CN213025861U

CN213025861U - Power switch

Info

Publication number: CN213025861U
Application number: CN202021196680.6U
Authority: CN
Inventors: 王宁; 刘振忠; 余刚; 李莎
Original assignee: Schneider Electric China Co Ltd
Current assignee: Schneider Electric China Co Ltd
Priority date: 2020-06-24
Filing date: 2020-06-24
Publication date: 2021-04-20
Anticipated expiration: 2030-06-24

Abstract

There is provided a power switch, comprising: a first stationary contact configured to be connected to a first power source; a first movable contact configured to rotate about a first pivot axis, a first contact end of the first movable contact being in electrical contact with the first stationary contact in a first closed position, and the first movable contact being separated from the first stationary contact in a first open position; and a conductor configured to connect the first load end of the first movable contact to a load and including at least one first sub-section disposed proximate to and extending generally along a first portion of the first movable contact between the first load end and the first pivot axis. When the first movable contact is in the first closed position, the first contact end of the first movable contact is biased toward the first stationary contact by electromotive force caused by the current in the first sub-section and the current in the first portion. The contact between the first moving contact and the first fixed contact is reliably maintained, and the short-time current endurance capacity of the power switch is improved.

Description

Power switch

Technical Field

The present invention relates to a power switch, and more particularly to a power switch with contact pressure compensation.

Background

Some power switches, such as load switches and automatic transfer switches in low-voltage electrical switches, require a certain short-time current withstand capability. The higher short-time current withstand capability indicates that the power switch can be kept closed when a short-circuit current or an overcurrent flows until a protection device such as a circuit breaker trips to break the short-circuit current or the overcurrent. The power switch may comprise, for example, a dual power transfer switch.

SUMMERY OF THE UTILITY MODEL

At least one embodiment of the present disclosure provides a power switch, including: a first stationary contact configured to be connected to a first power source; a first movable contact configured to rotate about a first pivot axis and movable between a first closed position in which a first contact end of the first movable contact is in electrical contact with the first stationary contact and a first open position in which the first movable contact is separated from the first stationary contact; and a conductor configured to connect a first load end of the first movable contact opposite the first contact end to a load and including at least one first sub-section disposed proximate to and extending generally along a first portion of the first movable contact between the first load end and the first pivot axis. When the first movable contact is in the first closed position, the first contact end of the first movable contact is biased toward the first stationary contact by electromotive force caused by the current in the first sub-section and the current in the first portion.

Therefore, the contact between the first movable contact and the first fixed contact is reliably maintained, and the short-time current endurance capability of the power switch is improved.

For example, in some embodiments, the at least one first sub-section is two or more first sub-sections. The conductor includes a helically extending first conductor portion including two or more turns, each of the two or more turns including one of the first sub-segments.

Thus, a greater electrodynamic force can be generated, the ability of the power switch to maintain contact between the first movable contact and the first stationary contact being enhanced.

For example, in some embodiments, the at least one first sub-section is two first sub-sections. The conductor includes a helically extending first conductor portion including two turns, each of the two turns including one of the first sub-segments. A first portion of the first movable contact is arranged between the two first subsections in a direction perpendicular to the plane of the two turns.

Therefore, more stable and more balanced electromotive force can be provided, and the layout of the power switch can be made compact.

For example, in some embodiments, the first movable contact is at a distance in the range of-1-3 mm from the first portion when the first movable contact is in the first closed position.

For example, in some embodiments, the first movable contact is at a distance in the range of 0.1-2mm from the first portion when the first movable contact is in the first closed position.

For example, in some embodiments, the first movable contact is at a distance in the range of-1-0 mm from the first portion when the first movable contact is in the first closed position.

