A METHOD AND APPARATUS FOR VOLTAGE DIP AND INTERRUPTION
FIELD OF THE INVENTION
[0001] The present invention relates in general to methods and systems of
simulating field like conditions in a laboratory and, more particularly to a method and apparatus to simulate voltage interrupt and voltage dip conditions in a laboratory to understand its effect on electrical equipments like meters and to understand the behavior of meters in these conditions.
BACKGROUND OF THE INVENTION
[0002] In electrical distribution systems the equipments used, are subjected to
various electrical loads of varying magnitude, fluctuations and their combinations which do not follow a regular pattern. In order to improve the design and to study the effects of different conditions on electrical equipments, it is often necessary to create field like conditions in a laboratory.
[0003] Electrical equipments such as meters which are installed in electrical fields
undergo through different conditions like voltage failure, voltage fluctuation, voltage dip for a period of time. In order to test electrical equipment in a laboratory it is necessary to load the equipment with the loads similar to these conditions to study their effect on the working of the equipment.
[0004] Traditionally several systems and methods to simulate voltage interrupt
and voltage dip exists but they work with standard profiles only and do not allow to change the standard user inputs. Thus there exists a need of a method and apparatus which overcomes above mentioned drawbacks gives the user more flexibility to create various fields like conditions in a laboratory.
SUMMARY OF THE INVENTION

[0005] The present invention to a method and apparatus to simulate voltage
interrupt and voltage dip conditions in a laboratory to understand its effect on electrical equipments. The method according to an embodiment of the present invention comprises steps of switching the power supply ON, selecting to provide a standard input profile or a customized user input profile, entering the inputs based on the selection and applying the voltage interrupt and voltage dip conditions on the electrical equipment. The apparatus based on the above method comprises a power supply means, a means to receive user input, a micro-controller to process the user input, memory to store the user input and status of the apparatus, a firmware for receiving the user input from the micro-controller and applying the voltage interrupt and voltage dip conditions on the electrical equipment; and a display means for showing the user input and the status of the apparatus.
BRIEF DESCRIPTION OF DRAWINGS
[0006] FIG. 1 is a schematic diagram of method of simulating voltage interrupt
and voltage dip conditions in a laboratory according to an embodiment of the present
invention.
[0007] FIGS. 2(a), (b) and (c) shows the waveforms for voltage interrupt and
voltage dip as per standard IEC62052.
[0008] FIG. 3 shows the waveform for voltage interrupt used in, customized user
input profile according to an embodiment of the present invention.
[0009] FIG. 4 shows the waveform for voltage dip used in customized user input
profile according to an embodiment of the present invention.
[0010] FIG. 5 is a schematic diagram of apparatus of simulating voltage interrupt
and voltage dip conditions in a laboratory according to an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0011] Referring to FIG 1, a schematic diagram of method of simulating voltage
interrupt and voltage dip conditions in a laboratory according to an embodiment of the

present invention is shown. The method 100 starts with step 102 of switching the power
supply ON, which starts the apparus which workn on this method and also starts booting
the controller used.
[0012] In next step 104 the user has to select to provide a standard input profile or
a customized user input profile. Based on the slection the user need to enter the inputs
and the control correspondingly goes to step 106 or step 108 for standard user input
profile and customized user input profile.
[0013] In step 106 the standard user input profile is used as the user input for
creating the voltage interrupt and voltage dip conditions. The standard user input profile
comprises includes a voltage interrupt waveform and a voltage dip waveform as per
standard IEC62052 which are discussed in detail in the later section of this description.
[0014] In step 108 the user input is customized by entering various input
parameters. The customized input is also discussed in the following paragraphs in this
description.
[0015] In step 110 user input either from standard user input profiles or
customized user input profile is used for applying the voltage interrupt and voltage dip
conditions on the electrical equiment 12.
[0016] FIG. 2 shows the waveforms for voltage interrupt and voltage dip whe the
tests are carried out with pre-defined times and pre-define waveform with respect to
Metering Standards like IEC62052-11.
[0017] The X-axis 40 represents the time in time 't' and Y-axis 42 represents
voltage MJ\ In FIG. 2 (a), there is voltage interrupt i.e. voltage change AU= 100 % for 1
second and then it again comes back to original value and remains for 50 milli-seconds.
As it can be seen there are three interrupts of 1 second each. This forms a cycle for 'Test-
1' as per standard IEC62052.
[0018] In FIG. 2 (b), there is voltage interrupt i.e. voltage change AU= 100 % for
few milli-seconds 20 ms or 16.67 ms and then it again comes back to original value.
There is only one interrupt and its one cycle of rated frequency. This forms a cycle for
'Test-2' as per standard IEC62052.
[0019] FIG. 2 (c) shows the voltage dip situation, where the voltage dips to 50 %
of its original value i.e. voltage change AU= 50 % for 1 minute and then it again comes

