FIELD OF THE INVENTION
The present invention relates, in general to transformer testing. The present
.invention in particular relates to automated test rig/ jig/ testing device for
transformer testing. More particularly, the invention relates to a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits.
BACKGROUND OF THE INVENTION
Power transformers play an important role in transmission and distribution of
power. Power transformers form a critical link in the supply of power from the
generation source to the users of the utility. Failure of a power transformer often
means power loss to a number of consumers, therefore, transformer reliability is
a very important parameter. In addition to transformer reliability, energy
companies are typically very concerned about cost and efficiency of the power
transformers.
To meet the market demand, transformer manufacturers attempt to design
reliable and efficient power transformers. Power transformer design, however, is
a very complex process. There are probably hundreds of design parameters that
affect the cost performance (e.g. reliability, efficiency, etc) of a transformer.
Moreover, there are many manufacturing steps for a transformer, each of which
could affect the transformer performance. For example, if a transformer is
manufactured with a piece of equipment that is out of calibration, it may fail to
meet a performance specification. Because of the complexity of transformer
design and manufacture, it is very difficult to troubleshoot the root because of a
test failure and to determine a solution to address the test failure.
Transformers are tested by their manufacturers and the generation and
transmission authorities. The typical test parameters may include polarity,
phase relation, core loss, load loss, and transformer ratio.
However, there is no universal testing procedure followed by the testing
agencies. Different standards are followed and sometimes transformer
manufacturers implement their own custom test sequences. Many times, the
customer requires the manufacturer to follow a certain test sequence and with
many different customers, changing test sequences after every order is not an
easy task for the manufacturer's transformer testing facility. Moreover different
systems are typically needed to implement different tests.
Automated testing devices to test the transformers according to a test program
having a predetermined sequence of test instructions, are known. In other
words, the known test devices execute a test program in fixed sequence of test
instructions during the testing that cannot be varied with the requirements. For
example, if the test program selects a transformer test which is programmed to
first run a winding resistance test and then a voltage ratio test at a certain set of
parameters, then each time the transformer test is selected, the winding
resistance test is performed first and the voltage ratio test is performed second.
Thus, the sequence of test instructions is arranged such that a sequence of test
instructions specifying a winding resistance test is listed before a sequence of
test instructions specifying a voltage ratio test. The disadvantage of having a test
program with a fixed sequence of test instructions is that the user does not have
the flexibility of editing or creating a particular sequence to optimize the
transformer test program.
US Patent No.6,788,077 discloses a system and method for creating, editing,
and/or executing a test program for testing a transformer. The system includes
an input that allows the user to select the desired test instructions and preexisting
sequences of test instructions to create or edit a test program having a
sequence of test instructions. The processor executes the test program by
generating commands that are performed in a predetermined order.
Publication No. CN 202330594 describes an intelligent distribution transformer
terminal computer programmed test platform, characterized in that it comprises
a control computer and the test bench, the test bench equipped with a standard
three-phase power source, three-phase standard table, a small test signal
terminal interface board, a pulse signal generator, power test module, the DC
output module and a plurality of communication interfaces test bench, test bench
control computer via the communication interface, respectively, with the threephase
standard power source, three-phase standard meter, power test module,
the DC output module, pulse signal generator and small signal interface board to
connect the terminal test, three-phase power source with a standard threephase
standard meter connections.
Publication No. CN 102830311 teaches a transformer testing system for
automatically testing a transformer. The transformer testing system comprises a
conveying system and a detection system.
Publication No. CN 101382575 provides an automatic test system of an electronic
transformer, which comprises a machine cabinet, a high-low voltage switching
box, a programmable high-voltage tester, a computer, a displayer, a
programmable alternating current power supply, a keyboard, an indicator light, a
loading plate and a relay that are sequentially connected from down to up and
arranged in the machine cabinet, the high-low voltage switching box is installed
with a position sensor; the automatic test system of the electronic transformer
obtains test data by using the computer for controlling a dada acquisition card,
calculates the test data by using the computer, and then obtains the result for
judging the good and bad of the tested product; the computer has DAQ and DIO
serial ports.
Publication No. CN 2601406 suggests a computer control transformer test bench
for testing the performance of a transformer and technical energy saving. The
device is composed of a computer display, a keyboard, a printer worktable and a
cabinet, wherein the cabinet is provided with the industrial computer, a DC
resistance test module and a transformation ratio test module, and is composed
of a loss test module and a loss test control box.