For example, in some embodiments, the power switch is a dual power transfer switch, further comprising: a second stationary contact configured to be connected to a second power supply; and a second movable contact configured to rotate about a second pivot axis and movable between a second closed position in which a second contact end of the second movable contact is in electrical contact with the second stationary contact and a second open position in which the second movable contact is separated from the second stationary contact. When the second movable contact is in the second closed position, the second contact end of the second movable contact is biased toward the second stationary contact by an electrodynamic force caused by the current in the second sub-section and the current in the second section. And, the conductor is further configured to connect a second load end of the second movable contact opposite the second contact end to the load, and further comprising: at least one second sub-section disposed proximate to and extending generally along a second portion of the second movable contact between the second load end and the second pivot axis; and at least one common section connecting the at least one first sub-section and the at least one second sub-section, and one of the at least one common section is configured to be connected to the external load.

Therefore, the contact between the first moving contact and the first fixed contact and the contact between the second moving contact and the second fixed contact are reliably maintained, and the short-time current tolerance of the power switch is improved.

For example, in some embodiments, the conductor further includes a third sub-section and a fourth sub-section. The at least one common section includes a first common section and a second common section configured to be connected to the external load. The first load end of the first movable contact is connected to the load via the third sub-section, the first common section, the first sub-section, and the second common section in this order. The second load end of the second movable contact is connected to the load via the fourth sub-section, the first common section, the second sub-section, and the second common section in this order.

For example, in some embodiments, the current in the first sub-section is in the same direction as the current in the first portion, the first movable contact is elongated, and the first stationary contact and the first sub-section are located on opposite sides of the first movable contact. The current in the second subsection has the same direction as the current in the second part, the second movable contact is long, and the second fixed contact and the second subsection are located on opposite sides of the second movable contact.

For example, in some embodiments, the at least one common section is one common section configured to be connected to the load. The first load end of the first movable contact is connected to the load via the first sub-section and the common section in turn. The second load end of the first movable contact is connected to the load via the second sub-section and the common section in turn.

For example, in some embodiments, the current in the first sub-section and the current in the first portion are in opposite directions, the first movable contact is elongated, and the first stationary contact and the first sub-section are located on the same side of the first movable contact. The current in the second subsection is opposite to the current in the second part in direction, the second movable contact is long, and the second fixed contact and the second subsection are located on the same side of the second movable contact.

For example, in some embodiments, the at least one first sub-section is two or more first sub-sections. The conductor includes a helically extending first conductor portion including two or more turns, each of the two or more turns including one of the first sub-segments. The at least one second sub-section is two or more second sub-sections. The conductor also includes a helically extending second conductor portion including two or more turns, each of the two or more turns including one of the second sub-segments.

For example, in some embodiments, the first movable contact is at a distance in the range of-1-3 mm from the first portion when the first movable contact is in the first closed position. The second movable contact is located at a distance in the range of-1-3 mm from the second section when the second movable contact is in the second closed position.

For example, in some embodiments, the first movable contact is at a distance in the range of 0.1-2mm from the first portion when the first movable contact is in the first closed position. The second movable contact is located at a distance in the range of 0.1-2mm from the second section when the second movable contact is in the second closed position.

For example, in some embodiments, the first movable contact is at a distance in the range of-1-0 mm from the first portion when the first movable contact is in the first closed position. The second movable contact is located at a distance in the range of-1-0 mm from the second section when the second movable contact is in the second closed position.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present disclosure, and therefore should not be considered as limiting the scope of protection, and for those skilled in the art, other related drawings may be obtained from the drawings without inventive effort.

Fig. 1 shows a schematic plan view of a power switch according to an embodiment of the present disclosure;

fig. 2 shows a schematic plan view of a power switch according to another embodiment of the present disclosure;

FIG. 3 shows a perspective schematic view of a first conductor section of the power switch of FIG. 2;

fig. 4 shows an exploded perspective schematic view of the first conductor section of the power switch of fig. 2.

List of reference numerals

First

stationary contact

110, 210

First

movable contact

120, 220

Second

stationary contact

150, 250

Second

movable contact

160, 260

Pin 121

Moving contact support 122

First pigtail

130, 230

Second pigtail

170, 270

Conductors

140, 240

The

first sub-section

141, 241

The

second sub-section

142, 242

The third sub-section 143

The fourth sub-section 144

First common section 145

Second common section 146

Common section 243

First turn 244

Second turn 245

Connecting sub-section 246

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present disclosure more apparent, the technical solutions of the embodiments of the present disclosure will be described clearly and completely with reference to the drawings of the embodiments of the present disclosure. It is to be understood that the described embodiments are only a few embodiments of the present disclosure, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the disclosure without any inventive step, are within the scope of protection of the disclosure.

Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. "upper", "lower", "left", "right", etc. are used merely to indicate relative positioning, and when the absolute positioning of the object being described is changed, the relative positioning may also be changed accordingly.

Fig. 1 shows a schematic plan view of a power switch according to an embodiment of the present disclosure. As shown in fig. 1, the power switch is a dual power transfer switch, which has a first fixed contact 110 and a first movable contact 120 that are engaged with each other, and a second fixed contact 150 and a second movable contact 160 that are engaged with each other. The present disclosure is not so limited and the power switch may be other types of power switches. For example, the power switch may have only one pair of contacts, for example, the first stationary contact 110 and the first movable contact 120, which are mated with each other.

Referring back to fig. 1, the first stationary contact 110 is configured to be connected to a first power source, and the second stationary contact 150 is configured to be connected to a second power source. The first movable contact 120 is configured to rotate about a first pivot axis and is movable between a first closed position and a first open position. In the first closed position, the first contact end of the first movable contact 120 is in electrical contact with the first stationary contact 110. In the first open position, the first movable contact 120 is separated from the first stationary contact 110. The second movable contact 160 is configured to rotate about a second pivot axis and is movable between a second closed position and a second open position. In the second closed position, the second contact end of the second movable contact 160 is in electrical contact with the second stationary contact 150. In the second open position, the second movable contact 160 is separated from the second stationary contact 150. In fig. 1, the first movable contact 110 is in a first closed position and the second movable contact 160 is in a second open position. Taking the first movable contact 110 as an example, the first movable contact is pivotally mounted to the movable contact bracket 122 by a pin 121 so as to be rotatable about a first pivot axis located at the pin 121. The second movable contact 160 may be similarly mounted.

In addition, the power switch further comprises a conductor 140 configured to connect the first movable contact 120 and the second movable contact 160, respectively, to a load. Thus, when the first movable contact 120 is in the first closed position, it establishes an electrical circuit connection from the first power source to the load, and when the first movable contact 120 is in the first closed position, it breaks the electrical circuit connection from the first power source to the load. And, when the second movable contact 160 is in the second closed position, it establishes an electrical circuit connection from the second power source to the load, and when the second movable contact 160 is in the second closed position, it breaks the electrical circuit connection from the second power source to the load. For example, the first power supply may be a mains power supply and the second power supply may be a backup power supply. The dual power transfer switch can switch from the mains power supply to the backup power supply to continuously supply power to the load when the mains power supply fails to supply power to the load normally. For example, for live and neutral wires, a first power source is disconnected from a load, and then a second power source is connected to the load. For example, for a neutral line, the circuit connection between the second power source and the load is established and then the circuit connection between the first power source and the load is broken, i.e. an overlapping switching of the neutral line. Embodiments of the present disclosure are particularly applicable to, but not limited to, overlapping switching of neutral lines.

The conductor 140 is electrically connected to a first load end of the first movable contact 120 opposite the first contact end and is also connected to a second load end of the second movable contact 160 opposite the second contact end. Since the first movable contact 120 and the second movable contact 160 are movable, the conductor 140 is connected to the first movable contact 120 and the second movable contact 160 through a flexible connection such as the first wire shunt 130 and the second wire shunt 170, respectively.

The conductor 140 includes a first sub-section 141, the first sub-section 141 being disposed proximate to and extending generally along a first portion of the first movable contact 120 between the first load end and the first pivot axis. In the present embodiment, the first movable contact 120 is elongated, and the first fixed contact 110 and the second sub-section 142 are located on opposite sides of the first movable contact 120 (i.e., on the left side and the right side of the first movable contact 120, respectively). Also, when the first movable contact 120 is in the first closed position, the current in the first sub-section 141 is in the same direction as the current in the first portion. Therefore, when the first movable contact 120 is in the first closed position, the first sub-section 141 will apply an electrodynamic attractive force to the first portion of the first movable contact 120, thereby applying a torque that pivots the first movable contact 120 counterclockwise to bias the first contact end of the first movable contact 120 toward the first stationary contact 110. The larger the current, the larger the electrodynamic attraction force. Therefore, the contact between the first movable contact 120 and the first fixed contact 110 is reliably maintained, and the short-time current endurance of the power switch is improved.

