following now Current load of the bimetallic strip 1 takes place in which all Poles of the protective device can be connected in series. In doing so the bimetallic strips 1 for a predetermined duration T. a current that is a multiple of the setting or rated current. At the end of the current load period T exists between the mechanical system 2 with two the bimetal strip 1 and the trigger mechanism 3 a residual trigger distance Δy by a device 7 with a drive 3 to zero and thus reduced until tripping becomes. As a result, the entire mechanical system 2 and the bimetal strips 1 included in the adjustment process. The individual tolerances of the protective devices are thus considered. The individual bending of the bimetallic strips 1 is due to the bending of the bimetallic strip 1 in the direction of the pillar during the current load period T simulated.

The device 7 according to FIG. 3 has to reduce the Residual trigger distance Δy a drive, e.g. a stepper motor or a linear motor which is connected via coupling means 8 the adjusting device 5 of the trigger mechanism 3 with this can be mechanically linked. The drive is expected values with regard to its speed of the residual trigger distance Δy adjusted such that on the one hand whose reduction to zero can be reached quickly, whereby a rapid braking to zero speed at the moment must be ensured by triggering or the angle of rotation error can be corrected. This means, that the drive when the mechanical switch-off point is reached 6 remains as undelayed or defined as possible. The drive can be used, for example, via a gear wheel 8 as a coupling means be coupled to the adjustment device 5.

In order to ensure the response limits according to regulations, In turn, random measurements of the response limits were carried out. The results show a trend change of the response limits, these are changed by regulation the current load duration during the adjustment process Corrected middle of response limits.

The adjustment procedure is for all devices with thermal Overload releases that apply the current in a proportional Form the path and convert it to a mechanical system let it work.

Claims (4)

1. Process for adjusting a thermal overload release having bimetal strips (1), having a pick-off system (2), and having a release mechanism (3) which has an adjusting device (5), wherein first of all the position of the bimetal strips (1) is matched to the pick-off system (2) and a preadjustment of the release mechanism (3) is carried out by setting a predetermined release distance (y), before a certain current is applied to the bimetal strips (1), characterised in that the release distance (y) is dimensioned in such a way that after the bimetal strips (1) have bent outwards because of the current load for a certain duration (T), the release mechanism still does not release at the end of this duration (T), but instead there is a residual release distance (Δy) which, at the end of the duration (T), is reduced to zero, i.e. until the release of the release mechanism, by a device (7) by way of the adjusting device (5).
2. Adjusting process according to claim 1, characterised in that the device (7) has a drive.
3. Adjusting process according to claim 1 or 2, characterised in that the device (7) effects a travel sufficient to reduce the residual release distance (Δy) to zero, so that the release takes place.
4. Adjusting process according to one of the preceding claims, characterised in that the drive is matched in terms of speed and inertia to the residual release distance (Δy) in such a way that, on the one hand, the reduction of the residual release distance (Δy) to zero takes place quickly and, on the other hand, the drive is braked as quickly as possible when the release is achieved.

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