FIELD OF THE INVENTION
This invention is concerned with the proper impregnation of magnetic coils using
proper pressure measurement by creating respective vacuum.
BACKGROUND OF THE INVENTION
Magnetic Coils such as chokes and transformer are essential part of various
electronics modules related to flow of electromagnetic power and conversion of various
sinusoidal voltages. Proper impregnation of said coils is one of the important aspects
which are crucial during manufacturing process of coils. Normally, in conventional
method, coils were varnished by dip-method but as soon as the number of wire-turns
increases, this method is not much supportive. By doing proper impregnation, varnish
flows properly up-to the inner most layer of the coil and utmost insulation can be
obtained.
SUMMARY OF PRESENT INVENTION
Present invention is concerned with the impregnation process of the magnetic
coils which are widely used in different industries.
In accordance with one aspect of the present invention is to provide a simple
system for coil impregnation which consists of blocks made by easily available
resources.
In accordance with another aspect of the present invention is to provide proper
insulation for achieving requisite output voltage in terminals of said magnetic coil.
Annexure‐II
In accordance with another aspect of the present invention is easy to operate,
repair and maintained the said vacuum impregnation system without help of trained
persons.
Main objective of this methodology is to provide smooth insulation and proper
varnishing at the bottom most layer of the coil.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the present invention will become more apparent and
descriptive in the description when considered together with figures/flowcharts
presented:
Fig. I : Block diagram of Vacuum Impregnation System with varnish in the
pressure chamber
Fig. II : Block diagram of Vacuum Impregnation System without varnish in
the pressure chamber
DETAILED DESCRIPTION
Magnetic coils are basic building blocks of electromechanical modules used in
many industries. Normally said coils are used to carry & propagate electromagnetic
power in the electrical and electronics circuit on the basis of number of turns used in the
magnetic coils. These coils are also used as transformer for voltage transfer in various
ways. During manufacturing of coils, impregnation is one of the important operations
which affect its quality and reliability. Vacuum impregnation is one of the best methods
used for magnetic coil.
Vacuum impregnation system is customized combinations of various chambers,
vacuum pump, pressure line and pirani gauge. This setup is used for impregnation of
magnetic coils with utmost quality and reliability with or without help of pressure
generated by varnish. This system is easy to make, operate and maintained such that
no specialized training is required. This system is very useful for any number of turns of
magnetic coils as required. The set-up is explained in attached figure I & II.
Annexure‐II
The operating procedure of vacuum impregnation is enlisted below:
• After cleaning the dust & the dirt of magnetic coils with compressed air, said coils
are dried in oven at desired temperature for requisite duration. Parallel, the
varnish is prepared to the desired viscosity level. To achieve desired viscosity,
thinner such as toluene or mixture with white sprit is mixed. Before impregnation
of coils, varnish is filtered through multilayer of muslin cloth. In addition to this,
dried coils are loaded in impregnation container set.
Following procedure is followed for carrying out impregnation using this setup:
Procedure (1): Refer: Fig I
I) First, coils (to which are due for impregnation in varnish chamber) are kept in
a small metallic container inside the impregnation chamber.
II) It is strictly mentioned that the valves V1 remain open & V2, V3 remain close
in this condition.
III) Later, pump is switched ‘ON’ & the pump is allowed to operate till desired
vacuum level at ambient temperature. Once the desired level is achieved the
valve V1 is closed & it is allowed the coils to be under vacuum for desired
time.
IV) After this, the air tight lid of pressure chamber is opened & the varnish
(Sufficient Quantity of Varnish should be taken so that all coils are properly
submersed) is poured.
V) Then, the valve V1 is closed while V2, V3 is opened. Now the valve V1 is
opened
VI) Later, the vacuum pump is switched ‘ON’ & the pump is allowed to operate till
desired vacuum level until achievement of ambient temperature. Once
desired vacuum level is achieved, the value V1 is closed (during vacuum
buildup process bubbles may be seen coming out from varnish). Then, the
Vacuum pump is switched off. This activity is to be carried out for desired
duration till the whole air is sucked & Varnish settles down.
VII) Then, the valves V2 & V3 are opened and the pressure is applied through
pressure line, till the desired pressure level is achieved in the impregnation
Annexure‐II
chamber. Once pressure level is maintained (or Varnished is poured out), the
valves V2 & V3 are closed. This activity (pressure buildup) should last for few
seconds.
While using the pressure line, care must be taken that the pressure inside the
chamber is not allowed to buildup for more periods otherwise this may lead to
the leakage/breakage of impregnation chamber.
