Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Multiple contact type
Patent
1999-10-15
2000-11-21
Donovan, Lincoln
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Multiple contact type
335 6, 335 15, 335129, 335172, 335177, 335178, 335194, H01H 6702, H01H 7500, H01H 900, H01H 300
Patent
active
061509094
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an electromagnetic switchgear unit having a pair of fixed contacts, a pair of fixed contact elements on which the fixed contacts are individually fastened, a movable contact element which is acted upon by a contact compression spring and has a pair of movable contacts on it which can be brought into and out of connection with the fixed contacts, a contact bridge carrier on which the movable contact element is held by means of the contact compression spring, a first electromagnetic drive appliance for rapid circuit breaking with a first armature and a coil, which is connected in series with one of the fixed contact elements, and a second electromagnetic drive appliance, with a second armature, for switching the load current on and off.
BACKGROUND INFORMATION
An electromagnetic switchgear unit is described in German Patent No. DE 43 18 196 A1. By means of this electromagnetic switchgear unit, load currents are connected and excessive currents, mainly short-circuit currents, are limited. In this case, the first electromagnetic drive appliance is operated as an auxiliary system which, in the case of excessive currents, exerts a force on the movable contact element and, by this means, opens the contacts. This therefore prevents the contacts being in an undefined floating condition, in which the contacts could become welded, due to electrodynamic forces. Such weld-free contactors are employed in association with a circuit-breaker. For economic reasons, the contactor is usually provided with a circuit-breaking capability which is lower than that of the circuit-breaker. Its current limitation only acts to support the circuit-breaker. It is therefore necessary for the auxiliary magnet system of the contactor to respond at a higher current than that of the circuit-breaker. It is also a requirement that the contacts should, in the case of a short-circuit, be held closed by the main magnet system until they are separated from one another by the auxiliary magnet system of the contactor. In order to satisfy these two requirements, magnet systems are necessary which are larger than those for standard units with the same switching capacity.
SUMMARY OF THE INVENTION
The present invention is based on the object creating an electromagnetic switchgear unit, of in which switch-off in the case of a short circuit takes place in association with improved measures for preventing welding of the contacts.
The object is achieved in accordance with the present invention in that the contact bridge carrier can be displaced in its longitudinal axis relative to the second armature, in that a compression spring engages with the contact bridge carrier, by means of which compression spring the motion of the second armature can be transmitted to the contact bridge carrier for contact opening, in that when the first electromagnetic drive appliance responds, the motion of the first armature is transferred to the contact bridge carrier in such a way that the contact compression spring is compressed in a first phase and, by this means, the contact pressure is increased and, at the same time, the compression spring also stores energy by means of which the contact bridge carrier is pressed, in a second phase, into the direction which causes the contact opening.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a sectional representation of a switchgear unit according to the present invention in the ON condition and carrying operational current.
FIG. 2 shows a sectional representation of the switchgear unit of FIG. 1 when a short-circuit current is applied.
FIG. 3 shows a sectional representation of the switchgear unit according to the present invention as shown in FIG. 1 after the auxiliary magnet system is triggered.
FIG. 4 shows a sectional representation of the switchgear unit according to the present invention of FIG. 1 in the OFF condition.
DETAILED DESCRIPTION
FIG. 1 shows an electromagnetic switchgear unit 1 with a contact system 2, a first electromagnetic drive appliance 3 an
REFERENCES:
patent: 4292611 (1981-09-01), Bresson et al.
patent: 4307358 (1981-12-01), Haury et al.
patent: 4491812 (1985-01-01), Happach
patent: 5163175 (1992-11-01), Mori et al.
Barrera Ray
Donovan Lincoln
Siemens Aktiengesellschaft
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