The conductor 140 also includes a second sub-section 142, the second sub-section 142 being disposed proximate to and extending generally along a second portion of the second movable contact 160 between the second contact end and the second pivot axis. The second stationary contact 150, the second movable contact 160, and the second sub-section 142 are similarly and symmetrically configured and arranged as the first stationary contact 110, the first movable contact 120, and the first sub-section 141. The contact between the second movable contact 160 and the second stationary contact 150 is reliably maintained, which improves the short-time current endurance of the power switch.

In the present embodiment, most of the conductor including the first sub-section 141 and the second sub-section 142 is disposed between the first movable contact 120 and the second movable contact 160, which is beneficial to make the layout of the power switch compact and reduce the volume occupied by the power switch.

For example, the first sub-section 141 may be at a distance from the first part in the range of-1-3 mm, preferably in the range of 0.1-2mm, preferably 0.5 mm. Similarly, the second sub-section 142 may be at a distance from the second portion in the range of-1-3 mm, preferably in the range of 0.1-2mm, preferably 0.5mm, for example.

In addition, the conductor 140 includes a third sub-section 143, a fourth sub-section 144, a first common section 145, and a second common section 146. The first and second

common sections

145 and 146 connect the first and

second subsections

141 and 142, and the second common section 146 connects to a load. The first load end of the first movable contact 120 is connected to the third sub-section 143, the first common section 145, the first sub-section 141 and the second common section 146 in sequence, and the second load end of the second movable contact 160 is connected to the fourth sub-section 144, the first common section 145, the second sub-section 142 and the second common section 146 in sequence. The dashed line in fig. 1 shows the flow direction of a part of the current when the first contact end of the first movable contact 120 is in contact with the first stationary contact 110. The current flows to the first movable contact 120 via the first stationary contact 110, then flows to the first common section 145 via the first pigtail 130, the third subsection 143, then about 50% of the current flows to the first and

second subsections

141 and 142, respectively, and finally converges to the second common section 146 and flows to the load.

In the present embodiment, the resistance of the current path from the first load end of the first movable contact 120 to the load via the third sub-section 143, the first common section 145, the first sub-section 141 and the second common section 146 is designed to coincide with the resistance of the current path from the second load end of the second movable contact 160 to the load via the fourth sub-section 144, the first common section 145, the second sub-section 142 and the second common section 146. Thus, the electrodynamic attraction force is uniform for both pairs of contacts. The present disclosure is not limited thereto.

Fig. 2 shows a schematic plan view of a power switch according to another embodiment of the present disclosure.

As shown in fig. 2, the power switch is a dual power transfer switch, which has a first fixed contact 210 and a first movable contact 220 coupled with each other, and a second fixed contact 250 and a second movable contact 260 coupled with each other. The first stationary contact 210 is configured to be connected to a first power source and the second stationary contact 250 is configured to be connected to a second power source. The present disclosure is not so limited and the power switch may be other types of power switches. For example, the power switch may have only one pair of contacts, for example, a first stationary contact 210 and a first movable contact 220 that mate with each other.

The first movable contact 220 is configured to rotate about a first pivot axis and is movable between a first closed position and a first open position. In the first closed position, the first contact end of the first movable contact 220 is in electrical contact with the first stationary contact 210. In the first open position, the first movable contact 220 is separated from the first stationary contact 210. The second movable contact 260 is configured to rotate about a second pivot axis and is movable between a second closed position and a second open position. In the second closed position, the second contact end of the second movable contact 260 is in electrical contact with the second stationary contact 250. In the second open position, the second movable contact 260 is separated from the second stationary contact 250. In fig. 2, the first movable contact 220 is in a first closed position and the second movable contact 260 is in a second open position.