back to original value. There is only one dip and it forms one cycle for 'Test-3' as per standard IEC62052.
Test condition as per Metering Standard: Voltage interruption at AT>100%,ls (Test-1)
Voltage interruption of AU=100%, one cycle at rated frequency (Test-2) Voltage Dips of AU=50% (Test-3)
[0020] In an embodiment of the present invention the user can select standard
user profile which comprises sequences which are combinations of the standard tests viz. Test-1, Test-2 and Test-3 as shown below. In case of Standard Profile, following are the selective test conditions:
Sequence-1 -> (Test-1)
Sequence-2 -> (Test-2)
Sequence-3 -> (Test-3)
Sequence-4 -> (Test-1, Test-2 and Test-3)
Sequence-5 -> (Test-1 Continuously)
Sequence-6 -> (Test-2 Continuously)
Sequence-7 -> (Test-3 Continuously)
Sequence-8 -> (Test-1, Test-2 and Test-3 Continuously)
[0021] Sequence-1, Sequence-2, Sequence-3 and Sequence-4 are one time
sequences i.e. after the execution the control goes back to step 104 of FIG.l. But Sequence-5, Sequence-6, Sequence-7 and Sequence-8 are continuous sequences and user intervention is needed to stop execution.
[0022] The customized user input profile has been developed based on
customer(electricity test requirements). For conducting Customize Profile based test , waveforms as shown in FIGs 3 and 4 is being followed.
[0023] FIG. 3 shows the waveform for voltage interrupt used in customized user
input profile according to an embodiment of the present invention. The X-axis 50 represents time 't' and Y-axis 52 represents voltage 'U\ The figure shows Power ON initially then there is voltage interrupt for a period of time called OFF TIME 'X', followed by recovery of voltage to its original value for a period of time called ON TIME 'Y' and this forms a cycle called 'CYK'. The cycle is repeated till the 'End Time' of the

voltage interrupt waveform cycle for the number of counts for which the cycle is selected
to repeat is reached.
[0024] The OFF TIME 'X' and ON TIME ' Y' can be changed in steps X-step and
Y-step correspondingly. User Inputs are as follows for the waveform for voltage interrupt
used in customized user input profile according to an embodiment of the present
invention:
Tablel

where ms= milli-seconds CYK will be executed for Count Value. For example if count=10 then CYK(with X and Y Value) will be executed for 10 times.
[0025] FIG. 4 shows the waveform for voltage dip used in customized user input
profile according to an embodiment of the present invention. The X-axis 60 represents time 't' and Y-axis 62 represents voltage percentage, 1 for 100 % voltage and 0 for no voltage, 0.5 indicates 50 % of the original voltage. The voltage is at its orginal value and then dips to 50 % for a period of time 'Td', then it recovers and comes back to 100% for a period of time 'To', which completes one cycle of voltage dip 'TYK'. The cycle is repeated for a number of time indicated by 'Dip Count'.
[0026] User Inputs are as follows for the waveform for voltage dip used in
customized user input profile according to an embodiment of the present invention:


[0027] In case of customized user input profile, following are the selective test
conditions:
Sequence-1 -> (Voltage interruption and X is variable) follows Table 1 Sequence-2 -> (Voltage interruption and Y is variable) follows Table 1 Sequence-3 -^ (Voltage interruption and X & Y both are variable) follow Table. 1 Sequence-4 -> (Voltage Dips) follows Table 2
For above Sequences the user inputs are as follows:
Sequence-1: (Voltage interruption and X is variable)
1 X (OFF Time) 10ms to 6000ms
2 Y (ON Time) 10ms to 6000ms
3 End Time 10ms to 6000ms
4 Count 1 to 100
5 X-Step 10ms to 6000ms
Sequence-2: (Voltage interruption and Y is variable)
1 X (OFF Time) 10ms to 6000ms
2 Y (ON Time) 10ms to 6000ms
3 End Time 10ms to 6000ms
4 Count 1 to 100
5 Y-Step 10ms to 6000ms
Sequence-3: (Voltage interruption and X and Y both are variable)
1 X (OFF Time) 10ms to 6000ms
2 Y (ON Time) 10ms to 6000ms
3 End Time 10ms to 6000ms
4 Count 1 to 100
5 X-Step 10ms to 6000ms
6 Y-Step 10ms to 6000ms
Sequence-4 -> (Voltage Dip)

