GB2580594A

GB2580594A - Generator terminal board

Info

Publication number: GB2580594A
Application number: GB1900468.8A
Authority: GB
Inventors: Walker Jack; Ilie Sorin; Narayanan Sridhar; Vucenovic Marko; Haider Ali Abbas
Original assignee: Cummins Generator Technologies Ltd
Current assignee: Cummins Generator Technologies Ltd
Priority date: 2019-01-14
Filing date: 2019-01-14
Publication date: 2020-07-29
Also published as: CN211321101U; GB2580594A8; GB201900468D0

Abstract

A terminal board 40 for an electric generator comprises a base 42 and a plurality of studs 44,45 extending out of the base and arranged in a two-dimensional array. The studs may connect end leads from generator windings to generator output terminals, or the studs may be connected to each other. The studs may be arranged such that the generator windings can be configured in a plurality of different connection arrangements, such as a star arrangement or a delta arrangement, which may be done without moving the end leads. The studs may be arranged in at least three rows, wherein one row may be used for generator output terminals. The studs may extend out of bosses 48,49 in the base. The bosses may have at least two different heights to allow electrical connections to studs and/or between studs to be made at two different distances from the plane of the base. The base may comprise studs of at least two different lengths. The number of studs may exceed the number required for a single connection arrangement. The terminal board allows for the connection arrangement of a generator to be changed by reconfiguring the links between the studs and/or moving one or more of the end leads.

Description

GENERATOR TERMINAL BOARD

The present invention relates to a terminal board for an electrical generator, and in particular a terminal board which can facilitate configuration of the generator in a plurality of different connection arrangements.

Electrical generators generally comprise stator windings which interact with a rotating magnetic field to generate an AC output. The rotating magnetic field is usually produced by a rotor which carries rotor windings or permanent magnets.

The stator windings normally comprise a number of coils disposed in slots circumferentially about a stator core. The coils typically have coil end leads which are used for connection purposes. The end leads are usually brought to a common connection point such as a terminal box. A terminal board in the terminal box may be used to connect the coil end leads to the appropriate generator output terminal.

In the case of a multi-phase machine, there may be a number of different arrangements in which the coils can be connected, such as star and delta connection arrangements. In this case, the terminal board may also be used to configure the stator coils in the required connection arrangement.

Electrical generators are usually supplied with the coils pre-configured in the required connection arrangement. However in some circumstances it may be desirable to change the connection arrangement at a later date. With current arrangements this may be difficult to achieve. Furthermore, there is a danger than an inexperienced user could connect the generator incorrectly, which could be dangerous and/or result in damage to the machine.

It would therefore be desirable to provide a terminal board which can allow easy reconfiguration of the generator connection arrangement while minimising the risk of incorrect connections being made.

According to one aspect of the present invention there is provided a terminal board for an electrical generator, the terminal board comprising a base and a plurality of studs which extend out of the base, wherein the studs are arranged in a two-dimensional array.

The present invention may provide the advantage that, by providing a terminal board comprising a base and a plurality of studs arranged in a two-dimensional array, re-configuration of the generator connection arrangement can be facilitated and/or the risk of misconnection reduced.

By two-dimensional array it is preferably meant that a plurality of studs are provided in each of a first and a second direction. The first and second directions may be orthogonal to each other and/or orthogonal to a longitudinal direction of the studs (which may be the direction in which the studs extend out of the base).

The studs are preferably arranged to allow electrical connections to be made by receiving electrical connectors such as lugs and/or links. The studs may be made from an electrically conductive material such as a metal. The studs may be in the form of, for example, cylindrical posts. The studs may be threaded along at least part of their length, which may allow electrical connectors to be secured to the studs by screwing a bolt onto the stud. The base is preferably made from an electrically non-conductive material, such as a plastic (for example, glass reinforced plastic, fibreglass reinforced polyester) or any other suitable material.

Preferably the studs are arranged to connect end leads from generator windings to generator output terminals and/or to each other. This can allow the terminal board to connect the windings in different connection arrangements as well as connecting the end leads to output terminals.

The electrical generator is preferably a multiphase machine, such as a three-phase machine. In this case the generator windings may comprise at least two coils per phase. The end leads are preferably end leads of the coils.

Preferably the studs are arranged such that the windings can be configured in a plurality of different connection arrangements. The plurality of different connection arrangements may comprise at least one of a star connection arrangement and a delta connection arrangement. In one embodiment, the plurality of different connection arrangements comprise two or more of: series star; parallel star; series delta; double delta; and parallel delta. However other connection arrangements are also possible.

