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-11545826-B2
Application number	US-202016911899-A
Country	US
Kind code	B2
Filing date	Jun 25, 2020
Priority date	Jun 28, 2019
Publication date	Jan 3, 2023
Grant date	Jan 3, 2023

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 comprising:
a power bus;
a bypass unit comprising a power transfer switch coupled to a load;
a first unit comprising a first disconnect switch configured to couple the power bus to the power transfer switch; and
a second unit comprising a second disconnect switch configured to couple the power bus to the power transfer switch,
wherein the power transfer switch comprises mechanically interlocked first and second contactors configured to selectively couple only one of the first and second units to the load at any one time,
wherein the bypass unit includes a circuit breaker configured to couple the first unit to the first contactor, wherein the circuit breaker has an operator mechanism configured to be moved between ON and OFF positions to close and open the circuit breaker, respectively, and configured to allow a user to lock the operator mechanism in the ON or OFF position,
wherein, when the first disconnect switch is closed and the power transfer switch couples the first unit to the load, the second disconnect switch is open to electrically isolate the second unit from the load and the first unit, and
wherein, when the first disconnect switch is closed and the power transfer switch couples the second unit to the load, the first disconnect switch is open to electrically isolate the first unit from the load and the second unit,
wherein, at any one point in time during normal operation, the power transfer switch of the bypass unit is configured to electrically connect the power bus to the load using only one of the first unit or the second unit,
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 from the load and the first unit, and
wherein, when the power transfer switch couples the second unit to the load, the second disconnect switch is closed while the first disconnect switch is open to electrically isolate the first unit electrically from the load and the second unit.

2. The electrical power distribution 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.

3. The electrical power distribution 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.

4. The electrical power distribution system of claim 1 , 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 electrical distribution system.

5. The electrical power distribution system of claim 1 , wherein the first unit further comprises a first motor starter and the second unit further 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 bypass unit, the first unit and the second unit in different ones of the defined spaced-apart internal compartments, wherein the first unit comprises a first front door with a first disconnect operator handle operably coupled to the first disconnect switch, wherein the second unit comprises a second front door with a second disconnect operator handle operably coupled to the second disconnect switch, and wherein the electrical power distribution system further comprises interlocks that (a) prevent the first door from opening when either the first disconnect switch is closed or the first unit is coupled to the load and (b) prevent the second door from opening when either the second disconnect switch is closed or the second unit is coupled to the load.

6. The electrical power distribution system of claim 1 , wherein the bypass unit and the first and second units are configured to be insertable and removable from spaced-apart compartments of a structure defining internal compartments, wherein the second electrical path in the bypass unit is devoid of a circuit breaker, and wherein the bypass unit further comprises a manually activatable back-up bypass path as a third path in the bypass unit comprising a circuit breaker that connects the load to the second unit without requiring the second path from the second contactor, optionally wherein the third path and the second path merge in the bypass unit to a common conductor output from the bypass unit, wherein the common conductor output is configured to couple to the second unit.

7. The electrical power distribution system of claim 1 , 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.

8. The electrical power distribution system of claim 1 , wherein the electrical distribution device is a motor control center (MCC).

9. The electrical power distribution 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 contactor.

10. The electrical power distribution system of claim 1 , further comprising a relay system associated with the first unit, wherein the relay system is configured to detect a malfunction or power off event of the first unit and responsively (i) trip open the circuit breaker and open the first contactor to decouple the first unit from the load and (ii) close the second contactor to couple the second unit to the load and automatically transfer power from the power bus to the second unit and the second electrical path and to the load and (ii) automatically directly or indirectly via an auxiliary switch transmit a control signal to the circuit breaker in the bypass unit to cause the circuit breaker to trip.

11. The electrical power distribution system of claim 1 , wherein the first unit and the second unit are provided as one of options A-L:

Option
first unit
second unit

A
VFD unit
VFD unit

B
Soft Starter
Soft Starter

(Reduced Voltage
(Reduced Voltage

starter) unit
starter) unit

Assignees

• Eaton Intelligent Power Ltd

Inventors

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

Classifications

• H02H3/023

  by short-circuiting · CPC title

• H02H7/0822

  Integrated protection, motor control centres · CPC title

• H02H7/0844 Primary

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