EP3022757B1 - On-load tap changer and a method for the emergency adjustment of a defined switching position of an on-load tap changer - Google Patents

Description

The present invention relates to an on-load tap-changer. In particular, the on-load tap-changer has an electric motor and a force accumulator, which are mechanically coupled via a transmission provided with a transmission housing. The transmission has a gear shaft on which a toothing is formed.

Furthermore, the invention relates to a method for emergency operation setting a defined switching position of an on-load tap-changer.

On-load tap-changers (abbreviated OLTC) are well known and commonly used in the art. They are used for uninterrupted switching between different winding taps of tapped transformers. On-load tap-changers are divided into load selectors and diverter switches with selectors.

In a diverter switch with selector, such as in the German patent DE 100 55 406 C1 discloses the selector, consisting of a fine selector and possibly a preselector, arranged below the diverter switch. The selector is used for powerless selection of the respective new winding tapping of the tapped transformer to be switched to. The diverter switch is used for subsequent rapid and uninterrupted switching from the wired to the new, preselected winding tap to be wired.

The Chinese utility model font CN 2870107 Y discloses a steering drive for an on-load tap changer comprising a transmission with a horizontal drive shaft. One end of the drive shaft can be coupled to a drive motor. The remaining gear surrounded by a gearbox. The horizontal drive shaft transmits its rotational movement via an angular gear consisting of a bevel pinion of the drive shaft and a bevel gear of the input shaft, transmits to the input shaft.

The Chinese patent application CN 102623210 A discloses a motor-driven transmission with a planetary gear and a position indicator for an on-load tap-changer.

The Chinese utility model font CN 202258744 U relates to a transmission and a transmission control for on-load tap-changer, in particular with an electrical system for emergency operation. In a transmission housing, a vertically mounted output shaft and a drive shaft are provided. The drive shaft is provided with a cross member and a thrust bearing. In addition, a worm wheel on the output shaft is connected via a worm shaft to the drive shaft. The electrical system and the transmission control allow switching between electrical and manual operation of the on-load tap-changer.

The Bulgarian patent BG 66062 B1 discloses a transmission for the electromotive actuation of an on-load tap-changer. The connection of the shaft of the electric motor and the drive shaft of the on-load tap-changer realized by an integrated planetary gear in the flange of the electric motor. Via a worm gear, a control shaft is mechanically coupled to the drive shaft. One end of the control shaft is guided out of a gear housing and carries a disc with one or more recesses, which cooperate with a control unit.
The German patent application DE 35 41 888 A1 discloses a transmission for stepwise actuating a diverter switch converter with a hand crank actuatable manual drive shaft. An output shaft can be coupled to one with the Umstellerwelle and performs one switching step per switching step. A housing includes a transmission gear coupling the manual drive shaft and output shaft and a switch position indicator with viewing window. Hand drive shaft and output shaft are arranged in parallel and are mechanically coupled by an orthogonally arranged gear shaft via a respective worm thread. By varying the pitch of these two threads, the gearbox can translate one revolution of the drive shaft into 8½ revolutions on the crankshaft that an operator must apply in manual mode. EP 2 535 911 A1 discloses an on-load tap changer according to the preamble of claim 1. An object of the invention is to provide a simple, low-cost and low-maintenance on-load tap-changer in which a defined shift position can be set in a safe, damage-free, ergonomic and easy-to-use manner in the manual emergency drive.
This object is achieved by an on-load tap changer according to claim 1.
Another object of the invention is to provide a method by which a defined shift position of an on-load tap-changer can be set in a safe, damage-free, ergonomic and easy-to-use manner in the manual emergency drive.

This object is achieved by a method according to claim 9. The on-load tap-changer according to the invention comprises a drive, preferably an electric motor, for mounting an energy accumulator which effects the actual switching of the on-load tap-changer. Electric motor and energy storage are mechanically coupled via a gearbox. The transmission is provided with a transmission housing and has a transmission shaft on which a toothing, such as a screw thread, is formed. On the transmission shaft, an extension is formed, which has a free end for attaching a tool for mounting the force accumulator. In particular, the free end can be designed as an adapter for the form-fitting attachment of a tool. The adapter may for example be a hexagon head, which can be operated with a corresponding tool. Adapter and tool cooperate according to the key lock principle, so that the gear shaft can be operated accordingly.