In one embodiment, the studs are arranged such that the generator windings can be configured in a plurality of different connection arrangements without moving the end leads. This may be achieved, for example, by reconfiguring links between the studs and/or spacers on the studs. However it may also be possible to reconfigure the connection arrangement by moving one or more of the end leads as well or instead.

Preferably the total number of studs exceeds the number of studs which is required for any single connection arrangement. Thus, some studs may be used for some connection arrangements but not others. This may facilitate re-configuration of the windings in a plurality of different connections arrangements.

In one embodiment, the studs are arranged in three (or more) rows, with a plurality of studs in each row. In this case, one row of studs may be used for generator output terminals. The generator output terminals may be formed from lugs (such as L-shaped lugs) which may be connected to one or more of the studs. Some or all of the rows may be used to receive end leads from the generator windings, in order to connect those end leads to each other and/or to generator output terminals. Such an arrangement may provide flexibility in how the windings are connected and thus may facilitate re-configuration in a plurality of different connections arrangements.

In one embodiment, three rows of studs are provided, with eight studs in a first row, six studs in a second row, and five studs in a third row. However a different number of studs may be provided, and each row may have more or fewer studs than the number given. Furthermore, a different number of rows may be provided, such as two rows, four rows, or some other number.

The base may have an upper surface, and the studs may extend out of the plane of the upper surface. Preferably the upper surface extends in first and second directions which may be orthogonal to a longitudinal direction of the studs and/or to each other.

The base is preferably substantially flat. Thus the base may have a height which is small in comparison to the dimensions of the upper surface (i.e. the length of the upper surface in the first and second directions). For example, the length of the upper surface in the first and/or second direction may be at least 2, 5 or 10 times the height of the base, or some other value.

The terminal board is preferably arranged to be mounted on the generator. For example, the base of the terminal board may comprise a plurality of holes which allow it to be attached to a part of the generator, for example, using bolts or studs. For example, the terminal board may be mountable on mounting brackets on a frame of the generator. The terminal board may be, for example, housed in a terminal box or housed with terminal panels.

Preferably the terminal board is arranged to mount onto the generator such that the base (and/or its upper surface) extends in a first direction which is parallel to an axis of the generator, and a second direction which is tangential to a circumference of the generator (relative to the axis of rotation). At least some of the studs may extend in a direction which is parallel to a radial direction (relative to the axis of rotation). For example, when mounted on the generator, the base and/or its upper surface may face upwards and/or be substantially horizontal. In this case, the studs may be substantially vertical. This may facilitate connection of the winding end leads, since it may allow the terminal board to be easily viewed and/or accessed from a single direction, such as from above. However it would also be possible for the terminal board to be mounted at an angle to the horizontal.

Preferably the terminal board is arranged such that it can receive end leads from the generator on two different sides, such as two opposite sides. For example, the end leads may be brought through an aperture, holes or glands in a generator frame and to the terminal board on either side of the terminal board. This may facilitate re-configuration of the generator connection arrangement.

Preferably the base comprises a plurality of bosses, and the studs extend out of the bosses. The bosses may be, for example, protrusions which protrude out of a plane of an upper surface of the base. For example, the bosses may protrude out of the upper surface in the same direction as a longitudinal direction of the studs (which is preferably the direction in which the studs extend out of the base).

The bosses may help to support the studs and/or they may provide a shoulder against which an electrical connector (which is connected to the corresponding stud) can rest. The bosses may be arranged such that when an electrical connector (such as lug) is connected to a stud it rests directly or indirectly on a boss. For example, an electrical connector lug may rest directly on a boss, or may sit on top of one or more washers which sit on the boss.

In a preferred embodiment of the invention, the terminal board comprises bosses of at least two different heights, or at least three different heights. The height may be for example the amount by which a boss protrudes out of an upper surface of the base. This can allow electrical connectors which are connected to the studs to lie in one of two (or more) different planes, depending on the height of the boss out of which the stud extends. Thus, the bosses may allow electrical connections to studs and/or between studs to be made at two or three different distances from a plane of an upper surface of the base. This may help to ensure that only certain connections between studs can be made, thereby reducing the risk of misconnection.

Furthermore, allowing connections to be made at two or three different heights may allow the terminal board to have connections to and/or between studs which overlap with each other, while ensuring sufficient electrical separation between those connections and/or sufficient clearance as defined in the relevant standards. This may therefore facilitate configuration of the windings in a plurality of different connection arrangements. Preferably a different in height between two bosses of two different heights is such as to ensure sufficient electrical separation and/or clearance between different phases of a generator with which the terminal board is to be used.