Publication No. CN 203117358 describes an intelligent tester for secondary
polarity of a four-star-shaped voltage transformer. The intelligent tester for
secondary polarity of a four-star-shaped voltage transformer automatically
determines whether secondary side wiring of the four-star-shaped voltage
transformer is correct and the error type, and is rapid and accurate in test,
convenient to operate, and direct in display, thereby substantially improving
work efficiency, and reducing potential safety hazards.
Publication No. CN 102749607 discloses an electronic current transformer test
platform comprising a PC (Personal Computer) test system, a comprehensive
data interface, wiring terminals, current display screens, a current regulation turn
knob, a power switch, a trolley body and universal wheels, wherein the PC test
system is mounted on a side face of the trolley body, the comprehensive data
interface is located at a side face of the trolley body, the current display screens
are arranged at middle positions of the upper face of the trolley body, the wiring
terminals are arranged at one side of the upper face of the trolley body, and the
current regulation turn knob and the power switch are arranged at the other side
of the upper face of the trolley body.
Publication No. CN 101344566 describes a test apparatus and a test method
used for testing the distortion of a coil of a power transformer. The apparatus
comprises an upper computer, a test unit, a DDS sweeping a signal generator
unit, a wide-frequency power amplifier unit and a power supply system.
US Patent No. 5,264,799 teaches an apparatus for automatically testing the
performance of a power transformer without requiring a testing operator
repeatedly to disconnect-and-connect the power supply lines during the testing
process so as to avoid the risk of high voltage electric shocks.
Publication No. CN 203217023discloses a motor and transformer microcomputer
integration test stand. The motor and transformer microcomputer integration
test stand has functions of intelligent control and measuring, automatically
completes functions of test data acquisition, calculating, storage and historical
report check, automatic formation of a test report and printing, simplified a
tedious wiring process in a test, effectively improves work efficiency and reduces
an error ratio in the test.
Publication No.CN 102565562 teaches a comprehensive testing device for an
electrical test of a transformer. The whole device is provide with a set of working
power supply, wherein a foreground processor of a central processing unit (CPU)
system is used for the data acquisition work of three data acquisition systems
and controls the work of a relay switching system; and a background computer
finishes man-machine interaction work, manages data and outputs a testing
report.
Publication No. CN 103439682 describes a current transformer composite error
testing technology and provides a portable current transformer composition error
testing device and a method for testing a composite error of a current
transformer by utilizing the portable current transformer composite error testing
device.
Reference may be made to prior non-patent literature entitled "TTRIOO handheld
single phase turns ratio test set" by Megger Group Limited which talks about
a handheld, robust, lightweight and battery operated instrument which tests
turns ratio, phase displacement, excitation current, vector group, winding
resistance and polarity. The device also has alphanumeric keyboard.
8
Reference may be made to non-patent literature entitled "Technical & Testing
equipment" by O'Hara Engineering that talks about a lightweight instrument for
performing excitation, ratio, polarity and winding resistance tests on current
transformers (CYs) as well as burden-impedance measurement.
Reference may be made to known non-patent literature entitled "Multifunctional
primary test system for substation commissioning and maintenance" by Omicron
Electronics that talks about system for automated testing of power transformers
such as testing of ratio, burden, polarity and winding resistance etc.
Accordingly the prior art describe transformer testing devices that include
multiple steps or involve different equipments. Also the testing device reqires the
transformer to be disposed into the device making it a time consuming and
laborious job.
A system for non-contactably perform multiple tests of major operating
parameters of transformers with adjustable test sequence and test limits.
The present invention provides a customized transformer rig/jig device whose
testing limits and test sequence can be programmed by an authorized personnel
and which is protected by the mean of an authentication system. Transformer
testing rig provides the complete protection/isolation for any wrong connections.
OBJECTS OF THE INVENTION
It is therefore an objection of the invention to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits.
Another object of the invention is to propose a system for non-contactably
perform multiple tests of major operating parameters of transformers with
adjustable test sequence and test limits which is easy to operate.
Yet another object of the present invention to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits which is capable of testing a
transformer with different winding configurations.
Still another object of the present invention is to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits which is enabled to test the no-load
current, power including power factor of the transformer.
A further object of the present invention is to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits which can be adjusted during the
testing corresponding to the rating of transformers.
10
A still further object of the invention is to propose a system for non-contactably
perform multiple tests of major operating parameters of transformers with
adjustable test sequence and test limits which is capable for current-controlled
determination of characteristic of the transformers including the power supplies.