In one embodiment of the on-load tap-changer according to the invention, the free end of the extension of the gear shaft can protrude from an opening in the gear housing, so as to set the tool at the free end. In an alternative embodiment, the free end of the extension of the transmission shaft may be accessible via the opening of the transmission housing. In this case, the tool protrudes into the gear housing to operate the gear shaft emergency operation.

The opening in the driveline housing can be provided with a protective cap which is detachably mounted on the transmission housing and in particular positively covers the free end of the extension of the transmission shaft and also the opening of the transmission housing. Preferably, the protective cap is provided with a sealing element to prevent dirt or moisture entry into the transmission.

In particular, the protective cap can be configured and arranged such that it, mounted on the transmission housing, actuates a circuit breaker arranged in the transmission housing. The circuit breaker can, for example, enable the circuit of the electric motor as soon as it is actuated. Consequently, the circuit of the electric motor is disconnected when the protective cap is removed for safety reasons. For an operator of the tool attached to the free end of the gear shaft, it is ensured that the gear is not damaged by an erroneous drive of the electric motor or the operator himself is injured. To interrupt the circuit of the electric motor, a projection on the protective cap is formed. When mounted on the transmission housing cap the projection protrudes through the opening into the transmission housing and actuates the circuit breaker, so that the circuit of the electric motor is closed.

In a specific embodiment, the electric motor may be mechanically coupled to the transmission shaft via a first speed translator and the transmission shaft to a drive shaft of the energy accumulator via a second speed multiplier. A speed converter according to the invention is, for example, a preferably slip-free, gearless transmission with a 1: 1 different speed ratio between input speed and output speed. The first speed translator may be constructed of a pinion and a gear mechanically coupled thereto. The pinion with the electric motor and the gear with the gear shaft are each rigidly connected. The second speed multiplier can be constructed from the toothing of the transmission designed as a worm thread and a worm gear mechanically coupled thereto. The helical gear is rigidly connected to the input shaft.

The invention further relates to a method for emergency operation setting a defined switching position of an on-load tap-changer. In a first method step, a protective cap mounted on a transmission housing is removed. In the assembled state, the protective cap covers a free end of an extension of a transmission shaft of a transmission. The transmission mechanically couples an electric motor with a force accumulator for actuating a preselector and / or a Switching column of the on-load tap-changer. In a subsequent process step, a tool is attached to the free end of the extension of the transmission shaft. In the subsequent process step, the gear shaft is rotated by turning the tool by an operator until the energy storage is fully wound up. As soon as the energy accumulator is fully wound up, it is released by a mechanical device and its relaxation movement is converted into a defined rotational movement of a switching column and / or for actuating a preselector of the on-load tap-changer.

An advantage of the invention is the simple, safe, robust and cost-effective design of a transmission for an on-load tap-changer. For the manual emergency drive of the on-load tap-changer or to achieve a defined switching position of the on-load tap-changer, the transmission shaft has the extension, the free end can be used as an approach for the manual emergency drive of the on-load tap-changer.

In particular, it is advantageous that in the on-load tap-changer according to the invention the electric motor does not have to be dismantled in emergency operation, but only a protective cap has to be removed. In emergency operation, the operator and the on-load tap-changer are additionally protected, since the protective cap triggers a circuit breaker only in the state mounted on the gearbox housing, which releases the circuit of the electric motor. In emergency operation, the electric motor is de-energized.

Depending on the configuration of the first and second speed converter, the number of rotations that the electric motor or an operator must perform with the at the free end of the extension of the transmission shaft with the attached tool to raise the power storage, can be set independently. This has the advantage that the manual emergency operation with the tool and at the same time the electric motor operation can be designed for ergonomic values of revolutions per clamping operation of the energy accumulator or of torques. For example, the energy accumulator can be fully wound by a rotation of the input shaft with a torque of typically 150 Nm. By a suitably selected gear ratio of the second speed translator, an operator, for example, must apply only 10 Nm of torque to completely raise the power storage with 25.5 turns. At the same time, by suitably selecting the gear ratio of the first speed translator, the electric motor can be operated at much higher and more power efficient speed and torque ranges, e.g. with 128 revolutions per circuit or a torque of only 2.3 Nm.

