FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
PROVISIONAL SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
An interface device and a method for tan delta and capacitance measurements
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli
Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR
Shirke Kishor Shantaram, S1 Division, Switchgear Complex, Crompton Greaves Ltd, A-3 MIDC, Ambad, Nasik - 422 010, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention:

Field of invention
The invention relates to an interface device and to a method for tan delta and capacitance measurements of capacitor(s) in a low voltage electrical circuit.
Background
Tan delta and capacitance are two major parameters that provide a measure of the health of a capacitor. Conventionally, tan delta and capacitance measurements of capacitor(s) in a low voltage circuit of an electrical equipment are carried out by using a test device directly connected to the electrical equipment. The various configurations used for testing would, however, require connections and disconnections to be frequently made in the various terminals in the equipment as well as in the terminals of the test device. Such connections disconnections during testing need to be reset to the original setting existed before testing so as to ensure smooth functioning of the equipment post testing. Moreover, such connecting and disconnecting operations would render the testing rather laborious and could also result in damages to the equipment if the capacitor connections are not properly reset after testing.
There is a need for a device arrangement for testing capacitors in a low voltage circuit without encountering the above mentioned problems.


Detailed description
Accordingly, the invention provides an interface device and a method for measuring capacitance and tan delta of a capacitor in a low voltage circuit of an electrical equipment.
In one embodiment the invention provides an interface device for a test device used for tan delta and capacitance measurement of a capacitor in a low voltage circuit of an electrical equipment, the interface device comprising a first set of terminals connected to the equipment's circuitry and a second set of terminals being preset with switch positions that enable the desired configurations for testing.
In another embodiment, the invention provides an interface device for a test device used for tan delta and capacitance measurement of a capacitor in a low voltage circuit of an electrical equipment, the interface device comprising a first set of terminals connected to the equipment's circuitry and a second set of terminals being preset with switch positions that enable the desired configurations for testing, the equipment being a high voltage transformer
In another embodiment the invention provides a method for measuring tan delta and capacitance of a capacitor in a low voltage circuit of an electrical equipment, the method comprising conducting measurements using an interface device comprising a first set of terminals connected to the equipment and a second set of terminals available for the test


device, the second set of terminals being preset with switch positions that enable the desired configurations for testing.
The measurement of capacitance and tangent delta at various configurations using the interface device of the invention is carried out by connecting the equipment terminals to the terminals of the test device, suitably grounding the terminals. The measured values of capacitance and tangent delta obtained are compared with the rated values. If the measured values fall within the prescribed range, the capacitors are continued to be used and if marked deviation is observed from the prescribed range, decision for replacement or repair of the capacitor(s) is made.
The interface device of the invention is preset with switch positions for desired configuration of testing. The device enables faster onsite testing of the capacitors in the transformer. Also the usage of the device minimizes the power system downtime caused due to off-line testing. Further, the interface device eliminates the inconvenience of physically connecting and disconnecting during the testing operation. Consequently, the testing becomes faster and user-friendly.
The interface device can be used to switch among the desired configurations in any low voltage circuit. Advantageously, the interface device is used to switch among the desired configurations in a low voltage circuit of a high voltage transformer. The interface device provides a fool proof interface mechanism by which all the monitoring tests are completed ensuring that once the tests are completed the test device and the equipment


are reset to the original setting. By having the interface device, the complexities of connections at the user end for testing the capacitor(s)/equipment is eliminated. Therefore, the interface device renders user friendly testing of the capacitor parameters and ensures fool proof functioning of the electric equipment.