The terminal board may comprise studs of at least two different lengths. For example, the studs may have 2, 3, 4 or more different lengths. The length may be, for example, the amount by which the stud extends out of a corresponding boss in a longitudinal direction (which may be orthogonal to a plane of an upper surface of the base). For example, in one possible arrangement, a stud which extends out of a boss which is at the lower of two heights may have either of two (or more) different lengths, while the studs which extend out of a boss with the greater of the two heights may have the shorter of the two (or more) lengths.

The longer studs may allow electrical connections to be made at two different distances from a plane of an upper surface of the base. On the other hand, the shorter studs may allow electrical connections to be made at only one of the two different distances. This may help to ensure that only certain connections between studs can be made, and thus may help to ensure that the terminal board is not misconnected.

In the case of a longer stud, an electrical connection may be made at (the greater) one of the two different distances from a plane of an upper surface of the base by placing a removable spacer on the stud. In this case, an electrical connection at the other of the two distances may be made by using the stud without a spacer. The spacer may be, for example, in the form of a collar which can be placed on a stud. For example, the spacer may be a disc of material with a hole which allows it to be placed on a stud. The spacer be made from an electrically conductive material such as copper or another suitable metal.

Preferably at least some of the studs are interconnectable by means of a rigid link. A rigid link may comprise an electrical conductor with a hole or slot at each end which allows the link to connect to a stud. The link may be made from copper or any other suitable conducting material. Use of such rigid links may allow the connection arrangement to be changed by reconfiguring the links (e.g. by adding, removing or moving one or more of the links). This may facilitate reconfiguration of the generator windings in a different connection arrangement.

A rigid link may have a predefined length. This may allow a link to connect two studs with a predefined distance between them, but not two studs with another distance between them. This may help to ensure that the terminal board is not misconnected.

For example, at least some of the studs may be arranged in pairs, and a pair of studs may be interconnectable by means of a rigid link. For example, where the studs are arranged in rows, at least some of the studs of a row may be arranged in pairs. Arranging the studs in pairs may help to ensure that the correct connections are made. The studs in a pair may share a common boss or have bosses of the same height, although other arrangements are also possible.

In one embodiment, three rows of studs are provided, with four pairs of studs in a first row, three pairs of studs in a second row, and three individual studs and one pair of studs in a third row. However a different number of studs and/or pairs may be provided, and in some cases there may be a single stud rather than a pair of studs.

Preferably, the studs of at least one pair are separated from each other by a different distance than the studs of at least one other pair. Thus, the studs of at least one pair may be connectable using a rigid link of a first length, and the studs of least one other pair may be connectable using a rigid link of a second length different from the first. This may constrain the different connections that can be made, thereby helping to ensure that the terminal board is not misconnected. Connections between pairs of studs may also be possible using links of an appropriate length.

The terminal board may comprise ribs in its upper surface. The ribs may indicate to a user where a link should be placed, for example, for a certain connection arrangement.

According to another aspect of the invention there is provided a terminal board assembly comprising a terminal board in any of the forms described above, and a plurality of rigid links for connecting studs on the terminal board. Preferably the plurality of rigid links comprises at least one rigid link of a first length, and at least one rigid link of a second length different from the first. The terminal board assembly may further comprise at least one removable spacer, which may function to space an electrical connector along a stud away from an upper surface of the base.

According to another aspect of the invention there is provided an electrical generator comprising a terminal board or terminal board assembly in any of the forms described above.

According to a further aspect of the invention there is provided a method of reconfiguring a connection arrangement of windings in an electrical generator, the electrical generator comprising a terminal board comprising a base and a plurality of studs which extend out of the base, the method comprising reconfiguring a connection arrangement by reconfiguring links between the studs and/or moving one or more end leads of the windings. Preferably the studs are arranged in a two-dimensional array.

Features of one aspect of the invention may be provided with any other aspect. Apparatus features may be provided with method aspects and vice versa.

In the present disclosure, terms such as "radial", "axial" and "circumferential" are preferably defined with reference to the axis of rotation of the electrical generator, unless the context implies otherwise.

Preferred embodiments of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded view of parts of a known electrical generator; Figure 2 illustrates schematically the stator windings in a three phase machine with two stator coils per phase; Figures 3A to 3C illustrate some of the connection arrangements which are possible with the stator coils shown in Figure 2; Figure 4 shows parts of a terminal board in an embodiment of the invention; Figures 5A to 5C illustrate two links and a collar which may be used to connect end leads of stator coils; Figure 6 shows how end leads from the stator windings are connected to a terminal board in one embodiment of the invention; Figures 7 through 9 illustrate how stator windings can be connected in various different connection arrangements in the embodiment of Figure 6; Figures 10 through 13 illustrate how stator windings can be connected in various different connection arrangements in another embodiment of the invention; and Figures 14 through 17 show parts of a terminal board in another embodiment of the invention.

