Electrical power distribution systems with a bypass unit that couples to a load and electrically engages one of two alternate units for powering the load and related methods

Patent metadata

Field	Value
Publication number	US-12074429-B2
Application number	US-202218050592-A
Country	US
Kind code	B2
Filing date	Oct 28, 2022
Priority date	Jun 28, 2019
Publication date	Aug 27, 2024
Grant date	Aug 27, 2024

Abstract

Electrical power distribution systems with a bypass unit that electrically engages one of two alternate units for powering a load while electrically isolating the other using a power transfer switch with first and second contactors and mechanical and electrical interlocks to allow a technician to access one of the alternate units when de-energized and in position while the other of the alternate units is energized and powering the load.

First claim

That which is claimed is:

1. An electrical power distribution system, the system comprising:
a bypass unit coupled to a load, the bypass unit comprising a power transfer switch;
a first unit comprising a first disconnect switch configured to selectively couple a power bus and the power transfer switch; and
a second unit comprising a second disconnect switch configured to selectively couple the power bus and the power transfer switch,
wherein the bypass unit is operable to selectively establish electrical connection to the load with a selected one of the first and second units at a time and isolate a remaining one of the first and second units from the electrical connection with the load, wherein the isolation is effectuated independently by the bypass unit.

2. The system of claim 1 , further comprising the power bus, wherein while the selected one of the first and second units is energized and powering the load, the other unit is electrically isolated from the load and accessible for maintenance.

3. The system of claim 1 , wherein, when the power transfer switch couples the first unit to the load, the first disconnect switch is closed while the second disconnect switch is open to electrically isolate the second unit electrically from the load and the first unit.

4. The system of claim 1 , wherein the first disconnect switch and the second disconnect switch each comprise a circuit breaker, and wherein the power transfer switch comprises auxiliary switches that are configured to automatically transmit a trip signal to the first unit prior to or concurrently with engaging the second unit.

5. The system of claim 1 , wherein the first and second units each further comprise a housing and a power disconnect assembly with extendable/retractable power stabs that independently move relative to the housing to connect to and disconnect from the power bus, and wherein the extendable/retractable power stabs of only one of the first unit or the second unit is permitted to be connected to the power bus at any one time.

6. The system of claim 1 , wherein the first unit comprises a first door and the second unit comprises a second door, wherein the system further comprises interlocks that prevent the first door from opening when either the first disconnect switch is closed or the first unit is coupled to the load and prevent the second door from opening when either the second disconnect switch is closed or the second unit is coupled to the load.

7. The system of claim 6 , wherein the first unit comprises a first motor starter and the second unit comprises a second motor starter, and wherein the electrical power distribution system further comprises at least one structure with defined spaced-apart internal compartments that hold the power transfer switch, the first unit, and the second unit in different ones of the defined spaced-apart internal compartments.

8. The system of claim 1 , wherein the bypass unit comprises a housing with a front wall, side walls, and a rear wall and is devoid of power stabs and does not directly connect to the power bus.

9. The system of claim 8 , wherein each of the bypass unit, the first unit, and the second unit includes a separate housing that is independently insertable and removable from a respective compartment in at least one structure of the system.

10. The system of claim 8 , wherein the first and second disconnect switches are circuit breakers, and wherein at least one of the bypass unit or the first and second units are electrically coupled to cause a first one of either the first disconnect switch or the second disconnect switch to trip to an open state when a second one of the first disconnect switch or the second disconnect switch is closed to allow conduction whereby only a single one of the first or second disconnect switch is closed at any one time.

11. The system of claim 1 , wherein the isolation is effectuated independently by the power transfer switch.

12. The system of claim 1 , wherein the bypass unit comprises a load-side circuit breaker, positioned proximate to the power transfer switch relative to the first and second units.

13. A bypass unit for an electrical power distribution system, comprising:
a power transfer switch coupled to a load,
wherein the bypass unit is operable to selectively establish electrical connection to the load with a selected one of a first unit or a second unit at a time and isolate the other unit from electrical connection with the load, wherein the first unit includes a first disconnect switch configured to selectively couple a power bus and the power transfer switch, and wherein the second unit includes a second disconnect switch configured to selectively couple the power bus and the power transfer switch, wherein the isolation is effectuated independently by the bypass unit.

14. The bypass unit of claim 13 , wherein, when the power transfer switch couples the first unit to the load, the first disconnect switch is closed while the second disconnect switch is open to electrically isolate the second unit electrically from the load and the first unit.

15. The bypass unit of claim 13 , wherein the first and second units each further comprise a housing and a power disconnect assembly with extendable/retractable power stabs that independently move relative to the housing to connect to and disconnect from the power bus, and wherein the extendable/retractable power stabs of only one of the first unit or the second unit is permitted to be connected to the power bus at any one time.

16. The bypass unit of claim 13 , wherein the first and second disconnect switches are circuit breakers, and wherein at least one of the bypass unit or the first and second units are electrically coupled to cause a first one of either the first disconnect switch or the second disconnect switch to trip to an open state when a second one of the first disconnect switch or the second disconnect switch is closed to allow conduction whereby only a single one of the first or second disconnect switch is closed at any one time.

17. The bypass unit of claim 13 , wherein the bypass unit comprises a load-side circuit breaker, positioned proximate to the power transfer switch relative to the first and second units.

18. A method of transferring power from one unit to another unit to power a load using a motor control center (MCC), comprising:
detecting an event associated with a first unit, the first unit coupling a power bus and a power transfer switch;
opening a first disconnect switch in the first unit to uncouple the power transfer switch from the power bus via the first unit;
opening a first contactor of the power transfer switch to electrically isolate the first unit from the load; and
closing a second contactor to power the load using a second unit, the second unit comprising a second disconnect switch that selectively couples the power bus and the power transfer switch.

19. The method of claim 18 , wherein the event includes at least one of a power failure or malfunction.

20. The method of claim 18 , wherein the power transfer switch is operable to selectively establish electrical connection to the load with a selected one of the first and second units at a time and isolate the other unit from the electrical connection with the load.

Assignees

• Eaton Intelligent Power Ltd

Inventors

• Morris Robert A
• Roush Jr Morris Len
• Hussey Matthew R

Classifications

• H02H7/0822

  Integrated protection, motor control centres · CPC title

• H02H3/023

  by short-circuiting · CPC title

• H02H7/0844 Primary

  Fail safe control, e.g. by comparing control signal and controlled current, isolating motor on commutation error · CPC title