Phase control switch apparatus

Details Phase control switch apparatus Phase control switch apparatus

2000-11-22

2002-12-10

Huynh, Kim (Department: 2836)

Electricity: electrical systems and devices

Control circuits for electromagnetic devices

Including means for using, or compensating for, the induced...

C361S076000, C361S085000, C361S079000, C361S035000, C361S038000, C361S093100

Reexamination Certificate

active

06493203

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a phase control switch apparatus for controlling open/close (break/make) timings of a breaker connected to the power transmission system to thereby protect reactive loads or reactor components such as transformers, shunt reactors, capacitor banks (CB) and the like connected to the electric power system against an exciting rush current, a transient surge current or the like which takes place upon opening/closing of the breaker and which exerts adverse influences to the reactive load. More specifically, the present invention is concerned with a switchgear apparatus equipped with a phase-based break/make controller designed for suppressing the transient currents mentioned above to a possible minimum by controlling optimally the timings at which the breaker is to be closed.
2. Description of Related Art
Switchgear such as the breaker is generally equipped with a break/make timing control apparatus for the purpose of suppressing the exciting rush current, transient surge voltage or the like which occurs upon closing of the breaker by controlling the closing time point or timing of the breaker by taking into account the arcing time and like influential factors.
For having better understanding of the present invention, description will first be made in some detail of the conventional phase control switch apparatus (break/make timing control apparatus) known heretofore.
FIG. 24
of the accompanying drawings shows a structure of a hitherto known break/make control apparatus for a breaker typifying the switchgear together with the standard waveforms of R-, S- and T-phase supply voltages in breaker contact closing operation as well as operation timings of the breaker. Parenthetically, this apparatus is disclosed in Japanese. Patent Application Laid-Open No. 156820/1991 (JP-A-3-156820).
Referring to
FIG. 24
, reference numeral
10
denotes generally a transformer connected or wired in a Y-connection with a neutral point being connected to the ground potential, and numeral
50
denotes generally a breaker having arc-extinction chambers
52
a
,
52
b
and
52
c
within which contacts are disposed. For making it possible to perform open/close (break/make) operations for these contacts independently of one another, the contacts are equipped with respective actuator devices
54
a
,
54
b
and
54
c
. Further, in
FIG. 24
, reference characters
72
a
,
72
b
and
72
c
denote voltage measuring devices designed for measuring R-, S- and T-phase supply voltages, respectively, and numeral
80
denotes generally a phase-based break/make controller provided for the breaker
50
. The phase-based break/make controller
80
is comprised of a reference phase detecting unit
82
and an arithmetic processing/operation control unit
81
.
Description will now turn to operation of the breaker and the phase control switch apparatus.
The R-, S- and T-phase supply voltages are measured by the voltage measuring devices
72
a
,
72
b
and
72
c
, respectively, the output signals thereof being transmitted to a reference phase detecting unit
82
incorporated in the phase-based break/make controller
80
. The reference phase detecting unit
82
is designed for detecting the zero-point cycles of the R-, S- and T-phase supply voltages, respectively, to thereby determine the voltage-zero point which is to serve as the standard or reference time point T
standard
.
Upon reception of make (close) command for closing the breaker
50
, the arithmetic processing/operation control unit
81
constituting a part of the phase-based break/make controller
80
determines arithmetically a closing or making operation time t
close
and a pre-arcing time t
prearc
as predicted from the ambient temperature of the actuator devices, operating forces thereof and voltage measurement data, whereon the predicted closing operation time t
close
is subtracted from a time period intervening between the preset R-, S- and T-phase closing (making) target time point T
target
(e.g. electrical angle of 90° for voltage peak) and the reference time point T
standard
while adding the pre-arcing time t
prearc
, to thereby determine an operation synchronizing time period t
cont
.
Upon lapse of the operation synchronizing time period t
cont
from the reference time point T
standard
, the arithmetic processing/operation control unit
81
of the phase-based break/make controller
80
supplies the close or make signals to the individual actuator devices
54
a
,
54
b
and
54
c
, respectively, to thereby control the closing or making operations for the contacts disposed within the arc-extinction chambers
52
a
,
52
b
and
52
c
independently of one another so that these contacts can be closed independently each at a predetermined electrical angle which allows the switching surge phenomenon or event (i.e., surge current occurring upon closing) to be suppressed to a minimum.
Such closing or making operation of the breaker
50
performed at the voltage peak through the control procedure or sequence described above is adopted in many practical applications for closing various load apparatuses and equipment such as exemplified by transformers or shunt reactors in the state in which substantially no residual magnetic flux exists and which is thus favorable to suppression or avoidance of the switching surge event as well as for closing capacitor banks and transmission lines in the no-load state in which the switching surge phenomenon or event can be suppressed by closing the breaker
50
at the voltage-zero point.
As is apparent from the above, the closing control for transformers, shunt reactors or the like has conventionally been performed in the state where substantially no residual magnetic flux exists, allowing thus the switching surge taking place transiently upon contact closing to be suppressed by closing the breaker
50
at a voltage peak point. In reality, however, in case the residual magnetic flux is present in the core of the transformer or shunt reactor, great difficulty is encountered in operating the breaker
50
at the closing time point which is optimal for suppressing the switching surge event, giving rise to a problem.
SUMMARY OF THE INVENTION
In the light of the state of the art described above, it is an object of the present invention to provide a phase control switch apparatus which is capable of suppressing transient switching surge phenomena by operating or actuating the breaker at an optimum making or closing time point determined on the basis of the residual magnetic flux predicted for each phase of the transformer, the shunt reactor or the like reactive load notwithstanding of existence of the magnetic flux in the core thereof. Parenthetically, it should be pointed out that such making or closing control of the breaker which can suppress the transient surge and the like phenomena is generally considered to be difficult in the case where the residual magnetic fluxes exist in the core of the transformer, the shunt reactor or the like reactive load.
In view of the above and other objects which will become apparent as the description proceeds, there is provided according to an aspect of the present invention a phase control switch apparatus which includes a breaker connected to a reactive load connected to a three-phase electric power system in A-connection or alternatively in Y-connection with a neutral point being connected directly to the ground or alternatively not connected to the ground, the breaker being designed to break a fault current and a load current flowing through the reactive load or make the reactive load closed to the three-phase electric power system for excitation thereof, a voltage measuring means for measuring phase voltages on a phase-by-phase basis, a current measuring means for measuring inter-contact currents at an output side of the breaker, an actuating means for effectuating open/close operations of contacts of the breaker independently on a phase-by-phase basis, a temperature measuring means disposed in the vicinity of t

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