Figure 1 is an exploded view of parts of a known electrical generator. The generator 10 comprises main frame 12 mounted on feet 14. A stator core 16 is located inside the main frame 14. The stator core 16 is wound with stator windings 18. In the assembled machine a rotor is located inside the stator, although this is omitted in Figure 1 for clarity.

In a generator such as that shown in Figure 1, the stator normally acts as the armature and carries the main electrical output power. It is therefore necessary to connect the stator windings to generator output terminals. In the arrangement shown, this is achieved by bringing end leads 20 from the stator windings 18 through an aperture 22 in the main frame to a terminal board 24. The terminal board 24 is used to connect the end leads to the appropriate generator output terminal and/or to each other. The terminal board is housed inside a terminal box 26, comprising end panels 27, 28, side panels 29, 30, and a lid 31.

In the arrangement of Figure 1, the terminal board comprises a plurality of upright metal bars 32 to which the end leads 20 can be connected using lugs. The metal bars 32 are connected at their upper ends to U-shaped metal bars 34 which form the generator output terminals. Additional metal bars may be provided for connecting coil end leads which are not to be connected directly to an output terminal. In addition, an automatic voltage regulator (AVR) 36 may be connected to some or all of the output terminals via an electrical loom.

In the example shown in Figure 1, the generator is a three-phase generator, and the stator windings 18 comprise two coils per phase. Thus, a total of twelve end leads 20 (two from each coil) are brought from the stator windings 18 through the aperture 22 to the terminal board 24. The terminal board 24 comprises an output terminal for each of the three phases U, V, W, as well as a neutral terminal N. Figure 2 illustrates schematically the stator windings in a three phase machine with two stator coils per phase. In this example a total of twelve end leads are present, two from each coil. In Figure 2, the end leads from the U-phase coils are labelled Ul, U2, U5 and U6, the end leads from the V-phase coils are labelled V1, V2, V5 and V6, and the end leads from the W-phase coils are labelled W1, W2, W5, and W6.

Figures 3A to 3C illustrate some of the connection arrangements which are possible with the stator coils shown in Figure 2. A series star arrangement is shown in Figure 3A, a parallel star arrangement is shown in Figure 3B, and a series delta arrangement is shown in Figure 3C. The end leads of the coils are given the same labels as in Figure 2 to show how the coils are connected. It will be appreciated that other connection arrangements, such as double delta and parallel delta, are also possible.

Usually a three-phase generator such as that shown in Figure 1 is supplied to the user pre-configured with the appropriate connection arrangement for the application with which the generator is to be used. However, in certain situations such as the rental market, there may be a requirement to re-configure the connection arrangement after the generator has been supplied. This typically requires the end leads to be disconnected from the terminal board and then reconnected in a different configuration. Using known terminal boards, such reconfiguration may be cumbersome due to the need to move end leads from one place to another. Furthermore, such re-configuration may be prone to error, which could be dangerous and lead to damage to the generator and/or equipment to which it is connected.

Figure 4 shows parts of a terminal board in an embodiment of the invention. Referring to Figure 4, the terminal board 40 comprises a base 42 and a plurality of studs 44, 45. The base is generally flat, with a height which is small relative to its width and depth. The studs are in the form of threaded cylindrical posts. The studs 44, 45 extend out of bosses 48, 49 in the base. The base 42 comprises four sides 46, a top surface 47, and an underside (not visible in Figure 4). The bosses 48, 49 protrude out of the plane of the top surface 47 of the base. Each boss 48, 49 may have either a single stud or a pair of studs extending out of it.

Ribs 51 are provided between some of the bosses.

The base also includes four holes 50 which allow it to be mounted in the terminal box of a synchronous generator on a raised mounting brackets, one on the non-drive end of the machine and one on the drive end, either side of the aperture where the end leads from the stator come though. When mounted in this way, the base 42 is horizontal, with the top surface 47 facing upwards, and the studs 44, 45 extending vertically out of the base.

The base 42 is made from an electrically non-conducting material such as glass reinforced plastic (GRP). The base may be manufactured, for example, by compression moulding of a dough moulding compound (DMC). The studs 44, 45 are made from an electrically conductive material such as metal. The studs 44, 45 are designed to meet the appropriate standards for electrical connections, and allow end leads to be positioned onto them via terminal lugs. The studs are threaded, to allow bolts to be screwed on to secure the lugs or other components.

