Tap changer with an improved monitoring system

Patent metadata

Field	Value
Publication number	US-10840033-B2
Application number	US-201715611124-A
Country	US
Kind code	B2
Filing date	Jun 1, 2017
Priority date	Mar 27, 2011
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

An on-load tap changer is provided having a plurality of modules, each of which is operable to change taps in a transformer winding. The tap changer includes a motor connected to rotate at least one shaft. The at least one shaft is connected to the tap change modules and is operable upon rotation to cause the tap change modules to each perform a sequence of operations that effectuate a tap change. A multi-turn absolute encoder is connected to the at least one shaft. A monitoring system is connected to the encoder and is operable to determine from the position of the at least one shaft where the tap change modules are in the sequence of operations.

First claim

What is claimed is:

1. An on-load tap changer for making tap changes in a transformer winding, the tap changer comprising:
a tap change module configured to be connected to the transformer winding and comprising a bypass switch assembly, a vacuum interrupter assembly and a selector switch assembly;
a motor connected to rotate at least one shaft, wherein the at least one shaft is connected to the tap change module and is operable upon rotation to cause the tap change module to perform a sequence of operations that effectuate a tap change, the operations comprising actuating the bypass switch assembly, actuating the vacuum interrupter assembly and actuating the selector switch assembly;
a multi-turn absolute encoder connected to the at least one shaft and operable to determine a position of the at least one shaft; and
a monitoring system connected to the encoder to receive the position of the at least one shaft and operable to monitor a tap change by determining from the position of the at least one shaft where the tap change module is in the sequence of operations.

2. The on-load tap changer of claim 1 , wherein the at least one shaft comprises a motor shaft connected by a transmission shaft to the tap change module; and
wherein the encoder is connected to the motor shaft and is operable to determine the position of the motor shaft.

3. The on-load tap changer of claim 1 , wherein the at least one shaft comprises a motor shaft, a transmission shaft connected between the motor shaft and the tap change module, and a first side shaft connected by at least one gear to the transmission shaft so as to rotate therewith; and
wherein the multi-turn absolute encoder is connected to the first side shaft and is operable to determine the position of the first side shaft.

4. The on-load tap changer of claim 3 , wherein the position of the first side shaft comprises the number of rotations of the first side shaft and the angular position of the first side shaft from 0-360 degrees.

5. The on-load tap changer of claim 1 , wherein the selector switch assembly comprises a pair of movable contacts and a plurality of fixed contacts configured to be electrically connected to taps of the transformer winding, respectively;
wherein the movable contacts are movable among a plurality of different tap positions, wherein in each tap position, the movable contacts are both connected to the same fixed contact or are connected to adjacent fixed contacts, respectively; and
wherein the monitoring system is operable to determine the tap position of the movable contacts from the position of the at least one shaft.

6. The on-load tap changer of claim 1 , wherein the monitoring system is operable to control the motor to perform a tap change within a user-selectable predetermined period of time.

7. A method for making tap changes in a transformer winding, the method comprising:
operating a motor to rotate a shaft connected to a tap change module;
in response to rotation of the shaft, effectuating a sequence of tap change operations by a tap change module connected to the transformer winding, the tap change operations comprising:
actuating a bypass switch assembly of the tap change module;
actuating a vacuum interrupter assembly of the tap change module; and
actuating a selector switch assembly of the tap change module;

determining, by a multi-turn absolute encoder connected to the shaft, a position of the shaft;
receiving, by a monitoring system connected to the encoder, the position of the shaft; and
determining, by the monitoring system based on the position of the shaft, where the tap change module is in the sequence of tap change operations.

8. The method of claim 7 , wherein the shaft comprises a motor shaft connected by a transmission shaft to the tap change module; and
wherein determining the position of the shaft comprises determining, by the encoder, a position of the motor shaft.

9. The method of claim 7 , wherein the shaft comprises:
a motor shaft;
a transmission shaft connected between the motor shaft and the tap change module; and
a first side shaft connected by at least one gear to the transmission shaft so as to rotate therewith, wherein the multi-turn absolute encoder is connected to the first side shaft, and
wherein determining the position of the shaft comprises determining by the encoder, the position of the first side shaft.

10. The method of claim 9 , wherein determining the position of the first side shaft comprises:
determining a number of rotations of the first side shaft; and
determining an angular position of the first side shaft from 0-360 degrees.

11. The method of claim 7 , wherein the selector switch assembly comprises a pair of movable contacts and a plurality of fixed contacts electrically connected to taps of the transformer winding, respectively,
wherein the movable contacts are movable among a plurality of different tap positions, wherein in each tap position, the movable contacts are both connected to the same fixed contact or are connected to adjacent fixed contacts, respectively, the method further comprising:
determining, by the monitoring system based on the position of the shaft, the tap position of the movable contacts.

12. The method of claim 7 , further comprising:
selecting, by a user, a predetermined period of time; and
controlling, by the monitoring system, the motor to perform a tap change within the predetermined period of time.

13. The method of claim 7 , further comprising:
measuring a time required to perform at least one of the tap change operations;
determining, based on the time required, whether the at least one of the tap change operations was timely performed; and
determining that an error has occurred in response to determining that the at least one of the tap change operations was not timely performed.

14. The method of claim 7 , further comprising:
determining whether a current flowing through the vacuum interrupter assembly is properly present or absent after at least one of the tap change operations has been completed; and
determining that an error has occurred based on determining that the current is not properly present or absent after the at least one of the tap change operations has been completed.

15. The method of claim 7 , wherein the selector switch assembly comprises a pair of movable contacts and a plurality of fixed contacts electrically connected to taps of the transformer winding, respectively, and
wherein the movable contacts are movable from being connected to a beginning tap of the transformer winding to being connected to an ending tap of the transformer winding during a tap change, the method further comprising:
determining, by the monitoring system, that an error has occurred; and
controlling, by the monitoring system in response to the error, the motor to either continue the tap change and move the movable contacts to being connected to the ending tap, or to cancel the tap change and move the movable contacts back to being connected to the beginning tap, based on where the tap change module is in the sequence of tap change operations.

16. The method of claim 15 , further comprising controlling, by the monitoring system in response to the error, the motor to either continue the tap change or to cancel the tap change, thereby cutting off power to the motor.

17. The method of claim 15 , wherein the bypass switch assembly comprises a bypass switch,
wherein the vacuum interrupter assembly comprises a vacuum interrupter having a pair of contacts disposed in a vacuum bottle, and
wherei

Assignees

• Abb Power Grids Switzerland Ag

Inventors

• Teising William James
• Elick Robert Alan

Classifications

• H01H3/605

  making use of a fluid damper · CPC title

• H01H3/54

  Mechanisms for coupling or uncoupling operating parts, driving mechanisms, or contacts · CPC title

• H01H33/66

  Vacuum switches · CPC title

• H01H9/0033

  with means for indicating the selected tap or limiting the number of selectable taps · CPC title

• H01H2009/0061

  Monitoring tap change switching devices · CPC title