Fig. 1

eine Perspektivansicht eines erfindungsgemäßen Laststufenschalters in Form eines dreiphasigen Lastwählers;

Fig. 2

eine Schnittansicht des Lastwählers entlang der in Fig. 1 eingezeichneten Schnittlinie A-A;

Fig. 3

eine Perspektivansicht des Schaltrohres des dreiphasigen Lastwählers nach Fig. 1, wobei drei am Schaltrohr befestigten Schaltsegmente und das massereiche Element zu sehen sind;

Fig. 4

eine weitere Perspektivansicht des Schaltrohres des dreiphasigen Lastwählers nach Fig. 1, wobei drei am Schaltrohr befestigten Widerstandsanordnungen und das massereiche Element zu sehen sind;

Fig. 5

zeigt eine Perspektivansicht auf das erfindungsgemäße Getriebe; und

Fig. 6

eine perspektivische Teilansicht des Getriebegehäuses nach Fig. 5 mit einer Öffnung im Getriebegehäuse und einer Schutzkappe zum Verschließen derselben.

In the following, the invention and its advantages will be described in more detail with reference to the accompanying drawings. Show it:

Fig. 1

a perspective view of an on-load tap changer according to the invention in the form of a three-phase load selector;

Fig. 2

a sectional view of the load selector along in Fig. 1 drawn section line AA;

Fig. 3

a perspective view of the switching tube of the three-phase load selector after Fig. 1 , wherein three switch segments attached to the switching tube and the massive element can be seen;

Fig. 4

another perspective view of the switching tube of the three-phase load selector after Fig. 1 showing three resistor arrangements fixed to the switching tube and the high-mass element;

Fig. 5

shows a perspective view of the transmission according to the invention; and

Fig. 6

a partial perspective view of the transmission housing after Fig. 5 with an opening in the gear housing and a protective cap for closing the same.

For identical or equivalent elements of the invention, identical reference numerals are used. For clarity, only reference numerals are shown, which are required for the description of the respective figure. The exemplified embodiments of the on-load tap-changer according to the invention and of the transmission according to the invention for a force accumulator of an on-load tap-changer do not constitute a restriction of the protective range defined by the patent claims for the invention.

Fig. 1 shows a perspective view of an on-load tap changer according to the invention in the form of a three-phase load selector 1. The load selector 1 has an electric motor 3 with a gear 5, which raises a force accumulator 13. If the energy storage device 13 is fully wound, ie tensioned, it is unlatched, releases its energy abruptly and actuates a switching tube 15. The rotating switching tube 15 is rotatably supported in the oil vessel 18. The oil vessel 18 is closed at the top with a lid 19 and also carries a bottom element 21st

The load selector 1 according to the invention has three phases L1, L2, L3, which are arranged one above the other in the oil vessel 18. About the three phases L1, L2, L3 sits a preselector 37. Electrical connection elements 39 for Ableitkontakte or stage contacts of the preselector 37 and the three phases L1, L2, L3 are arranged on the load selector 1, that they through a wall 17 of the oil vessel 18th to grab.

