High-voltage switches with arc preventing or extinguishing devic – Arc preventing or extinguishing devices – Polyphase
Reexamination Certificate
1999-05-17
2001-03-06
Scott, J. R. (Department: 2832)
High-voltage switches with arc preventing or extinguishing devic
Arc preventing or extinguishing devices
Polyphase
C218S120000, C218S154000
Reexamination Certificate
active
06198062
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a modular, high-voltage, vacuum-type recloser assembly operable in a three phase or a single phase mode and, more particularly, to a high-voltage, vacuum-type recloser utilizing modular construction of each of three independent recloser units thereby providing interchangability of the recloser units and facilitating adaption of the recloser assembly to operate as a single three phase recloser or as three independent one phase recloser units.
BACKGROUND OF THE INVENTION
High-voltage, three phase recloser assemblies (also referred to as reclosing relays) are used in three phase electric power distribution networks to provide for circuit breaking of electrical power when an overcurrent condition is sensed on any one of the three power transmission lines coupled to the recloser assembly. Typical voltage rating of such recloser assemblies range from 15 kilovolts (kV) to 38 kV and an interrupting current rating of up to 12,600 amps. A controller is electrically coupled to three solenoid actuated switching assemblies of the recloser assembly. When an overcurrent condition on a transmission line is sensed by a controller electrically coupled to the recloser assembly, controller causes the recloser assembly to open the three switching assemblies, each switching assembly being coupled to a different one of the three power lines. Each of the three switching assemblies includes a line terminal and a switch terminal coupled in series with a power transmission line. Tripping or opening a recloser switching assembly causes an open circuit condition between the line and switch terminals and interrupts the supply of power on that power transmission line. After a predetermined time, the controller sends electrical signals to the recloser switching assembly causing the solenoid switch to close and resuming power transmission through the switching assembly. The controller continually monitors for overcurrent conditions on the power transmission lines.
A prior art three phase recloser assembly is shown in
FIGS. 1 and 2
at
50
. As can be seen in
FIG. 2
, the recloser assembly
50
is typically mounted on a utility pole
85
. A controller monitors currents through the recloser assembly terminals and opens the three recloser switching assemblies when an overcurrent condition is sensed on one or more of the power transmission lines. Typically, current through the terminals is sensed via three current transformers (CTs), one CT positioned coaxial to each of the three line terminals
52
,
60
,
68
. The controller
90
is typically mounted on the pole
85
at a lower height above ground so as to be accessible to a technician standing on the ground. The controller
90
and recloser assembly
50
are electrically coupled by a cable
92
.
FIG. 1
shows a prior art vacuum type recloser assembly
50
manufactured by Joslyn Hi-Voltage Corporation, Cleveland Ohio 44105, the assignee of the present invention.
The recloser assembly
50
includes a tank
80
, at ground potential, and three sets of terminals
52
,
56
,
60
,
64
,
68
,
72
. The first set of terminals
52
(line terminal),
56
(switch terminal) provide for a circuit breaker connection for a first power distribution line (first phase of a three phase distribution network). The second set of terminals
60
,
64
provide for a circuit breaker connection for a second power line (second phase of the three phase network) and a the third set of terminals
68
,
72
provide for a circuit breaker connection for a third power line (third phase of the three phase network). Air bushings
54
,
58
,
62
,
66
,
70
,
74
insulate respective terminals
52
,
56
,
60
,
64
,
68
,
72
from the tank
80
. The tank
80
is filled with an dielectric insulating gas such as sulfur hexafluoride, SF
6
, or oil and is held at ground potential.
Three vacuum interrupter switch contact assemblies provide the circuit beaker connection between the first set of terminals, the second set of terminals and the third set of terminals. A suitable vacuum interrupter assembly is disclosed in U.S. Pat. No. 5,387,771 to Luehring issued Feb. 7, 1995, entitled “Axial Magnetic Field High Voltage Vacuum Interrupter” and assigned to the assignee of the present invention. U.S. Pat. No. 5,387,771 is incorporated herein in its entirety by reference.
Prior art three phase recloser assemblies were characterized by long assembly times and numerous switching components. Also, use of sulfur hexafluoride, SF
6
as an insulating material in the tank was less than desirable because of environmental concerns. Additionally, the recloser assembly could not easily be changed to accommodate single phase operation.
What is needed is an improved three phase recloser assembly that is more efficient to assemble than current art reclosers and has less switching components. What is also needed is a recloser that uses a more environmentally friendly insulating material. What is also needed is a recloser that can easily be adapted for three phase or single phase operation.
SUMMARY OF THE INVENTION
The present invention concerns a high voltage, modular recloser assembly which is operable in either a three phase mode or a one phase mode. The recloser assembly includes three modular recloser units each supporting a solenoid switching assembly electrically coupled between a line terminal and a switch terminal. A moveable switch contact, electrically coupled to the line terminal, and a stationary contact, electrically coupled to the switch terminal are disposed in an evacuated casing. Each of the switching assemblies is actuated by a solenoid switch. In the three phase mode of operation, the switching assemblies of each recloser are mechanically coupled or ganged so that the switching assembly are required to move in unison. For example, if an overcurrent condition is sensed on any one of three power transmission lines, all three solenoid switches will be tripped or opened thereby interrupting power on all three power transmission lines. Since the switching assemblies always must move in unison because of the mechanical coupling of the switches, a situation is prevented wherein one switch is in one position (open or closed) and the other two switches are in a different position. A situation in which one of the switching assemblies is in a different position that the other two switching position is undesirable. For example, if one switch were to be in the closed position and the other two switches were in the open position, one phase power would be transmitted along the transmission lines to a customer's power equipment requiring three phase power. Such a situation would likely cause damage to customer's equipment.
To permit one phase operation of the recloser assembly, the mechanical coupling of the switching assemblies is removed and the units operate independently (under the control of appropriate controllers) for single phase power control. Furthermore, the recloser assembly is comprised of three mechanically coupled recloser units. Each of the recloser units can be separated, if desired, and used as a stand-alone vacuum recloser device (operating under the control of an appropriate controller). For example a single unit could be mounted on a utility pole (stand alone configuration). Alternately, the recloser assembly could be mounted on a utility pole in a unitary configuration (all three recloser units mechanically coupled) or in a spread configuration wherein the three recloser units are mechanically separated, and mounted, for example, at 90 degree angles or 120 degree angles with respect to each other. As is evident, the versatility of the recloser assembly of the present invention in both operating modes (three phase and one phase) and in mounting configurations (unitary, spread and stand alone mounting) represent significant advantages over prior reclosers.
Each recloser unit includes a cast aluminum, generally cubic-shaped base defining an interior region in which a solenoid switch of the switching assembly is disposed.
Mather Brian D.
Steele Edward A.
Joslyn Hi-Voltage Corporation
Scott J. R.
Watts, Hoffmann, Fisher & Heinke Co. L.P.A.
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