In the arrangement shown, the base 42 comprises two different types of boss. A first type of boss 48 has a first height (in a direction coming out of the plane of the top surface 47), while a second type of boss 49 has a second height which is higher than that of the first. When a connector such as a lug or a link is placed on a stud, it rests against the corresponding boss, optionally with a washer between the boss and the connector. As a consequence, such connectors may be at one of two different heights, depending on the height of the boss against which it rests. In other words, the connectors may lie in one of two different planes, each plane being parallel with the plane of the top surface 47 of the base 42.

In addition, the studs themselves have one of two or more different lengths (also in a direction coming out of the plane of the top surface). A first type of stud 44 has first length, while a second type of stud 45 has a second length which is greater than that of the first. All of the studs which extend out of a second type of boss 49 have the shorter of the two lengths. On the other hand, the studs which extend out of the first type of boss 48 may have either the shorter or the longer of the two lengths. The difference between the two lengths is approximately the same as the difference in height between the two types of boss. Thus, the total height of a long stud 45 extending out of a low boss 48 is approximately the same as the total height of a short stud 44 extending out of a high boss 49. However the total height of a short stud extending out of a low boss 48 is less than that of the other stud/boss combinations. Thus, the top of each short stud 44 lies in one of two different planes, each plane being parallel with the plane of the top surface 47 of the base 42.

In this embodiment, the terminal board comprises nineteen studs arranged in three rows: a front row 52, a middle row 53 and a rear row 54. The studs in the front row 52 are used for the generator output terminals U, V, W and N. A total of eight studs is provided in this row, with a pair of studs being used for each output terminal. The first three pairs of studs in this row (viewed from left to right in Figure 4) are used for the output terminals U, V and W. These three pairs of studs have bosses 48 which are at the lower of the two heights. Each of these pairs includes a first type of stud 44 with a first length, and a second type of stud 45 with a second length. The fourth pair of studs in the front row 52 is used for the neutral output terminal N. This pair of studs has a boss 49 which is at the higher of the two heights.

The studs in the middle row 53 are used for making connections between the coils in the stator windings and/or the output terminals. A total of six studs is provided in this row. The studs are provided in pairs, with each pair of studs having a boss 48 which is at the lower of the two heights. Each of these pairs includes a first type of stud 44 with a first length, and a second type of stud 45 with a second length. The distance between a pair of studs in the middle row 53 is greater than the distance between a pair of studs in the front row 52.

The studs in the rear row 54 are also used for making connections between the coils in the stator windings and/or the output terminals. A total of five studs is provided in this row. These studs have bosses 49 which are at the higher of the two heights. The first three studs in the rear row (viewed from left to right) are provided as individual studs rather than as pairs. The distances between these individual studs is greater than the distances between the two studs of a pair in either the middle row 53 or the front row 52. In the rear row 54, the final two studs are provided as a pair. This pair of studs may also be used for the neutral output terminal N. In an alternative embodiment, two additional studs are provided in the rear row for current transformer placement. Thus. in this alternative embodiment, a total of seven studs is provided in the rear row. It will be appreciated that other embodiments are also possible, with different numbers of studs in each row and/or a different number of rows.

In Figure 4, the locations of the studs 44, 45 are such as to allow different sized links to be placed onto them. Additionally, collars may be placed on the studs where appropriate to raise the level of the links. The position of the studs allows a quick and user-friendly configuration change of the leads coming up from the stator of the generator, while reducing the possibility of incorrect connections being made. The location of the studs and the length of the links allow the board readily to be configured in a plurality of different arrangements, such as: parallel star, series delta, series star, double delta and parallel delta.

Figures 5A to 5C illustrate two links and a collar which may be used to connect the end leads of the stator coils. The links 55, 56 shown in Figures 5A and 5B are electrically conductive metal links with holes at each end which allow them to be placed on the studs 44, 45 of Figure 4. The links 55, 56 have different lengths, each of which corresponds to the distance between two studs which may need to be connected. In the examples shown, the link 55 is 70mm long while the link 56 is 120mm long, although it will be appreciated that other lengths could be used as well or instead. The collar 58 of Figure 5C is an electrically conductive metal disc which can be placed on a stud in order to raise the level of a link.

In use, the links 55, 56 (and optionally a collar 58) are placed onto the studs and secured down with a washer, spring washer and nut which are tightened to the appropriate tension. The ribs 51 indicate to the user locations where it may be appropriate to place links for various different connection arrangements.

Figure 6 shows how the end leads 20 from the stator windings are connected to the terminal board 40 in one embodiment of the invention. In this embodiment, the machine is a three-phase machine with two coils per phase, and two end leads from each coil. The end leads from the stator coils are labelled using the same labelling convention as in Figure 2.