Fig. 2 shows a sectional view along the line AA of the load selector 1 from Fig. 1 , wherein a plan view of the phase L2 is shown. On an inner wall 20 of the oil vessel 18 for the phase L2 a plurality of plate-shaped and adapted to the contour of the inner wall 20 of the oil vessel 18 plate-shaped elements 411, which constitute an actuating element 41, respectively. Electrical connection elements 39 for the Ableitkontakte or stage contacts access by the corresponding Protective caps 30 on the outer wall 16 of the oil vessel 18 hold the arranged on the inner wall 20 of the oil vessel 18 plate-shaped elements 411. For this purpose, the electrical connection elements 39 via protective caps 30 with the Ableitkontakten not shown or the step contacts not shown together, so that the plate-shaped elements 411 are supported on the inner wall 20 of the oil vessel 18. The protective caps 30 rest on the outer wall 16 of the oil vessel 18. Each of the plate-shaped elements 411 has at least two control cams 31 which cooperate with corresponding and provided with rollers 43 operating levers 45 of the switching segment 25 of the corresponding phase L1, L2, L3.
The switching tube 15 carries in each phase L1, L2, L3 a holder 50 to which the high-mass element 36, the resistor assembly 27 and the switching segment 25 are mounted. The switching segment 25 is mounted in such a way that the rollers 43 of the actuating lever 45 cooperate with the corresponding control cams 31 of the plate-shaped elements 411.
3 and 4 show different perspective views of the switching tube 15 of the three-phase load selector 1 after Fig. 1 , with three attached to the switching tube 15 switching segments 25, so that the load selector 1 (see FIG. 2 ) comprises the three phases L1, L2, L3. In addition to the switching segments 25 on the rotating switching tube 15, resistor arrangements 27 are also attached, which are assigned to the individual phases L1, L2, L3 of the load selector 1. By turning the switching tube 15 contacts for step contacts 29S and contacts for Ableitkontakte 29A can be connected directly, the contacts for stage contacts 29S and the contacts for Ableitkontakte 29A cooperate with corresponding and not shown Ableitkontakten or the tap contacts, also not shown. A predetermined switching sequence is by means of the control cams 31 (see Fig. 2 ), so that a plurality of vacuum interrupters (not shown) in the individual switching segments 25 are opened or closed. In the embodiment of 3 and 4 carries the switching tube 15 a flywheel 35, wherein also on the switching tube a massive element 36 is mounted. The massive element 36 can also sit on the flywheel. The massive element 36 and the flywheel 35 serve to support the rotational movement of the switching tube 15 in order to ensure a defined switching from one switching position to the next.
Fig. 5 shows a perspective view of the transmission according to the invention 5, wherein parts of a transmission housing 90 are removed, in order to gain a better insight into the structure of the transmission 5. An electric motor 3 is releasably attached to the transmission housing 90. An unillustrated motor shaft of the electric motor 3 is connected to a pinion 53 of the transmission 5. The pinion 53 engages in a gear 54 which is rigidly connected to a gear shaft 61. The pinion 53 and the gear 54 form a first speed multiplier 51 which transmits the rotational motion of the motor shaft to the transmission shaft 61 at a first gear ratio. The transmission shaft 61 is mounted between two bearings 67 in the transmission housing. Between the two camps 67 carries the Transmission shaft 61 designed as a worm thread teeth 55. This worm thread engages in a helical gear 56 which is rigidly connected to a drive shaft 9 for mounting an energy accumulator 13. Together, the worm thread and the helical gear 56 form a second speed translator 52 which transmits the rotational movement of the gear shaft 61 to the input shaft 9 at a second gear ratio. Since the first speed translator 51 and the second speed translator 52 are arranged in series, the effective transmission ratio of the motor shaft to the input shaft 9 is obtained by multiplying the first and second transmission ratios.

On the side facing away from the electric motor 3, an extension 62 is formed with a free end 65 on the gear shaft 61. The free end 65 carries in the present embodiment designed as a hexagon head, screw head, ring, etc. adapter 63 to which a commercial tool 95 can be applied. The extension 62 of the transmission shaft 61 protrudes through an opening 93 so that it is not in contact with the transmission housing 90 and its free end 65 is outside the transmission housing 90. This facilitates the attachment of the tool 95 and the rotation of the tool 95th

The protective cap 91 covers the opening 93 of the gear housing 90 and the free end 65 of the extension 62 of the gear 61 when mounted with three fasteners 92 on the gear housing. In this case, a projection 97, which is formed on the protective cap 91, projects through the opening 93 into the transmission housing 90. The projection 97 may be formed as a tube. In the assembled state of the protective cap 91, the projection 97 actuates a circuit breaker 70, which is arranged in a closed circuit breaker chamber 73 of the gear housing 90. Via a flange 94, the gear housing 90 can be attached to a cover 19 of the on-load tap-changer 1 or to an intermediate housing 94.

