TECHNICAL FIELD
[001] The present disclosure described herein, in general, relates to an automatic
changeover switch, and more particularly to a changeover switch based on voltage passage
indicator.
BACKGROUND
[002] Conventionally a consumer with dual power source of energy use ring main
unit (RMU) with potential transformer. However, even if dual power supply is available in the
RMU, manual intervention is required in case of supply failure to do the changeover.
Presently, it takes about 30 minutes for the changeover.
[003] It has been observed that in process industries during the supply failure there is
a line rejection of around 15% before the restoration of power supply through Diesel
generator.
[004] Many solutions have tried to overcome the present drawbacks. In a prior art a
Make-before-break selector switch is disclosed. Make-before-break switch discloses a
switching mechanism wherein second switch is made before the first connection is lost.
[005] The other solutions suggested disclose a phasing and indicator arrangement for
a switchgear or the like that responds to electrical sources and provides voltage indicator
functions, phasing determinations, and self-test features.
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SUMMARY
[006] This summary is provided to introduce concepts related to systems and
methods for an automatic changeover switch and the concepts are further described below in
the detailed description. This summary is not intended to identify essential features of the
claimed subject matter nor is it intended for use in determining or limiting the scope of the
claimed subject matter.
[007] In one implementation, a system for auto-changeover switch is disclosed. The
system may comprise a voltage passage indicator to compare voltages from at least two power
sources. Further, the system may comprise a ring main unit (RMU) having a capacitive
brushings. The RMU is for 11kV of load. The present system may further comprise a
potentiometer, wherein the potentiometer is set to a reference value between 80 to 90 volts.
[008] In another implementation a method for auto-changeover is disclosed. The
method may comprise steps of determining voltage in a first power source, isolating the first
power source and setting connection to open, and isolating a second power source and setting
connection to close. The voltage is may be determined by capturing, voltage from a capacitive
bushings from the RMU. Voltage determining may further comprise of comparing the voltage
to a preset limit using a potentiometer.
BRIEF DESCRIPTION OF THE DRAWINGS
[009] The detailed description is described with reference to the accompanying
figures. In the figures, the left-most digit(s) of a reference number identifies the figure in
which the reference number first appears. The same numbers are used throughout the
drawings to refer like features and components.
[0010] Figure 1 illustrates a circuit diagram of the automatic changeover switch.
DETAILED DESCRIPTION
[0011] System and method for an automatic changeover switch are disclosed.
[0012] Referring to Figure 1, a circuit diagram (100) of the automatic changeover
switch is illustrated. The circuit diagram discloses a Break-Before-make circuit. According to
an embodiment of the present disclosure the auto-changeover switch detects voltage from at
least two source, a first source and a second source. In case power supply fails form the first
source and power supply is available in the second source changeover process maybe
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initiated. According to present disclosure the first source isolator, referred to as Iso-1 in the
figure 1, is open first. While simultaneously the second source isolator, referred to as Iso-2 in
the figure1, is closed. This process ensures safety and paralleling of two alternate sources
which may result in prevention of fault.
[0013] In another embodiment of the present disclosure to sense or determine power
supply in the at least two power, a capacitive voltage bushing is mounted in the ring main unit
(RMU) is used. The capacitive voltage bushing drives a voltage passage indicator to display
the available power supply. Further, a potentiometer may be used to compare the at least two
power source, wherein the sensitivity of the potentiometer may be set to pre-defined value,
which may be 80-90V. The RMU of the present disclosure can be of 11kV.
[0014] However, the capacitive bushings has very low burden, therefore they may not
be able to pick up a contractor/connector. To overcome the limitation a direct amplifier circuit
that could sense voltage of VPI and compare the voltage with the preset setting may be used.
[0015] According to the present disclosure, once the voltage crosses the preset setting
the output relay for each phase indication may be enabled. The direct amplifier circuit will
pick the output contractor when all the phase indication are enabled. With the help of these
contacts supply changeover is done.
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I/We claim:
1. A system for auto-changeover switch comprising:
a voltage passage indicator;
a ring main unit (RMU) consisting capacitive brushings, wherein the RMU is 11kV;
and
at least two power source comprising a first power source and a second power source.
2. The system of claim 1, further comprises a potentiometer, wherein the potentiometer is set
to a reference value between 80 to 90 volts.
3. A method for auto-changeover, the method comprising:
determining voltage in a first power source;
isolating, the first power source and setting connection to open ; and
isolating a second power source and setting connection to close.
4. The method of claim 3, wherein the voltage is determined by capturing, voltage from a
capacitive bushings.
5. The method of claim 3, wherein determining of voltage further comprises comparing the
voltage to a preset limit using a potentiometer.