Figures 7 through 9 illustrate how the stator windings can be connected in various different connection arrangements when the end leads are connected to the terminal board in the way shown in Figure 6.

Figure 7 shows how the stator windings can be connected in a series star arrangement. in this arrangement, it is necessary to connect the end leads Ul, V1 and W1 to respective output terminals U, V, W; to connect the end leads U6, V6 and W6 to the neutral terminal N; and to connect the end leads U2, V2 and W2 respectively to U5, V5 and W5 (see Figure 3A).

In this embodiment, the middle row 53 of studs is used to connect the end leads U5 and U2 to each other, the end leads V5 and V2 to each other, and the end leads W5 and W2 to each other. This is achieved by connecting a short link 55 between the appropriate studs. These links are all at the lower of the two different levels. The rear row 54 of studs is used to connect the end leads U6, V6 and W6 to neutral. This is achieved by connecting long links 56 between the studs in the rear row, and connecting these studs to the studs in the neutral terminal using a short link 55. Since these links are all at a higher level, the end leads U2, U5, V2, V5, W2 and W5 can pass under the links to the middle row 53 with the necessary clearance. The front row of studs is used for the output terminals U, V, W and N. In this embodiment, a long link 56 is used to connect the studs in the rear row 54 to the neutral terminal in the front row 52.

The output terminals U, V, W and N are formed from L-shaped lugs 60. The L-shaped lugs 60 are formed from metal formed into an L-shape. Each L-shaped lug has two holes for connecting the lug to the appropriate stud 44, 45, and two holes which can be used by the user to connect the generator to a load.

Figure 8 shows how the stator windings can be connected in a parallel star arrangement. In order to move from the series star arrangement of Figure 7 to the parallel star arrangement of Figure 8, it is necessary to move the end leads U2, V2 and W2 to the neutral terminal, and the end leads U5, V5 and W5 to respective ones of the U, V and W terminals (see Figure 3B). In this embodiment, the short links between the studs in the middle row 53 are removed, thereby removing the series connections between the coils. In order to connect the end leads U2, V2 and W2 to the neutral terminal, collars 58 are placed on the appropriate studs in the middle row 53, and then short links 55 are placed between those studs and the studs in the rear row 54. The collars 58 raise the level of the links to that of those in the rear row. Since these links are at a higher level, the end leads U5, V5 and W5 can pass under the links to the middle row 53. The connection of the end leads U5, V5 and W5 to the respective U, V and W terminals is achieved by placing short links 55 between the appropriate studs in the middle row 53 and the appropriate output terminal. The output terminals are formed from L-shaped lugs 60 in the same way as those shown in Figure 7.

In the example shown in Figure 8, the neutral terminal is located in the rear row 54, although it could also be located in the front row 52 using a link 56 as shown in Figure 7.

Figure 9 shows how the stator windings can be connected in a series delta arrangement. In order to move from the series star arrangement of Figure 7 to the series delta arrangement of Figure 9, it is necessary to connect the end lead U6 to the V terminal, the end lead V6 to the W terminal, and the end lead W6 to the U terminal (see Figure 3C). In this embodiment, the links between the studs in the rear row 54 are removed, thereby removing the connections to the neutral terminal. In order to connect the end leads U6, V6 and W6 to the appropriate output terminal, collars 58 are first placed on the appropriate studs in the front row 52, and then long links 56 are used to connect the appropriate studs in the rear row to those in the front row. The collars 58 raise the level of the long links 56 so that they pass over the links in the middle row 53. In this embodiment, the W2 and W5 end leads are also connected to the neutral terminal using a short link.

Thus the embodiment illustrated in Figures 6 through 9 can allow users in the field to switch to different connections using links (and where appropriate collars) instead of moving leads. In this embodiment, the end leads from the stator windings do not need to be moved from the locations shown in Figure 6. The lengths of the links and the distances between the studs are chosen to minimise the risk of accidental misconnection. Furthermore, the lengths of the studs are chosen such that, in the case of a low boss 48, only the studs 44 with the longer of the two lengths can be connected to the studs which extend out of a high boss 49. This further minimises the risk of misconnection. The difference in height between the two different types of boss 48, 49 is chosen to ensure sufficient distance, and thus sufficient electrical separation, between different phases and/or neutral.

Figures 10 through 12 illustrate how the stator windings can be connected in various different connection arrangements in another embodiment of the invention. In this embodiment it is again assumed that the machine is a three-phase machine with two coils per phase, and two end leads from each coil. The end leads from the stator coils are labelled using the same labelling convention as in Figure 2.