Yet further object of the present invention is to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits which eliminates substantial
number of devices needed for testing of the transformers.
Another object of the present invention is to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits which simplifies the procedure of
testing the transformers.
Another object of the present invention is to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits which is enabled to adjust the limits
of testing parameters including testing sequence applicable to various types and
capacities of transformers.
Another object of the present invention is to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits which can generate a testing profile
for the transformer to be tested and maintain a record file.
11
Another object of the present invention is to propose a system for noncontactably
perform multiple tests of major operating parameters of transformers
with adjustable test sequence and test limits which provides a protection to the
testing rig of the testing system against connection - error and simultaneously
suggests the desired connection.
SUMMARY OF THE INVENTION
Accordingly, there is provided a system for non-contactably perform multiple
tests of major operating parameters of transformers with adjustable test
sequence and test limits which allows for automatic testing of different
parameters of multiple types of transformers such as but not limited to polarity,
no-load current, no-load power, no-load power factor including correctness of
the winding ratio for variable AC voltage.
In an embodiment of the present invention, the system incorporates a switching
means which permits the windings of the transformer under test to be
sequentially connected to a test rig/jig of the testing system.
In another embodiment of the present invention, the system includes an
alphanumeric input/output devices such as but not limited to a keyboard so that
user can change inputted technical parameters as per rating of the transformer
into the system.
12
In yet another embodiment of the present invention, the user can set a lower
and upper limit of turns/ winding ratio. No-load current of all windings on
particular voltages, DC resistance of all windings, no-load power factor, no-load
power consumption, ratio error and phase angle error in the steady state, errors
in boundary conditions, and verification of the design for low leakage flux.
In still another embodiment of the present invention, the order of execution of
each test instructions is stored and the transformer test sequence is generated
based on the order.
In a further embodiment of the present invention, indications are provided to
know the test status of the transformer i.e. pass, rejected or testing in progress.
In a still further embodiment of the present invention, a display is provided to
show the status of parameters of the transformer.
In an yet further embodiment of the present invention, a communication
interface is provided for local and remote monitoring of the system.
In another embodiment of the present invention, a data logging and RTC is
provided to know hour wise, current and daily date of transformer test rig/jig
testing device.
In yet another embodiment of the present invention, a user selection facility is
provided to extract the data.
13
In still another embodiment of the present invention, the system comprises
separate wires which can be connected directly to the transformer terminals
through clips which make it easer for testing in field conditions.
In yet another embodiment of the present invention, a transformer testing profile
can be generated which contains but not limited to upper lower limits, testing
sequence by an authorized personnel.
In yet another embodiment of the present invention, an authentication means is
provided for example, a biometric device which also keeps the record.
In yet another embodiment of the present invention, the system provides
complete protection/isolation against wrong electrical connections at the end of
the testing transformer or at end of the transformer test rig and also provides a
solution/step to be taken to avoid wrong connections.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
It is to be noted, however, that the appended drawings illustrate only typical
embodiments of this invention and are therefore not to be considered for limiting
of its scope, for the invention may admit to other equally effective embodiments.
Figure 1 illustrates an exemplary system in accordance with the persent
invention used for testing transformers;
14
Figure 2 illustrates a flow chart according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a fully automated transformer testing system for
conveniently testing different parameters of square wave as well as sine wave
transformer of different ratings such as XVA, to YKVA. The system enables easy
input of ail relevant test parameters. The overall testing procedure is broken
down into different test sequences which run automatically.
The transformer testing system includes an AC source 1, variable AC voltage lA,
a switch 2, a micro controller 3, a display 4, an indicator 5, a communication
interface 6, a REC 7, a transformer to be tested 8, one each primary and
secondary signal generator 9, 10, a data logger 11, a user interface 13 and
additionally/optionally an ampere meter for testing sine wave power transformer
to power few power backup systems. A switch mode power supply 13 with fixed
DC voltage and current is introduced to measure winding resistance and conduct
the HV test of the transformer.
A transformer (8) that is to be tested is disposed between the switch (2) and the
controller (3). The testing rig/ jig/ testing system further includes separate wires
which can be connected directly to the transformer (8) terminals through clips
which eliminates the need to dispose the transformer (8) into the testing system.
The switch (2) is coupled to a power supply (1) and provides power to the
transformer (8) during the test. If the wires are connected to wrong terminals,
the transformer (8) is protected by automatically switching the power off.
