FIEED OF THE INVENTION:

The present invention generally relates to regenerating breathers used in electrical devices. More particularly, the present invention relates to a time-based, automatic self-regenerating breather for providing dehumidified air to a transformer.

BACKGROUND:

Oil is used as an insulating medium and coolant in electrical devices, such as power transformers, power chokes, on-load tap-changers etc. Transformers play an important role in power systems. Various loads are connected to the power system and the fluctuation in the load influences the performance of the components in the power system. So, the load on the transformer does not always remain constant. The increase / decrease in the load on transformer, results in change of pressure inside the conservator tank of the transformer. The insulating oil in the conservator tank heats up and expands when there is full load on the transformer. This results in the expulsion of air and oil from the transformer. Similarly, the insulating oil in the conservator tank cools down and contracts when there is no load on transformer. This results in drawing air from atmosphere into the transformer. This entire process is called breathing and this process is facilitated by breathers. Breathing process is performed in a transformer to let the flow of air in and out through the breather.

The breather typically includes a desiccant material such as silica gel to absorb the moisture present in the air that enters in / expels out from the transformer. This largely prevents any reduction in dielectric strength of the insulating oil and also prevents the formation of condensation in the conservator tank. The silica gel is initially blue and turns pink after absorbing moisture. Hence, these breathers are regularly monitored and are replaced manually. This has led to the development of regenerating breather system that prevents the replacement of silica gel manually and the system uses regenerative agents or any moisture absorption means to absorb moisture present in the air.

Regenerating breather systems are well known in the existing art.

For example, United States Patent Number 7332015 to Thomas M. Golner et.al, entitled “Automatic dehydrating breather apparatus and method” relates to an automatic dehydrating breather apparatus for removing moisture from air. The apparatus consists of two humidity sensors for measuring the level of humidity in tank and in the breather. Based on the reading from both the sensors, the control unit initiates a purging cycle to heat the heating element present in the breather. The generation of control signal actuates the valves present in the air flow passage to prevent the back flow of moisture and exhaling moisture. After completion of exhaling process, the valves are positioned back to normal. The purging cycle of the apparatus is time based and is adjustable based on the fluctuation of moisture detected.

PCT Publication Number W02017002128 to Balkrishna Potnis Shrikant entitled “Regenerating breathers system” describes a system to dehydrate the air entering the oil tank. The system includes first and second breathers and corresponding desiccator tanks with plurality of valves that are controlled by a control unit. The function of the first breather is to dehydrate the moisture entering the oil tank. Once the absorbent of first breather absorbs moisture to its full capacity, the second breather starts functioning. The moisture absorbed by the absorbent during regeneration process is sucked using ventilation fan and is released out without allowing any condensation in the breather. The dehydration of air and removal of moisture is performed by both the breathers at the same time.

Patent and Publication Numbers CN204463993, CN104575963 and CN104517706 deals with breathing apparatus for dehydration of moisture using silica gel breather. The apparatus is set with predefined threshold value and microwave heating is performed for the removal of moisture from the absorbent. The withdrawing of moisture from silica gel ends as the gel changes its colour from blue to pink. Though there are various breather systems for performing regeneration based on set threshold value, none of them are time specific during regeneration process. Also, most of the systems stop the regenerating operation depending on the change in colour of silica gel.

Hence, there is a need for a method and system that operates on the principle of time based regeneration and controls all the electrical elements to continuously monitor the humidity level in the regenerative breather system in a cyclic manner and to reduce the humidity level therein.

OBJECTS OF THE INVENTION:

The primary object of the present invention is to provide a time based, automatic self-regenerating breather system and method to monitor the humidity level in a desiccant.

Another object of the present invention is to control the electrical elements of the system in three states with respect to time.

SUMMARY:

The present invention discloses an automatic self-regeneration system and method for controlling and reducing the humidity level in desiccant chamber of a breather in electrical devices such as transformer.

According to the present invention, the automatic self-regenerating breather system comprises a desiccant chamber inside a breather, a humidity sensor, a heater, a fan, a control panel including a microcontroller and a timer, solenoid valves, a view glass and LEDs to indicate the ON / OFF state of electrical elements and status of the breather. The heater, fan and the solenoid valves form the electrical elements of the system. In accordance with the present invention, the automatic self-regenerating breather operates on the principle of time - based regeneration where the regeneration begins when the humidity in the desiccant chamber reaches a predetermined threshold (hereinafter referred to as “set value”). Once the regeneration begins, the heater and fan run for some time after which the heater is switched OFF and only fan runs for certain time. Once the heat inside the desiccant chamber subsides, the main valve connecting the desiccant chamber is opened to allow the transformer to breathe in/out. The cycle starts again till the humidity value reaches below the set value.