Figure 10 shows how the stator windings can be connected in a series star arrangement. In this embodiment, the rear row 54 of studs is used to connect the end leads U5 to U2, V5 to V2 and W5 to W2. In the arrangement shown, this is achieved by connecting the end leads U5 and U2 to one stud in the rear row, the end leads V5 and V2 to another stud in the rear row, and the end leads W5 and W2 to a further stud in the rear row. The end leads U6, V6 and W6 are all connected directly to the neutral terminal. As in the previous embodiment, the end leads Ul, V1 and W1 are connected directly to the respective output terminal U, V, W. The output terminals are formed from L-shaped lugs 60.

Alternatively, it would be possible, for example, to connect the end leads U5 to U2 to adjacent studs in the middle row 53, and to connect the two studs using a short link 55. Similar arrangements could be used to connect the end leads V5 to V2, and W5 to W2. Furthermore, some or all of the end leads U6, V6 and W6 could be connected to the neutral studs in the rear row 54 (right hand side in Figure 10), and these studs could be connected to the neutral studs in the front row 52 using long links 56. Various other possible arrangements will be apparent to the skilled person.

Figure 11 shows how the stator windings can be connected in a parallel star arrangement in this embodiment. In order to move from the series star arrangement of Figure 10 to the parallel star arrangement of Figure 11, it is necessary to move the end leads U2, V2 and W2 to the neutral terminal, and the end leads U5, V5 and W5 to respective ones of the U, V and W terminals (see Figures 3). In this embodiment, the end leads U5, V5 and W5 are moved to respective studs in the middle row 53. The end leads U5, V5 and W5 are connected to the respective U, V and W terminals using short links 55 between the studs in the middle row 53 and the corresponding output terminal. The end leads U2, V2 and W2 are moved to the neutral terminal in the rear row 54. A long link 56 is used to connect the neutral terminal in the rear row to that in the front row. The output terminals are formed from L-shaped lugs 60 in the same way as in the previous embodiments.

Figure 12 shows how the stator windings can be connected in a series delta arrangement in this embodiment. In order to move from the series star arrangement of Figure 10 to the series delta arrangement of Figure 12, it is necessary to connect the end lead U6 to the V terminal, the end lead V6 to the W terminal, and the end lead W6 to the U terminal (see Figures 3). In this embodiment, this is achieved by moving the end leads U6, V6 and W6 to the appropriate output terminal. Although not shown in Figure 12, a link could also be provided from, for example, the W2 and W5 end leads to a neutral terminal.

The output terminals are formed from L-shaped lugs 60.

Figure 13 shows how the stator windings can be connected in a double delta arrangement in this embodiment. In such an arrangement, it is necessary to connect the end leads U1 and V6 to each other and to the U terminal; the end 35 leads V1 and W6 to each other and to the V terminal; the end leads W5 and U6 to each other and to the W terminal; the end leads W2 and V5 to each other; and the end leads U2, U5, V2 and W1 to each other and to the neutral (N) terminal. In the example shown in Figure 13, this is achieved in the following way. The end leads U1 and V6 are connected to the studs in the front row 52 which are used for the U terminal. The end leads V1 and W6 are connected to the studs in the front row 52 which are used for the V terminal. The end leads U6 are connected to the studs in the front row which are used for the W terminal, the end leads W5 are connected to an adjacent stud in the middle row 53, and a short link 55 is connected between this stud and the W terminal. The end leads W1 and U5 are connected to the studs in the front row 52 which are used for the N terminal, the ends leads U2 and V2 are connected to the studs in the rear row 54 which are used for the N terminal, and long links 56 are connected between the studs in the rear row and the studs in the front row.

Thus it will be appreciated that the disclosed terminal board can also be used to connect the stator windings in various different connection arrangements by moving the appropriate end leads as well as or instead of connecting links between the studs.

Figures 14 through 17 show a terminal board in another embodiment of the invention. Referring to Figure 14, the terminal board 70 comprises a base 72 and a plurality of studs. As in the previous embodiments, the studs extend out of bosses in the base. However, in this embodiment, bosses of three different heights and studs of three different lengths are provided. In Figure 14, the studs 74 have a first, shorter length; the studs 75 have a second intermediate length; and the studs 76 have a third, longer length. The bosses 77 have a first, lower, height; the bosses 78 have a second, intermediate height; and the bosses 79 have a third, higher height. This can help to achieve the required electrical separation between the various connectors. Other features of the terminal board 70 may be the same as or similar to the corresponding features of the terminal board 40 described above with reference to Figures 4 through 13.

