FORM 2
THE PATENTS ACT, 1970 PROVISIONAL SPECIFICATION
(See Section 10)
AN ELECTRONIC TESTING DEVICE TO SIMULATE THREE
PHASE AC REAL TIME FIELD WAVEFORMS AND TO VERIFY
RESPONSE OF CIRCUIT BREAKER
Numbered as dated
INVENTORS:
a) PRATIK SHAH
APPLICANT:
M/s. LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No 278, Mumbai, 400 001, Maharashtra,
INDIA

AN ELECTRONIC TESTING DEVICE TO SIMULATE THREE
PHASE AC REAL TIME FIELD WAVEFORMS AND TO VERIFY
RESPONSE OF CIRCUIT BREAKER
A) TECHNICAL FIELD:
The present invention generally relates to an electronic testing device and more particularly to a portable electronic testing device which simulates three phase AC real time field waveforms and verifies response of electronic circuit breakers.
B) BACKGROUND OF THE INVENTION:
Circuit breakers are designed to protect electrical apparatus from damages due to excessive current flow. New generation circuit breakers are capable of protecting the connected load over a wide range of protection aspects like thermal over load, short circuit, directional short circuit, under current, current unbalance, voltage unbalance, instantaneous, under voltage, over voltage, earth fault etc. Electronic breakers are also providing protections for harmonic distortion, under frequency, over frequency, reverse power etc. Protection parameters are programmable, i.e user can configure the breaker with multiple pick up levels and trip time delays.
When circuit breakers are connected to the electrical distribution network, maintenance and verification activities are required at a regular interval to check whether breakers are working properly or not. To verify the response characteristic of a breaker for a particular


protection it is desirable to simulate the required fault condition and verify breaker operation in field instead of removing the breaker from service. Consequently it is desirable to have portable test equipment which can be easily carried to the field to simulate desired AC field signal.
US Pat no 4814712 describes a test kit which simulates over current condition and verifies breaker response. United States Patent 4105965 claims simulation of over current and ground fault test signals. U.S. Pat. Nos. 4,423,459; 4,347,541 and 4,442,472 each discloses variations of analogue and digital implementation of both over current pickup and time delay.
Hence there is a need to design a test kit which can simulate AC three phase test signals to verify the response of the electronic release of breaker over protections like over current, short circuit, directional short circuit, under current, current unbalance, voltage unbalance, instantaneous, under voltage, over voltage, earth fault. There is further need to enhance the scope of release verification over a wide range of protection. There is a further need to provide simulation of test condition for checking release response over harmonic distortion as well as frequency variance.
C) OBJECT OF THE INVENTION:
1) The primary object of the present invention is to a portable electronic testing device which simulates three phase AC real time field waveforms and verifies response of electronic circuit breakers.

2) Another object of the present invention is to design a test kit which can simulate AC three phase test signals to verify the response of the electronic release of breaker over protections like over current, short circuit, directional short circuit, under current, current unbalance, voltage unbalance, instantaneous, under voltage, over voltage, earth fault.
D) SUMMARY OF THE INVENTION
This invention equips engineers with an electronic portable testing device which simulates field condition and verifies the response characteristics of breaker over a wide range of protection functions. Real time field signals can be of any arbitrary shape as it encounters many noises like surges, fast transients, glitches etc. The new generation test kit (NGTK) is capable of simulating accurate replica of such arbitrary three phase AC field signal to check the breaker response. Previous test sets have limitation of simulating any test condition for harmonic testing but NGTK generates waveforms with harmonic contents to test breaker performance over Total Harmonic Distortion.
New generation test kit is implemented to inject the fault simulating signal to the secondary circuit of breaker phase current transformer or Rogowski output. This signal directly feeds to the signal controlling circuit of the electronic release. To implement this test kit the breaker needs to be brought into maintenance mode. At this mode test kit supplies 24 Volt to power up the release and trip unit. User can select the test parameters through any of the following options - test kit keys, in-built test scripts.


Test kit shares test results with remote PC through serial communication. It enables user to monitor test results even being far from the field.
Test Kit Input / Output Connection
Test kit provides six test connecters which include three phase current and three phase voltage connecters. These test connecters are connected to the input of the NGR release at test kit port. Fig l shows the connection between test kit and release. Test parameters can be entered through keys or through PC. This is also described in Figl.

System Description
Field Signal Simulation:
The main purpose of this invention is to generate AC field waveform which may be of
any arbitrary shape.

1. Test kit can simulate AC field waveform. Field signals can be of any arbitrary shape. The field signal is captured in any on line storage device which supports windows file system. Test kit has a provision of external flash card interface. It generates the replica of the waveform as captured from the field.



2. Test kit simulates signals influenced with surge, glitches, spikes and other field noises.

3. Six Test signals include three phase AC current signals and three phase AC voltage signals.
4. New Generation Test Kit also generates harmonic waveforms.


Real Field Error Pattern Simulation:
Circuit breakers are used to protect circuits from electrical hazards. When a breaker is
connected to an electrical distributed network the fault type may follow any of the
following patterns:
i. Power supply was normal previously, after some duration it shoots up for a small
period (in msec or second) and then again comes to the normal condition. Test kit
provides programmable ramp-up time to generate waveform with one amplitude
for selected period and then with another amplitude for a selected period.

ii. Power supply was normal previously, at some duration it reaches the fault condition and continues with that fault for a long duration.


iii. Power supply may continue with some periodic error.

iv. At power on it consumes very high current and after some period it comes to normal condition. This condition may be observed when motors are connected to the network as at start up it consumes high current.


v. At power on only, some fault occurs and power supply is above the fault
threshold, vi. Waveforms with harmonic contents.

Test kit simulates all these type of distorted signal patterns to test the breaker response with real field test environment.
Remote Configuration
Test kit can be configured remotely for giving commands for simulating test conditions through PC. Remote communication enables test kit to provide following features: i. Edit testing parameters.

ii. Access test records. This helps to test and monitor the health of the breaker placed in field from remote station.
Automated Breaker Testing
Test kit leads towards testing automation for breaker. User can select test cases to be performed and choose automatic testing. It simulates the test conditions and logs the test results in standard Windows file.
In-built Test Cases
In-built standard test cases are provided to reduce system testing time. In normal maintenance phase user can select these test cases to check breaker health.

To,
The Controller of Patents,
The Patent office,
At Mumbai


E) ABSTRACT
New generation test kit simulates real time AC field signal and determines the operability of the circuit breakers. It simulates test conditions for standard protection functions like Thermal Overload, Short circuit, Instantaneous, Current unbalance, Voltage unbalance, Under Voltage, Over Voltage, Earth fault etc. Additionally it simulates waveforms with harmonic contents to check breaker performance over total harmonic distortion. It provides three phase AC voltage and three phase AC current signals for testing. All test parameters (like voltage and current Amplitude, Frequency, Phase Shift, Ramp-up time & Amplitude etc) are programmable. User can configure these test parameters manually by entering values through keyboard or remotely through PC based application. It supports in-built test scripts to save the time required to enter test parameters manually and thus accelerates system testing. NGTK also calibrates electronic releases of breakers as it simulates output of the sensor like Rogowski and CT. It provides 24V power supply to power up electronic release to be tested