Electricity: circuit makers and breakers – Switch activation inhibitor – Actuator locking device
Reexamination Certificate
1999-12-17
2001-12-11
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Switch activation inhibitor
Actuator locking device
C200S050320
Reexamination Certificate
active
06329615
ABSTRACT:
The invention relates to generator circuits in electricity-producing stations, such as gas turbine installations, for example.
BACKGROUND OF THE INVENTION
Between the generator and the grid transformer which are interconnected by a set of busbars, such circuits include a generator circuit-breaker and switching apparatuses having two or three switching positions, which apparatuses are of the busbar switch and/or of the grounding switch type. Such a generator circuit can also be connected to a starter device via switch apparatus of this type.
Those various switch apparatuses are generally designed to be actuated automatically and electrically under the control of a control center. They must also be designed so as to be capable of being actuated manually by means of a handle in the event of an electricity failure, particularly a failure in the automatic control center. However, to ensure circuit element integrity, it is essential for manual actuation thereof to proceed in application of an accurately-specified procedure.
FIG. 6
is highly diagrammatic and shows an example of a generator circuit comprising a generator circuit-breaker FKG in series with a busbar switch SKG having two switching positions and connected between a generator
1
and a grid transformer
2
, together with two grounding switches MALT
1
and MALT
2
, each of which has two switching positions.
In
FIG. 6
, the generator circuit-breaker FKG and the busbar switch SKG are closed while the grounding switches MALT
1
and MALT
2
are open. The interlocking rules applicable to these various elements are common both to automatic actuation mode and to manual actuation mode and are as follows.
The busbar switch SKG must not be opened while the generator circuit-breaker FKG is closed. Neither of the grounding switches MALT
1
and MALT
2
must be closed while the busbar switch SKG is closed. The busbar switch SKG must not be closed while either of the grounding switches MALT
1
and MALT
2
is closed. The order of operations when actuating the busbar switch SKG and the grounding switches MALT
1
and MALT
2
starting from the configuration shown in
FIG. 6
is as follows. Firstly the generator circuit-breaker FKG must be opened. Thereafter, the busbar switch must be opened, and only after that can each of the grounding switches be closed.
For safety reasons, it is therefore necessary to prevent those switch apparatuses being actuated manually in a manner that does not comply with the above order.
OBJECT AND SUMMARY OF THE INVENTION
The object of the invention is to propose a device using locks to interlock the manual actuation of a switch having a handle inlet, and use locks having keys to authorize the switch to be actuated manually in a certain actuation sequence so as to cause the switch to pass from a first switching position to a second switching position.
According to the invention, the device comprises a first lock and a second lock each operable by means of at least one key capable of being withdrawn from the corresponding lock or of being engaged in said lock only when the lock is in its locked position, a set of cams whose rotation is tied to actuation of the switch and which act on the bolts of said locks to prevent the first lock from being operated so long as the second switch is not in its second switching position and to prevent the second lock being operated by its key as soon as the second switch no longer occupies its first switching position, both locks being disposed in such a manner that their respective bolts, when in the advanced position, close the handle inlet of the switch, the bolt of the first lock being in its retracted position and the bolt of the second lock being in its advanced position when the switch is in its first switching position.
Such an interlock device makes it possible to ensure that manual actuation of the switch is blocked at two levels. In order to be able to actuate a switching apparatus fitted with a device of the invention, it is necessary firstly to actuate the second lock so as to disengage the handle inlet by using a first key which can come from an interlock device associated with a switching apparatus that must be actuated before the switch in question. After the switch has been actuated with the help of the handle so as to cause it to pass into its second switching position, the handle must be removed in order to be able to actuate the first lock. After that operation, manual control of the switch is inhibited, and the key coming from said first lock can be used to unlock another interlock device associated with another switch apparatus that must be actuated manually only after the switch has been actuated. Consequently, with such an interlock device, it is possible to constrain an operator to follow a logical process when manually actuating a set of switch apparatuses.
As explained below, interlocking the switch apparatuses shown in
FIG. 6
with a set of interlock devices of the invention requires the use of only seven different keys. By making use of conventional mechanical locks, this device contributes to achieving interlocking of the switch apparatuses in a manner that is reliable, simple, and of low cost. Such a device can easily be adapted to provide interlocking between a generator circuit-breaker and a switch that has three switching positions, the switch possibly also constituting an injection switch.
REFERENCES:
patent: 2298234 (1942-10-01), Rugg
patent: 3174003 (1965-03-01), Armstrong
patent: 3206567 (1965-09-01), Grimm
patent: 3822368 (1974-07-01), Salzman et al.
patent: 4280035 (1981-07-01), Settlemire
patent: 5061199 (1991-10-01), McClead
patent: 5408213 (1995-04-01), Ungarsohn
patent: 527559 (1927-07-01), None
patent: 1 276 174 (1968-08-01), None
patent: 1 365 484 (1964-05-01), None
Alstom
Friedhofer Michael
Sughrue Mion Zinn Macpeak & Seas, PLLC
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