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[ EN ]


Improvements in Electromagnetic devices

Field of Invention

This invention relates to electromagnetic devices which employ solenoids, such as electrical contactors and more especially to a contactor for use in controlling a domestic supply of electric current.

Background to the Invention

The solenoid employed in a contactor of known type has a frame carrying a solenoid winding surrounding a plunger protruding from one end of the frame to carry the moving contact (s). The contactor also has a permanent magnet for holding the contactor closed. This magnet is usually housed within the confines of the frame at the end from which the plunger protrudes. Space for the magnet is created by terminating the winding short of this end of the frame. Thus, for a given size of solenoid frame or profile, the space available for the coil is
disadvantageously reduced. Moreover, the "stopping short" of the coil can lead to wastage of useful magnetic flux, especially when the solenoid is energised.

The Invention

According to the present invention, in an electromagnetic device such as a solenoid which has a frame accommodating a winding surrounding an operating plunger permanent magnet means for latching the solenoid is disposed
laterally outside the winding at the end thereof from which the plunger protrudes from the frame. This enables the full length of the frame to be used for the winding and minimises flux wastage.

A latching solenoid embodying the invention may be
employed advantageously in a contactor, wherein the moving contac (s) are carried by or operated by the plunger.

It is a feature of a contactor constructed in accordance with the invention that the energy required to close the gap and "make" the contact is relatively small. Such a contactor is especially suitable for remote control, as by a radio signal, and a further feature therefore provides the combination of the afore-mentioned contactor with a signal receiving device through which the contactor is activated.

A still further feature concerns the combination of the contactor with an electric current meter for a domestic supply.

The invention thus provides a contactor which can be used, for example, to enable domestic electricity supplies for heating water and for storage radiators to be controlled by a radio signal from a remote source, e.g. a standard broadcast radio signal having added coding.

For control of storage radiators relatively high amperage contacts are necessary, whilst lower amperage contacts are sufficient for the control of hot water heaters.

The invention also provides a housing capable of receiving either one or both of two contactors , one having high current contacts and the other lower current contact .

When a second contactor is inserted into the housing , a common power-in terminal is advantageously establi shed wi th the host contactor already present in the housing .

A manual override may protrude from the housing , which housing may itself be embodi ed in, or constitute the hous ing of , a domestic current meter .

For reasons of power economy, when a contactor is remotely controlled by radio in the afore-mentioned manner , the signal duration is preferably not more than 50 ms . The contactor must therefore remain in the set and reset
( on/of f ) conditions for long periods , without power consumption. The contactor in accordance with the invention is especially suited to this purpose .

The invention will now be described with reference to the accompanying drawings which illustrate the invention as applied to latching solenoids for use in remotely
controllable contactors .

Description of Drawings

In the accompanying drawings : -

Figure 1 i s a view of a hous ing , front panel removed , containing 100A and 25A contactors ;

Figure 2 is an end view of the device;

Figures 3 and 4 show the 100A contactor, respectively when set (closed) and at rest (open);

Figure 5 is a perspective view of the 25A contactor; and

Figure 6 is a perspective view of the closed housing accommodating the two contactors .

Description of Embodiment

Referring to the drawings, a housing 10, e.g. to be accommodated in a domestic current meter, accommodates a 100A contactor 12 for storage radiator control and a 25A contactor 14 for water heater control. A terminal board 16 enables the delivery of on/off signals by which the contactors can be remotely switched on and off, as by radio.

As also exemplified by Figures 3 and 4, each contactor has a double wound latching solenoid 18 with permanent magnet members 20 at one end of a frame 22.

The fixed terminals for power in and power out of the 100A contactor are designated 24, 26. The lead-off from the power out terminal 26 is of a box-shape configuration 28. A moving blade assembly comprises moving blade 30, blade carrier or plunger 32, and return spring 34. Reference 36 denotes a solenoid stop by which an air gap 38 is
maintained in the rest condition of the contactor.

When the solenoid double winding is energised, the
contacts 24, 26 are closed by blade 30 and even though the controlling signal is transitory, the substantial closing of the air gap 38 enables the permanent magnet 20 to hold the contactor in the set condi tion until a revers ing f ield i s produced by another controlling radio signal . Figures 3 and 4 show the 100A contactor when set and at rest, whilst Figure 5 ( see also Figure 2 ) shows the 25A
contactor, which is generally of similar construction for remote control, except that the fixed and moving contacts close via a cranked arm 40. Reference 42 denotes the power-out terminal of the 25A contactor .

Figure 6 shows the housing 10 when closed by a front panel . A manual override lever 44 ( see also Figure 1 ) protrudes from the housing , as well as the power-in and power-out terminals . It is to be noted that, assuming the housing to contain only the 100A contactor, if the 25A contactor is then inserted , the power-in terminal 46 of the 25A contactor is automatically brought into
engagement with the power-in terminal 24 of the 100A contactor, and can be brazed or spot welded or otherwi se secured to the terminal 24.

Where for example the frame is replaced by a so-called C-frame, in a solenoid , a single magnet may be employed in place of the two shown in Figures 3 and 4.

Various modi fications of the above -de scribed embodiment are possible within the scope of the invention
hereinbefore def ined .