15
The switch (2) is controlled by the controller (3) to provide power from the
power supply (1) to the transformer (8) being tested. The measured data are
transferred from the transformer to the processor (3) processes the
measurements and stores the result (s) in a memory device or elsewhere. The
memory devices is selected from the group such as but not limited to RAM, ROM,
or mass memory devices such as a disk drive, and can be separate or reside
within the same memory device. Preferably, the memory comprises transformer
specifications, and the memory device receives and stores the results of the
transformer test, used for future study and analysis.
The transformer test program is customized by creating or editing a new
sequence of test instructions from individual test instructions or other preexisting
sequences of test instructions. A user is able to create sequences for
testing a transformer and store these sequences for future use. The user
customizes the testing liSmits of the transformer to be tested, which are
protected by the means such as but not limited to the password or biometric
system so that only an authorized person is able to change the limits. An input
system such as but not limited to the keypad/ keyboard is provided with the
automatic transformer test system, the user will be able to set the upper - lower
limits of turns/ winding ratio, no load current of all windings on particular
voltages, DC resistance of all windings, no-load power factor, no-load power
consumption, ratio error and phase angle error in the steady state, errors in
boundary conditions, and verification of the design for low leakage flux. There
16
will be a record of the person who changes the limits along with date time and
old values. The system restores factory default setting automatically. User is able
to create new transformer profile with assigning transformer capacity, testing
limits both lower and upper, test sequence.
The transformer test system is able to detect the wrong connections of the
transformer (8) to be tested. In case if transformer's primary windings,
secondary winding or any auxiliary winding connections get reversed then test
rig will automatically detects it and stops the test, by changing the sequence of
testing. The testing sequence starts with connections checking by applying
voltage on low voltage winding side instead of high voltage on high voltage
winding, by virtue of which if there are any wrong connections, then applied low
voltage will not create any effect on the winding and on circuitry of the system.
After applying low voltage on the low voltage winding, the voltage is measured
on the each winding and tested for a lower limit, if connections are ok then it will
pass the protection test and will proceed further, if connections are wrong then
low voltage will be applied to high voltage winding side and very less voltage will
be applied to high voltage winding side and very less voltage will be generated
on low voltage winding side which will not reach the lower limit, so it will fail in
protection test and testing will be stopped.
17
Automated transformer test device contains a pneumatic linear movable fixture.
A linear movable platform is provided with a plurality of carrier tracks equally
spaced around the periphery of the linear platform; each one of the carrier tracks
is adapted to carry a transformer to be tested and is provided with a
corresponding connecting points. There is movable platform, which is having a
pneumatic control and have electrical connections from the test rig.
Any number of transformers are loaded on the linear platform and vertical
platform is in upward direction, as soon as start switch is pressed, linear platform
sides to match the vertical platform position, vertical platform senses the position
of linear platform carrying transformer to be tested and make a contact with
linear platform and transformer test rig senses the proper fitment of platform
and starts testing.
After testing stops, vertical platform moves in upward direction and linear
platform slides to match next transformer with vertical platform, and new
transformer will be loaded on the vertical platform. Once all linear platform slides
are over, then it works in reverse direction.
Test instructions that can be used in building test sequences include, such as but
not limited to, turns/ winding ratio test, polarity, no-load current, no-load power
factor, no-load power consumption. Parameters that can be set to act on these
tests include, but are not limited to, test voltage, test duration, ramp profile, and
temperature range, as further described below.
18
The user may customize the test program by selecting the desired test
instructions and/or pre-existing sequence of test instructions and then defining
the order of execution of each of the test instructions selected by inputting entry
commands into the processor via a use interface. The user can change the
values of test parameters as per the transformer rating using alphanumeric key
board. The user can also set the lower and upper limit of the no-load current
value.
The system presents the user with messages on the status of the testSs,
presenting the errors and the time at which they occurred. The messages are
displayed on the display device, telling the user the status of the test, when it is
beginning to be tested, if it was completed successfully, or whether an error
occurred. The time is desirably presented also so that the user knows what time
an error occurred or a test started, what time it ended, or what time an error
occurred. Visual indications are provided to know the status of the transformer,
whether it is "pass", "rejected", or "testing in progress".
The system of the present invention also includes a communication interface for
local and remote monitoring of the device. The data information is sent to the
remote monitoring station using a wired/wireless communication protocol. The
remote monitoring station constitutes a remote communication interface with a
sensor module and a user interface and display.