Fig. 6 shows a partial perspective view of the transmission housing 90 after Fig. 5 with the opening 93 formed in the gear housing 90 and the protective cap 91 for closing the same. On the gear housing 90, an assembly aid 99 is formed, with which a recess 98 formed on one side on the protective cap corresponds. By this arrangement, the orientation in which the protective cap 91 can be mounted on the gear housing 90, clearly defined. In the outwardly closed circuit breaker chamber 73 of the gear housing 90, two terminals 74 are formed, through which the circuit breaker 70 is connected to the electrical lines of the circuit 71 of the electric motor 3. The circuit breaker 70 interrupts the circuit 71 as soon as the projection 97 of the protective cap 91 no longer acts on it.

LIST OF REFERENCE NUMBERS

1

On-load tap-changer, load selector

3

Drive, electric motor

5

transmission

13

power storage

15

switching tube

16

Outer wall of the oil vessel

17

wall

18

oil vessel

19

cover

20

inner wall

21

floor element

25

switching segment

27

resistor arrangement

29A

Contact for discharge contact

29S

Contact step contact

30

protective cap

31

cam

35

Inertia

351

first partial flywheel

352

second partial flywheel

36

massive element

37

selection

39

electrical connection element for discharge contact or step contact

41

actuator

43

role

411

plate-shaped element

45

actuating lever

51

first speed translator

52

second speed translator

53

pinion

54

gear

55

screw gear

56

Worm

61

threaded shaft

62

free end

63

adapter

70

breaker

71

circuit

73

Breaker chamber

74

connections

75

electric lines

81

motor shaft

90

gearbox

91

protective cap

92

fastener

93

opening

94

flange

95

Tool

96

against adapter

97

head Start

98

recess

99

mounting aid

P1, P2, P3

phase

Claims (9)

1. On-load tap changer (1) with an electric motor (3), which is mechanically coupled with a force storage unit (13) of the on-load tap changer (1) by way of a transmission (5) provided with a transmission housing (90), wherein the transmission (5) comprises a transmission shaft (61) formed with a toothing (55),
   characterised in that
   the transmission shaft (61) has an extension (62) having a free end (65) for attachment of a tool (95) for drawing up a force storage unit (13).
2. On-load tap changer (1) according to claim 1, wherein the free end (65) of the extension (62) protrudes from an opening (93) of the transmission housing (90) or is accessible by way of the opening (93) of the transmission housing (90).
3. On-load tap changer (1) according to claim 1 or 2, wherein a protective cap (91) over the free end (62) of the extension (62) of the transmission shaft (51) is detachably mounted on the transmission housing (90).
4. On-load tap changer (1) according to claim 3, wherein a circuitbreaker (70) arranged in the transmission housing (90) is actuable by way of the protective cap (91) mounted on the transmission housing (90).
5. On-load tap changer (1) according to claim 4, wherein a projection (97) is formed at the protective cap (91) and, when the protective cap (91) is mounted on the transmission housing (91), so protrudes into the transmission housing (90) that the circuitbreaker (70) is actuable.
6. On-load tap changer (1) according to any one of the preceding claims, wherein the electric motor (3) is mechanically coupled with the transmission shaft (61) by way of first rotational speed translation means (51) and the transmission shaft (61) is mechanically coupled with a drive input shaft (9) of the force storage unit (13) by way of second rotational speed translation means (52).
7. On-load tap changer (1) according to claim 6, wherein the first rotational speed translation means (51) is constructed from a pinion (53) and a gearwheel (54) mechanically coupled therewith, wherein the pinion (53) is fixedly connected with the electric motor (3) and the gearwheel (54) is fixedly connected with the transmission shaft (61).
8. On-load tap changer (1) according to claim 6 or 7, wherein the second rotational speed translation means (52) is constructed from the toothing (55), which is formed as a worm thread, of the transmission (5) and a helical gear (56) mechanically coupled therewith, wherein the helical gear (56) is fixedly connected with the drive input shaft (9).
9. Method for emergency-operation setting of a defined switching position of an on-load tap changer (1), characterised by the following steps:

   removing a protective cap (91), which is mounted on a transmission housing (90), of a transmission (5) for a force storage unit (13), whereby a free end (65) of an extension (62) of a transmission shaft (61) is accessible;

   attaching a tool (95) to the free end (65) of the extension (62) of the transmission shaft (61); and

   turning the tool (95) until the force storage unit (13) is fully drawn up.

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