VIII) Then, the coils are allowed to impregnate for few minute.
IX) After that, the valve RV1 is released to release the air.
X) This operation (IX) to XI) is repeated for carrying out and 2nd cycle of
operation.
XI) Lastly, the coils are taken out from the container & wiped out excess varnish
with filter paper.
XII) Further, the coils (while hanging) are kept in an oven for 3hrs at 80°C for
drying.
XIII) Then, the excess deposition of varnish (by scrapping) is removed from the
coils.
XIV) Then, the coils are kept in an Oven/Thermal Chamber at 120°C for 10Hrs for
drying.
XV) Finally the coils are taken out from oven and cool it to room temperature.
Further visual inspection of Coil is carried out for free surface from inclusion,
unfastened turn, rough leakages and accumulation of varnish.
XVI) It is permissible to clean the leakage of varnish mechanically through brass
scrapper.
Procedure (2): Refer: fig II
I) First, the coils (which are due for impregnation in varnish chamber) are kept
in a small metallic container inside the impregnation chamber and the
required Quantity of Varnish is poured in the container till all the coils are
properly submersed (level of varnish should be 20-30mm above the coils).
II) Then, the valves V3 are closed while V1 is opened.
Annexure‐II
III) Then, the vacuum pump is switched ‘ON’& the pump is allowed to operate till
desired vacuum level is achieved at ambient temperature after maintaining
the level for desired duration.
IV) Once desired vacuum level is achieved, the valves V1 & V2 are closed during
vacuum process bubbles may be seen coming out from varnish. This activity
is carried out till the air is sucked up & the Varnish settles down. After then,
the Vacuum pump is switched off. Then the coils are kept in vacuum condition
for desired duration.
V) Further, the valves V2 & V3 are opened and the pressure is applied through
pressure line, till the desired pressure level is achieved. Then, the value V2 &
V3 are closed. This activity (building of pressure) should last for few seconds.
While using the pressure line care must be taken that the pressure inside the
chamber should not be allowed to buildup for more periods otherwise this
may lead to the leakage/breakage of impregnation chamber.
VI) Later, the coils are allowed to impregnate for few minute.
VII) Then, the valve RV1 is released to release the air.
VIII) After that, operation (VI) to (VIII) for carrying out is repeated till next cycle of
operation.
IX) Then, the coils are taken out from the container & wiped out excess varnish
with filter paper. Then, the coils (while hanging) are kept in oven for requisite
duration at 80°C for drying.
X) Further the excess deposition of varnish (by scrapping) is removed from the
coils.
XI) Finally, the coils in an Oven/Thermal Chamber at 125°C for 10 hrs are kept
for drying.
XII) Then after, the coils are taken out from oven and cooled in the room
temperature.
XIII) Further visual inspection of Coil is carried out for free surface from inclusion,
unfastened turn, rough leakages and accumulation of varnish.
XIV) It is permissible to clean the leakage of varnish mechanically through brass
scrapper.

WE CLAIMS:-
Accordingly, the description of the present invention is to be considered as illustrative only and is for the purpose of teaching those skilled in the art of the best mode of carrying out the invention. The details may be varied substantially without departing from the spirit of the invention, and exclusive use of all modifications which are within the scope of the appended claims is reserved. We Claim

1. A vacuum impregnation system comprises:
- impregnation chamber: for performing impregnation of magnetic coil to achieve proper insulation.
- pressure chamber: for generating requisite pressure for removal of air bubble from the varnished area of the coil
- vacuum pump: for creating vacuum in system during impregnation
- pirani gauge: for pressure measurement for manufacturing of chokes and transformers (coils) used in different units of Aircraft.
2. The vacuum impregnation system of claim 1 wherein, is used as high pressure vacuum impregnation with help of varnish and as detailed using Fig I.
3. The vacuum impregnation system of claim 1 wherein, is also used as high pressure vacuum impregnation without varnish effect and as detailed using Fig II.
4. The vacuum impregnation system of claim 1 wherein, provides varnish up to the bottom most layers for any number of turns of coils.
5. The vacuum impregnation system of claim 1 wherein, provides proper Insulation in coils terminal which helps in obtaining requisite output voltage.
6. The vacuum impregnation system of claim 1 wherein, is used for varnish coating which is independent of number of turns of coils.
7. The vacuum impregnation system of claim 1 wherein, provides uniform varnishing irrespective of location of wire turns of magnetic coils.
8. The vacuum impregnation system of claim 1 wherein, permits removal of extra varnish coat using scrapped material such as brass scrapper. ,TagSPECI:As per Annexure-II