Furthermore, the power switch comprises a conductor 240 configured to connect the first movable contact 220 and the second movable contact 260, respectively, to a load. Specifically, the conductor 240 is electrically connected to a first load end of the first movable contact 220 opposite the first contact end and a second load end of the second movable contact 260 opposite the second contact end through flexible connections, such as a first wire pigtail 230 and a second pigtail 270, respectively.

The conductor 240 includes a first sub-section 241, the first sub-section 241 being disposed proximate to and extending generally along a first portion of the first movable contact 220 between the first load end and the first pivot axis. In the present embodiment, the first movable contact 220 is elongated, and the first fixed contact 210 and the second sub-section 242 are located on the same side (i.e., the left side) of the first movable contact 220. Also, when the first movable contact 220 is in the first closed position, the current in the first sub-section 241 is in the opposite direction to the current in the first portion. Thus, when the first movable contact 220 is in the first closed position, the first sub-section 241 will apply an electrically-driven repulsive force to the first portion of the first movable contact 220, thereby applying a torque that pivots the first movable contact 220 counterclockwise to bias the first contact end of the first movable contact 220 toward the first stationary contact 210. The larger the current, the larger the electrodynamic repulsion. Therefore, the contact between the first movable contact 220 and the first fixed contact 210 is reliably maintained, and the short-time current tolerance of the power switch is improved.

The conductor 240 further includes a second sub-section 242, the second sub-section 242 being disposed proximate to and extending generally along a second portion of the second movable contact 260 between the second contact end and the second pivot axis. The second stationary contact 250, the second movable contact 260, the second sub-section 242 are similarly and symmetrically configured and arranged as the first stationary contact 210, the first movable contact 220, and the first sub-section 241. The contact between the second movable contact 260 and the second stationary contact 250 is reliably maintained, which improves the short-time current endurance of the power switch.

In this embodiment, the conductor 240 further includes a common section 243. The common section 243 connects the first and

second subsections

241, 242 and is connected to a load. The first load end of the first movable contact 220 is connected to the first wire pigtail 230, the first sub-section 241, and the common section 243 in that order to be connected to a load, and the second load end of the second movable contact 260 is connected to the second wire pigtail 270, the second sub-section 242, and the common section 243 in that order to be connected to a load. The dashed line in fig. 2 shows the flow direction of a part of the current when the first contact end of the first movable contact 220 is in contact with the first stationary contact 210. The current flows via the first stationary contact 210 to the first movable contact 220, then flows through the first wire pigtail 230 to the first sub-section 241, and finally to the common section 243 and into the load.

Taking the first movable contact 220 and the first fixed contact 210 as an example, since only one common section 243 is provided, the current is not shunted in the flow path from the first fixed contact 210 to the common section 243 via the first movable contact 220, the first sub-section 241, and the first fixed contact 210. Substantially all of the current may flow to the first sub-section 241 for generating greater electrodynamic repulsion forces. Therefore, the requirement for a gap between the first sub-section 241 and the first portion of the first movable contact 220 is reduced. For example, the distance of the first sub-section 241 from the first portion may be in the range of-1-3 mm. Further, the distance of the first sub-section 241 from the first part may be in the range of 0.1-2 mm. Here, the distance is a negative number to indicate that the first sub-section 241 overlaps the first portion as long as the first sub-section 241 can apply an electromotive force to the first portion to bias the first contact end of the first movable contact 220 toward the first stationary contact 210. For example, the distance of the first sub-section 241 from the first portion may be in the range of-1-0 mm. Such a distance arrangement helps to reduce the size of the electric switch and facilitates the layout of other components in the electric switch. The distance of the second sub-section 242 from the second portion may be similarly configured.

Further, the conductor 240 may include a plurality of first subsections 241 and a plurality of second subsections 242. Fig. 3 shows a perspective schematic view of the first conductor part of the power switch in fig. 2, and fig. 4 shows an exploded perspective schematic view of the first conductor part of the power switch in fig. 2.

