Methods and systems for using a tapped transformer to generate voltage sags

Patent metadata

Field	Value
Publication number	US-10345831-B2
Application number	US-201615282265-A
Country	US
Kind code	B2
Filing date	Sep 30, 2016
Priority date	Sep 30, 2016
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A device includes a three phase supply input including a first phase input, a second phase input, and a third phase input. The device further includes a three phase supply output including a first phase output, a second phase output, and a third phase output. The device further includes a three-phase wye-connected auto-transformer having windings including a first winding, a second winding, and a third winding. At least one of the windings is rated for at least a maximum line to line voltage of the three phase supply input. The other two windings are rated for at least a maximum line to neutral voltage of the three phase supply input. One or more of the windings of the three-phase wye-connected auto-transformer are configured to be tapped to generate a voltage sag output as the three phase supply output.

First claim

What is claimed is:

1. A device comprising:
a three phase supply input comprising a first phase input, a second phase input, and a third phase input;
a three phase supply output comprising a first phase output, a second phase output, and a third phase output; and
a three-phase wye-connected auto-transformer having windings comprising a first winding, a second winding, and a third winding, wherein:
at least one of the windings is rated for at least a maximum line to line voltage of the three phase supply input,
the other two windings are rated for at least a maximum line to neutral voltage of the three phase supply input, and
one or more of the windings of the three-phase wye-connected auto-transformer are configured to be tapped to generate a voltage sag output as the three phase supply output.

2. The device of claim 1 , wherein:
the first phase input is connected to the first phase output,
the second phase input is connected to the second phase output,
the third phase input is connected to a first tap of the third winding,
a neutral line of the three phase supply input is connected to a neutral connection of the three-phase wye-connected auto-transformer, and
the third phase output is connected to a second tap of the third winding between the neutral connection and the first tap of the third winding.

3. The device of claim 1 , wherein:
the first winding is rated for at least the maximum line to line voltage of the three phase supply input,
the first phase input is connected to the first phase output,
the second phase input is connected to the second phase output and a first end of the first winding,
the third phase input is connected to a second end of the first winding, and
the third phase output is connected to a first tap of the first winding.

4. The device of claim 1 , wherein:
the first winding is rated for at least the maximum line to line voltage of the three phase supply input,
the first phase input is connected to the first phase output,
the second phase input is connected to a first end of the first winding,
the third phase input is connected to a second end of the first winding,
the second phase output is connected to a first tap of the first winding, and
the third phase output is connected to a second tap of the first winding, wherein the first tap and the second tap are located at approximately equal distances from a midpoint of the first winding.

5. The device of claim 1 , wherein:
the first phase input is connected to the first phase output,
the second phase input is connected to a first tap of the second winding,
the third phase input is connected to a first tap of the third winding,
a neutral line of the three phase supply input is connected to a neutral connection of the three-phase wye-connected auto-transformer,
the second phase output is connected to a second tap of the second winding between the first tap of the second winding and the neutral connection, and
the third phase output is connected to a second tap of the third winding between the first tap of the third winding and the neutral connection.

6. The device of claim 1 , further comprising a plurality of switches configured to switch the three phase output between a normal condition and a sag condition, wherein the voltage sag is generated during the sag condition.

7. The device of claim 1 , wherein the first winding is a center-leg of the three-phase wye-connected auto-transformer.

8. The device of claim 1 , wherein:
the first phase input is connected to a first tap of the first winding,
the second phase input is connected to a first tap of the second winding,
the third phase input is connected to a first tap of the third winding,
a neutral line of the three phase supply input is connected to a neutral connection of the three-phase wye-connected auto-transformer,
the first phase output is connected to a second tap of the first winding between the first tap of the first winding and the neutral connection,
the second phase output is connected to a second tap of the second winding between the first tap of the second winding and the neutral connection, and
the third phase output is connected to a second tap of the third winding between the first tap of the third winding and the neutral connection.

9. A method comprising:
receiving a three phase supply input comprising a first phase input, a second phase input, and a third phase input;
generating, with a three-phase wye-connected auto-transformer, a voltage sag at a three phase supply output comprising a first phase output, a second phase output, and a third phase output, the three-phase wye-connected auto-transformer having windings comprising a first winding, a second winding, and a third winding, wherein:
at least one of the windings is rated for at least a maximum line to line voltage of the three phase supply input,
the other two windings are rated for at least a maximum line to neutral voltage of the three phase supply input, and
one or more of the windings of the three-phase wye-connected auto-transformer are tapped to generate the voltage sag.

10. The method of claim 9 , wherein generating the voltage sag comprises generating a Type A sag such that:
the first phase input is connected to the first phase output,
the second phase input is connected to the second phase output,
the third phase input is connected to a first tap of the third winding,
a neutral line of the three phase supply input is connected to a neutral connection of the three-phase wye-connected auto-transformer, and
the third phase output is connected to a second tap of the third winding between the neutral connection and the first tap of the third winding.

11. The method of claim 9 , wherein generating the voltage sag comprises generating a Type B sag such that:
the first winding is rated for at least the maximum line to line voltage of the three phase supply input,
the first phase input is connected to the first phase output,
the second phase input is connected to a first end of the first winding and the second phase output,
the third phase input is connected to a second end of the first winding, and
the third phase output is connected to a first tap of the first winding.

12. The method of claim 9 , wherein generating the voltage sag comprises generating a Type C sag such that:
the first winding is rated for at least the maximum line to line voltage of the three phase supply input,
the first phase input is connected to the first phase output,
the second phase input is connected to a first end of the first winding,
the third phase input is connected to a second end of the first winding
the second phase output is connected to a first tap of the first winding, and
the third phase output is connected to a second tap of the first winding, wherein the first tap and the second tap are located at approximately equal distances from a midpoint of the first winding.

13. The method of claim 9 , wherein generating the voltage sag comprises generating a Type D sag such that:
the first phase input is connected to the first phase output,
the second phase input is connected to a first tap of the second winding,
the third phase input is connected to a first tap of the third winding,
a neutral line of the three phase supply input is connected to a neutral connection of the three-phase wye-connected auto-transformer,
the second phase output is connected to a second tap of the second winding between the first tap of the second winding and the neutral connection, and
the third phase output is connected to a second tap of the third winding between the first tap of the third winding

Assignees

• Rockwell Automation Tech Inc

Inventors

• Schneider Robert S

Classifications

• G01R31/2837

  Characterising or performance testing, e.g. of frequency response (transient response G01R27/28) · CPC title

• G01R31/2841

  Signal generators · CPC title

• G05F1/16

  combined with discharge tubes or semiconductor devices · CPC title

• G05F1/14 Primary

  using tap transformers or tap changing inductors as final control devices · CPC title