Figure 14 shows the terminal board 70 connected in a series star connection arrangement. Figure 15 shows the terminal board 70 connected in a parallel star connection arrangement. Figure 16 shows the terminal board 70 connected in a series delta connection arrangement. Figure 17 shows the terminal board 70 connected in a double delta connection arrangement.

It will be appreciated that embodiments of the present invention have been described by way of example only, and variations in detail may be made within the scope of the appended claims. For example, while in one embodiment the terminal board has three rows of studs and 19 (or 21) studs in total, it will be appreciated that a different number of studs and/or rows could be used instead, depending for example on the number of coils and/or the type of connection arrangements with which the board is to be used. Furthermore, in some cases it may be possible to provide the studs either in pairs, or as individual studs. Various different configurations of bosses and studs may be used. The bosses may have various different heights and the studs may have various different lengths. The electrical machine may have a different number of phases, and a different number of coils may be provided for each phase. The stator windings may use various different winding configurations, such as concentrated, distributed, lapped, single layer, double layer windings, triple layer, or any other appropriate configuration. Other modifications in detail will be apparent to the skilled person.

Claims

CLAIMS1. A terminal board for an electrical generator, the terminal board comprising a base and a plurality of studs which extend out of the base, wherein the studs are arranged in a two-dimensional array.
2. A terminal board according to claim 1, wherein the studs are arranged to connect end leads from generator windings to generator output terminals and/or to each other.
3. A terminal board according to claim 2, wherein the generator is a three-phase machine, the generator windings comprise at least two coils per phase, and the end leads are end leads of the coils.
4. A terminal board according to claim 2 or 3, wherein the studs are arranged such that the generator windings can be configured in a plurality of different connection arrangements.
5. A terminal board according to claim 4, wherein the plurality of different connection arrangements comprise at least one of a star connection arrangement and a delta connection arrangement.
6. A terminal board according to any of claims 2 to 5, wherein the studs are arranged such that the windings can be configured in a plurality of different connection arrangements without moving the end leads.
7. A terminal board according to any of the preceding claims, wherein the total number of studs exceeds the number of studs which is required for a single connection arrangement.
8. A terminal board according to any of the preceding claims, wherein the studs are arranged in at least three rows.
9. A terminal board according to claim 8, wherein one row of studs is used for generator output terminals.
10. A terminal board according to any of the preceding claims, wherein the base has an upper surface, and the studs extend out of a plane of the upper surface.
11. A terminal board according to any of the preceding claims, wherein the terminal board is arranged to mount onto the generator such that the base extends in a first direction which is parallel to an axis of the generator, and a second direction which is tangential to a circumference of the generator.
12. A terminal board according to any of the preceding claims, wherein the terminal board is arranged such that it can receive end leads from generator windings on two different sides.
13. A terminal board according to any of the preceding claims, wherein the base comprises a plurality of bosses, and the studs extend out of the bosses.
14. A terminal board according to claim 13, wherein the terminal board comprises bosses of at least two different heights, and the bosses allow electrical connections to studs and/or between studs to be made at two different distances from a plane of an upper surface of the base.
15. A terminal board according to any of the preceding claims, wherein the terminal board comprises studs of at least two different lengths.
16. A terminal board according to claim 15, wherein the longer studs allow electrical connections to be made at two different distances from a plane of an upper surface of the base, and the shorter studs allow electrical connections to be made at only one of the two different distances.
17. A terminal board according to claim 16, wherein an electrical connection can be made to a longer stud at one of the two distances by placing a removable spacer on the stud.
18. A terminal board according to any of the preceding claims, wherein at least some of the studs are arranged in pairs, and a pair of studs is interconnectable by means of a rigid link.
19. A terminal board according to claim 18, wherein generator windings are configurable in a plurality of different connection arrangements by reconfiguring the links.
20. A terminal board according to claim 18 or 19, wherein the studs of at least one pair are separated from each other by a different distance than the studs of at least one other pair.
21. A terminal board according to any of claims 18 to 20, wherein the studs of at least one pair are connectable using a rigid link of a first length, and the studs of least one other pair are connectable using a rigid link of a second length different from the first.
22. A terminal board assembly comprising a terminal board according to any of the preceding claims and a plurality of rigid links for connecting studs on the terminal board.
23. A terminal board assembly according to claim 22, further comprising at least one removable spacer for spacing a connector on a stud.
24. A generator comprising a terminal board or terminal board assembly according to any of the preceding claims.
25. A method of reconfiguring windings of an electrical generator, wherein end leads of the windings are connected to a terminal board comprising a base and a plurality of studs which extend out of the base, the method comprising reconfiguring a connection arrangement of the windings by reconfiguring links between the studs and/or moving one or more of the end leads.