In the present invention, humidity level in the desiccant chamber is controlled by humidity sensor and microcontroller and thereby activates / controls all electrical elements in various states of time period like regeneration time, cooling time and breathing time.

The objective and advantages of the present invention will become more evident from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

The objective of the present invention will now be described in more detail with reference to the accompanying drawings, in which:

FIG. 1 shows the automatic self-regenerating breather according to present invention;

FIG. 2 shows the automatic self-regenerating breather with the electrical elements of the system; and

FIG. 3 shows a flow chart indicating the method proposed in the present invention. REFERENCE NUMERALS:

1: Breather 2: Humidity sensor 3: Control panel 4: View glass 5: Status LED indicators 6a: Fan

6b: Pipe connecting solenoid valve and conservator 6c: Solenoid valves

6d: Bellow hose connecting desiccant chamber to solenoid valve 6e: Heater

OFT ATT /FT) DESCRIPTION OF THE INVENTION:

The present invention proposes a system and method for automatic time-based self-regeneration for controlling and reducing the humidity level in desiccant chamber of a breather in electrical devices such as transformer.

Referring to FIG. 1 , according to the present invention, the system comprises a desiccant chamber (not shown) inside a breather (1), a humidity sensor (2), a heater (6e), a fan (6a), a control panel (3) including microcontroller and a timer, solenoid valves (6c), a view glass (4) that allows the user to see a portion of silica gel filled inside the chamber and FEDs (5) to indicate the ON / OFF state of electrical elements and status of the breather (1). In FIG. 1, the door of the self-regenerating breather is in closed state.

In the present invention, the heater (6e), fan (6a) and solenoid valves (6c) are electrical elements of the system as shown in FIG. 2 in which the door of the self-regenerating breather is in open state. The solenoid valves (6c) perform the valve opening and closing functions. The solenoid valve (6c) is connected to the conservator through pipe connection (6b) at one end and the other end of the solenoid valve (6c) is connected to the desiccant chamber by means of a bellow hose (6d). The solenoid valve performing normally open and normally close operation is preferably a single valve assembly where 3/2 solenoid valve is used, in which the normally open and normally closed valve functions are clubbed together.

The overall operation of the regenerative breather shown in FIG. 1 is explained below:

In accordance with present invention, the automatic self-regenerating breather (1) operates on the principle of time-based regeneration where the regeneration begins when the humidity in the desiccant chamber reaches a predetermined threshold (hereinafter referred to as “set value”). Once the regeneration begins, the heater (6e) and the fan (6a) run for some time after which the heater (6e) is switched OFF and only fan (6a) runs for certain time. Once the heat inside the desiccant chamber subsides, the main valve connecting the desiccant chamber is opened to allow the transformer to breathe in/out. The cycle starts again till the humidity value reaches below a set value.

In a preferred embodiment of the present invention, the method of operation of the automatic self regenerating breather (1) is provided.

Whenever humidity sensor (2) senses humidity level “at or more than” the desired set level (this condition is referred as “worst case scenario”), the humidity sensor (2) gives its input to micro controller. The micro controller gives its command to activate all electrical elements in the system thereby switching ON the heater (6e) and the fan (6a). The normally open solenoid valve in the system becomes normally closed and normally closed solenoid valve becomes normally open at this condition as shown in flow diagram / flow chart FIG. 3. The electrical elements remain activated for a particular set time called ‘Regeneration Time’ (Tl). For example, the regeneration time Tl is about 2 hours. Humidity level in the desiccant, preferably silica gel starts decreasing when the electrical elements are in activated state / energized state.

After the regeneration cycle, the microcontroller in the control panel (3) turns off the heater (6e) and the fan (6a) continuously functions to remove the heat present in the chamber. The normally open solenoid valve is in closed position and the normally closed solenoid valve is in open position. This cycle is performed for a certain time period T2 which is referred as the ‘cooling time’. For example, the cooling time T2 is about 15 minutes.

After the cooling time, the heater (6e) and the fan (6a) of the breather (1) are turned off and the normally open solenoid valve i.e. the main valve is opened and the normally closed solenoid valve is closed thereby rendering the elements of the system in denergized state of the system. This allows the transformer to breathe in/out. This state is maintained for a particular time period T3 which is termed as ‘breathing time’. For example, the breathing time T3 is about 15 minutes.

After achieving the breathing time, the system continues the cycle by energizing the elements again till the humidity value in the desiccant chamber reaches best case value. Therefore, as the time progresses, humidity level sensed by the humidity sensor (2) reaches a desired level (this condition is referred as “Best Case Scenario”) to switch off the energization of all the electrical elements.

Thus, the system is useful for removing the moisture in silica gel, thereby avoids replacement of desiccant chamber manually.

While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.