As shown in fig. 2-4, in the present embodiment, conductor 240 includes a first conductor portion. The first conductor portion extends helically and includes two turns (i.e., a first turn 244 and a second turn 245), each turn including one first sub-section 241. I.e. the first conductor part comprises two first sub-sections 241. It will be understood by those skilled in the art that the first conductor portion may also include more turns, and thus more first sub-sections 241. As shown in fig. 2-4, the first turn 244 and the second turn 245 may be connected together by a connector (not shown), such as a screw, such that the first conductor portion extends helically. Specifically, the first turn 244 and the second turn 245 are ring shapes having a gap, the first pigtail 230 is connected to one end of the first turn 244, the other end of the first turn 244 is connected to one end of the second turn 245 by a connector, and the other end of the second turn 245 is connected to the common section 243 via the connector section 246. The dashed line a-a 'in fig. 4 shows the flow of current in the first turn 244 and the dashed line B-B' in fig. 4 shows the flow of current in the second turn 245. As shown in fig. 4, the current flows in a spiral path in the first conductor portion via the first turn 244 and the second turn 245, and then to the connecting sub-section 246. In this process, current flows through the first sub-section 241 in the first turn 244 and the first sub-section 241 in the second turn 245, respectively. Since the conductor 240 includes a plurality of first subsections 241, therefore, a greater electrodynamic force is generated, the ability of the power switch to maintain contact between the first movable contact 220 and the first stationary contact 210 is enhanced, and the requirement for a gap between the first subsections 241 and the first portion of the first movable contact 220 is reduced.

Similarly and substantially symmetrically, the conductor 240 also includes a second conductor portion that includes two turns, each turn including a second sub-section 242. The current flows in a spiral path through two turns of the second conductor portion in turn. In this process, current flows through the second subsection 242 of the two turns, respectively. Since the conductor 240 includes a plurality of second subsections 242, a greater electrodynamic force is generated, the ability of the power switch to maintain contact between the second movable contact 260 and the second stationary contact 250 is enhanced, and the requirement for a gap between the second subsections 242 and the first portion of the second movable contact 260 is reduced.

Further, for example, in a direction perpendicular to the plane of the first turn 244 and the second turn 245 of the first conductor portion, the first portion of the first movable contact 241 may be disposed between the first sub-section 241 in the first turn 244 and the second sub-section 241 in the second turn 245. In this way, it is possible to contribute to reduction in size of the electric switch, convenience in layout of other components of the electric switch, and provision of stable and balanced electric power. Similarly, in a direction perpendicular to the plane of the two turns of the second conductor portion, the second portion of the second movable contact 242 may be disposed between the first subsections 241 of the two turns.

In the present embodiment, the resistance of the current path from the first load end of the first movable contact 220 to the load via the first sub-section 241 and the common section 243 is designed to coincide with the resistance of the current path from the second load end of the second movable contact 260 to the load via the second sub-section 242 and the common section 243. Thus, the electrodynamic attraction force is uniform for both pairs of contacts. The present disclosure is not limited thereto.

The scope of the present disclosure is not defined by the above-described embodiments but is defined by the appended claims and equivalents thereof.

Claims

1. A power switch, comprising:

a first stationary contact configured to be connected to a first power source;

a first movable contact configured to rotate about a first pivot axis and movable between a first closed position in which a first contact end of the first movable contact is in electrical contact with the first stationary contact and a first open position in which the first movable contact is separated from the first stationary contact; and

a conductor configured to connect a first load end of the first movable contact opposite the first contact end to a load and including at least one first sub-section disposed proximate to and extending generally along a first portion of the first movable contact between the first load end and the first pivot axis such that an electromotive force resulting from current in the first sub-section and current in the first portion biases the first contact end of the first movable contact toward the stationary first contact when the first movable contact is in the first closed position.

2. The power switch of claim 1,

the at least one first sub-section is two or more first sub-sections,

the conductor includes a helically extending first conductor portion including two or more turns, each of the two or more turns including one of the first sub-segments.