1 Td 10ms to 6000ms
2 TO 10ms to 6000ms
3 Dip Count 1 to 100
After the execution of customized user input the control goes back to step 104 of FIG. 1.
[0028] FIG. 5 is a schematic diagram of apparatus of simulating voltage interrupt
and voltage dip conditions in a laboratory according to an embodiment of the present invention. The apparatus 10 is based on the method 100 comprises a power supply means 14 to the apparatus, a means 16 to receive user input 18, a micro-controller 20 to process the user input, memory 22 to store the user input and status of the apparatus, a firmware 24 for receiving the user input 18 from the micro-controller 20 and applying the voltage interrupt and voltage dip conditions on the electrical equipment 12 and a display means 26 for showing the user input and the status of the apparatus 10.
[0029] In a preferred embodiment of the present invention the power supply
means 14 is adapted to customize the fix value of voltage dip by using a step down
transformer. The power supply means 14 used includes a 240V A-C supply, a
transformer, a rectifier/ filter and regulator and is adapted to supply a DC output of 5V
and 24 V. The power supply is based on the transformer and it is a linear power supply.
[0030] In a further preferred embodiment of the present invention the means 16 to
receive user input include a keypad to enter the user input 18. It also includes a power ON/Off switch to start the apparatus 10.
[0031] In a further preferred embodiment of the present invention the micro-
controller 20 is adapted to be programmed as per the requirements of the user. A Programmable Interface Controller PIC 16F877A and IC ULN2803/2804 is used as the micro-controller 20.
[0032] The memory 22 to store the user input 18 and status of the apparatus is
adapted to restart the apparatus 10 from the same condition where it got interrupted due to accidental power failure. It is the internal EEPROM ( Electrically Erasible Programmable Read Only Memory) of the PIC 16F877A.
[0033] The firmware 24 which includes relays and other electrical devices
receives the user input 18 from the micro-controller 20 and applies the voltage interrupt

and voltage dip conditions on the electrical equipment 12 which is used fro testing. The
meters are tested using this method an apparatus.
[0034] The display means 26 is a LCD 16x2 and it shows the user input, the loads
of the firmware and the status of the apparatus 10 at any given time.
[0035] In a preferred embodiment of the present invention the apparatus 10
includes micro-controller PIC16F877A, memory 22 ULN2804, display means 26 LCD
16x2.
[0036] The apparatus 10 can be programmed as many times as needed by using
the standard and customized user input profiles. The IDE used is MPLAB Ver7.50 and C
Compiler used is Hi-tech PICC Ver 8.02PL1 in a preferred embodiment of the present
invention.

We Claim:
1. A method of simulating voltage interrupt and voltage dip conditions in a laboratory
for testing electrical equipment, comprising the steps of:
- switching the power supply ON;
- selecting to provide a standard input profile or a customized user input profile;
- entering the inputs based on the selection; and
- applying the voltage interrupt and voltage dip conditions on the electrical equipment.

2. The method according to claim 1, wherein the standard user input profile includes a voltage interrupt waveform and a voltage dip waveform with pre-defined times as per Metering Standards such as IEC62052-11.
3. The method according to claim 2, wherein the method is adapted to use the voltage interrupt waveform and the voltage dip waveform as per standard IEC62052, independently and in combinations thereof.
4. The method according to claim 1, wherein the customizing the user input profile comprises the steps of:

- creating a voltage interrupt waveform by specifying a Voltage OFF Time(X), a Voltage ON Time(Y), a X-step size, a Y-step size,a End Time of the voltage interrupt waveform cycle and counts for which the voltage interrupt waveform cycle is to be used; and
- creating a voltage dip waveform by specifying a time period of voltage dip, a time period of original voltage and counts for which the voltage dip waveform is to be used.
5. The method according to claim 4, wherein the Voltage OFF Time(X) and the
Voltage ON Time(Y), the X-step size, the Y-step size, the End Time of the voltage
interrupt waveform cycle and counts for which the voltage interrupt waveform cycle is
to be used, are varied independently while keeping other parameters constant to form
customized user input profiles.

6. The method according to claim 4, wherein the voltage dip is adapted to be
customized at a fixed value.
7. An apparatus based on the method according to preceding claims, comprising:
- a power supply means to the apparatus;
- a means to receive user input;
- a micro-controller to process the user input;
- memory to store the user input and status of the apparatus;
- a firmware for receiving the user input from the micro-controller and
applying the voltage interrupt and voltage dip conditions on the electrical
equipment; and
- a display means for showing the user input and the status of the apparatus.
8. The apparatus according to claim 7, wherein the power supply means is adapted to
customize the voltage dip by using a step down transformer.
9. The apparatus according to claim 7, wherein the means to receive user input
include keys to enter the input and start the apparatus.
10. The apparatus according to claim 7, wherein the memory to store the user input
and status of the apparatus is adapted to restart the apparatus from the same condition
where it got interrupted due to accidental power failure.