19
Communication includes the parameters but limited to slave ID, type of rig,
transformer model selected, current status of Rig, function code, test status, no.
of transformer tested, no. of pass transformer, no. of fail transformer, date and
time of each test, parameters of each test result which includes but not limited
to winding voltage, winding ratio, no load current of each winding on particular
voltage, winding resistance of each winding, testing sequence, operator ID, cycle
time, checksum.
Date is also stored in the provided internal memory not limited to micro SD card,
EEPROM, FLASH and Pen Drive.
In an aspect, the information about such as without limitation the product under
test, test conducted is monitored through remote display inside the local
premises by using power line communication.
Transformer testing profile is created which contains but not limited to upper
lower testing limits, testing sequence by an authorized personnel. Authentication
is provided by the mean of but not limited to biometric system and keeps the
record. The device will provide complete protection/ isolation against the wrong
connections at the end of testing transformer or at end of transformer test rig
and also provides the solution / step to be taken.
Transformer test system can be up- graded on site. Multiple transformer test rig
is controlled by a single system using wired/wireless communication or multiple
systems can access single transformer test rig. Each transformer test rig carries
its current position and unique identity. Reports are generated based on but not
limited to day wise, weekly, monthly or yearly.
20
The system is further provided with "data logging" and RTC to know hour wise,
date wise, current and daily data of transformer test rig/jig/testing device and
user selection facility is also provided to know the data.
If a test fails during the test sequence, the test sequence is aborted, either
manually by an operator monitoring the testing or automatically by the system if
the testing criteria have been programmed to abort in such a case. The
transformer test rig/jig/testing device keeps track of units previously tested.
Previous test results are accessible from the memory device or wherever the
results may be stored.
The transformer test rig/jig/testing device of the present invention is preferably
suited to perform tests in the field, as well as in manufacturing facilities and
repair centers.
Numerous modifications and adaptations of the system of the present invention
will be apparent to those skilled in the art, and thus it is intended by the
appended claims to cover all such modifications and adaptations which fall within
the true spirit and scope of this invention.

WE CLAIM
1. A system for non-contactably perform multiple tests of major operating
parameters of transformers with adjustable test sequence and test limits,
the current transformers each having at least a primary winding and a
secondary winding, the system comprising: an alternating current (AC)
power source configured to supply an AC signal; a variable AC voltage
controller to generate a desired voltage; a switch coupled between a
micro - controller and the transformer to switch power to the controller
responsive to the control commands; a plurality of individual wires for
connection to transformer terminals, an alphanumeric keyboard to change
the imputed value of test parameters, an optional ampere meter for sine
wave transformers to power the power backup systems, a display device,
a visual indicator, a pneumatic linear movable fixture, a communication
port, a data logger with input means, a biometric or password protection
device, a RTC connected to the controller and a switch mode power
supply with fixed DC voltage and current to measure such as but not
limited to winding resistance and HV test of the transformers, wherein the
system is enabled to :
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17 Jill
create sequences by the user for testing a transformer and store these
sequences for future use; select the testing limits of the transformer to be
tested including the upper - lower limits of turns/ winding ratio, no load
current of all windings on particular voltages, DC resistance of all
windings, no-load factor, no-load power consumption, ratio error and
phase angle error in the steady state, errors in boundary conditions, and
verification of the design for low leakage flux, and generate new
transformer profile by assigning date relating to transformer capacity
both lower and upper testing limits and the test sequence.
2. The system as claimed in claim 1, wherein different lower and upper limit
of the no-load claimed in claim 1, wherein different lower and upper limit
of the no-load current value can be set for different transformer rating.
3. The system as claimed in claim 1, wherein the switch is selected from the
group consisting of static, electromechanical or manual switch.
4. The system as claimed in claim 1, wherein the display device exhibits the
status of the parameters of the transformer.
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5. The system as claimed in claim 1, wherein the visual indicator provides
the status of transformer testing including the final test result.
6. The system as claimed in claim 1, wherein said linear movable fixture is
provided with a plurality of carrier tracks equally spaced around the
periphery of the linear platform.
7. The system as claimed in claim 1, wherein the information about such as
without limitation the product under test, test conducted is monitored
through remote display inside the local premises by using power line
communication.
8. The system as claimed in claim 1, wherein the communication interface
allows local and remote monitoring of the test system.