3. The power switch of claim 1,

the at least one first sub-section is two first sub-sections,

the conductor comprising a helically extending first conductor portion comprising two turns, each of the two turns comprising one of the first sub-sections,

the first portion of the first movable contact is arranged between two first subsections of the two turns in a direction perpendicular to the plane of the two turns.

4. The power switch of claim 1,

the first movable contact is located at a distance in the range of-1-3 mm from the first section when the first movable contact is in the first closed position.

5. The power switch of claim 1,

the first movable contact is located at a distance in the range of 0.1-2mm from the first section when the first movable contact is in the first closed position.

6. The power switch of claim 1,

the first movable contact is located at a distance in the range of-1-0 mm from the first section when the first movable contact is in the first closed position.

7. The power switch of claim 1,

the power switch is a dual power transfer switch, and further comprises:

a second stationary contact configured to be connected to a second power supply; and

a second movable contact configured to rotate about a second pivot axis and movable between a second closed position in which a second contact end of the second movable contact is in electrical contact with the second stationary contact and a second open position in which the second movable contact is separated from the second stationary contact,

the conductor is further configured to connect a second load end of the second movable contact opposite the second contact end to the load, and further includes:

at least one second sub-section disposed proximate to and extending generally along a second portion of the second movable contact between the second load end and the second pivot axis such that when the second movable contact is in the second closed position, electromotive force resulting from current in the second sub-section and current in the second portion biases the second contact end of the second movable contact toward the second stationary contact; and

at least one common section connecting the at least one first sub-section and the at least one second sub-section, and one of the at least one common section is configured to be connected to the load.

8. The power switch of claim 7,

the conductor further includes a third sub-section and a fourth sub-section,

the at least one common section comprises a first common section and a second common section configured to be connected to the load,

the first load end of the first movable contact is connected to the load via the third sub-section, the first common section, the first sub-section and the second common section in this order,

the second load end of the second movable contact is connected to the load via the fourth sub-section, the first common section, the second sub-section, and the second common section in this order.

9. The power switch of claim 7,

the current in the first subsection has the same direction as the current in the first part, the first movable contact is long, the first fixed contact and the first subsection are positioned on the opposite sides of the first movable contact,

the current in the second subsection has the same direction as the current in the second part, the second movable contact is long, and the second fixed contact and the second subsection are located on opposite sides of the second movable contact.

10. The power switch of claim 7,

the at least one common section is one common section configured to be connected to the load,

the first load end of the first movable contact is connected to the load via the first sub-section and the common section in turn,

the second load end of the first movable contact is connected to the load via the second sub-section and the common section in turn.

11. The power switch of claim 7,

the current in the first subsection and the current in the first part are opposite in direction, the first movable contact is long, the first fixed contact and the first subsection are positioned on the same side of the first movable contact,

the current in the second subsection is opposite to the current in the second part in direction, the second movable contact is long, and the second fixed contact and the second subsection are located on the same side of the second movable contact.

12. The power switch of claim 7,

the at least one first sub-section is two or more first sub-sections,

the conductor includes a helically extending first conductor portion including two or more turns, each of the two or more turns including one of the first sub-sections,

the at least one second sub-section is two or more second sub-sections,

the conductor also includes a helically extending second conductor portion including two or more turns, each of the two or more turns including one of the second sub-segments.

13. The power switch of claim 7,

the first movable contact is located at a distance in the range of-1-3 mm from the first section when the first movable contact is in the first closed position,

the second movable contact is located at a distance in the range of-1-3 mm from the second section when the second movable contact is in the second closed position.

14. The power switch of claim 7,

the first movable contact is in the first closed position, the first sub-section is at a distance in the range of 0.1-2mm from the first section,

the second movable contact is located at a distance in the range of 0.1-2mm from the second section when the second movable contact is in the second closed position.

15. The power switch of claim 7,

the distance of the first sub-section from the first section is in the range of-1-0 mm when the first movable contact is in the first closed position,

the second movable contact is located at a distance in the range of-1-0 mm from the second section when the second movable contact is in the second closed position.