Nach Engineering Private Limited

Insulating Oil Processing plants & equipments for maintenance of power transformers:

For effective maintenance of power transformer in service, maintenance of dielectric properties of insulation, whether, solid or liquid is most important.

We manufacture:

• High Vacuum Insulating Oil Processing Plants with purpose of commissioning & maintenance of all types of transformers.  
• Dehydration plants for rapid & economical transformer drying.

Equipments in the oil processor are:

• Oil Pumps: Positive displacement type gear pumps with accessories for inlet & centrifugal pumps with accessories for discharge side.

• Heating System: Heat exchanger of low heat density, with temperature controlling arrangement & safety appliances.

• Filteration System: Edge filter with cleaning arrangement or through away type cartridge filter & filter press for removal of sludge.

• Degassing System: Sealed chamber with raschig rings for single stage & multi stage operations, equipped with various appliances.

• Vacuum Pumping System: Rotary oil sealed pumps, combination of mechanical booster & rotary pumps with all required components.

• Control Panel: Centralised control panel with mimic diagram instrumentation and all accessories required for plants as per specification.

• Mounting: Plants are available in both stationary & mobile as per requirements.

Optional Features:

• Transformer evacuation system as per requirement.
• Ionic reaction column for acidity correction and facility of additional inhibitors.
• Instrumentation for indication and recording various oil parameters.

Application:

Requirement of working vacuum becomes much higher for treating oil having high acidity & low interfacial tension as compared to theoretical requirements of new oil. To meet this field conditions, high vacuum processing plants with multi stage designed are most effective. For dehydration of these transformers multi stage plants can effectively meet:

• Oil in transformer which is in use, has high acidity and low IFT as compared to new oil, as per IS – 335.
• To enable moisture in paper insulation to migrate in the surrounding oil, it has to be maintained at higher temperature of 70ºC to 80ºC and also to a low dissolved moisture contained level. Single stage plants can achieve results as good as multi stage plants for treating new oils. But it takes longer time for oil in use. Thus improvements in transformer IR values will be slow and limited.

Dehydration equipment for transformer in service & maintenance:

Drying of transformers is a major problem due to:

• More shut down time
• Difficult site conditions
• Process in use at present is uneconomical, lengthy and less effective.
• Insulation requires drying is oil impregnated. Combined effect of heating, moisture, dissolved oxygen & acidity in oil, attacks iron, copper, varnishes, paints, which results in sludge formation. It forms very tiny substance, which adheres to winding insulation, side walls of tank, ventilating ducts & cooling fins. Sludge deposited on insulation causes severe shrinkage of insulation & finally pre mature break down. Water is also produced during aging process accelerated by catalytic action of copper, iron & oxygen.
  

Deals in Single stage Oil Filter machines.

The Need: Generally, hydraulic oil is to be maintained at very high quality of Purification. The Oil often having large sizes of particles is passed through coarse type filter, to trap the large sized particles. Having taken care of micronic and sub-micronic particles, it is further finely cleaned by electro-statically, operated hydraulic oil cleaner & brought to the international standards.

Principle: The oil is pumped and passed through a cleaning cell. An electric field is created in this cell by a high voltage applied in between two electrodes. Oil is then passed through the field. The fine particles are attracted towards positive electrode and are collected on collector papers as sludge, thereby purifying the oil at a higher degree of purification.

Working Conditions: Best performance results of the hydraulic oil are obtained at following conditions:

• Temperature : Less than 60 º C.
• Viscosity : Less than 300 centi. Stokes.
• Moisture : Less than 500 PPM

NEC 50 & NEC 100 purifiers are not suitable for following conditions.

• Oils with moisture more than 500ppm, but additional dehydrator unit can be connected to the system & good performance results are obtained.
• Synthetic Oils.
• Any conductive oil.
• Oil with Detergent dispersants.
  

NEC 50 Specifications:

• Cleaning Tank Capacity : 50ltrs.
• Cleaning rate : 8 to 10 ltrs per min.
• Power Supply : 230 volts, A.C. Single phase 50Hz. with Earth.
  

NEC 100 Specifications:

• Cleaning Tank Capacity : 100ltrs.
• Cleaning rate : 16 to 20 ltrs per min.
• Power Supply : 230 volts, A.C. Single phase 50Hz. with Earth.
  

THE PURIFIERS--NEC50 & NEC100 Benefits:

• No chemical treatment is given, hence no contamination or no change in chemical structure occurs.
• Operation is ‘Round the clock’ as both the machines are continuously rated.
• The unit is easy for installation. Inlet / Outlet hoses are to be connected to the equipment. A power supply connection is to be given.
• For removal of moisture, if oil is more contaminated with moisture, additional dehydrator unit is to be connected to the system to avoid break down of main unit. This enhances system performance.
• This is completely indigenous as no component is imported. Hence no dilemmas regarding import of paper or spares exist.
• Robust HV Transformer design and tripping circuit improve reliability even under rugged working conditions.
  

VACUUM IMPREGNATION PLANTS are generally required in Electrical Industry. Impregnation is most important process to improve Insulation Resistance of the electrical components. In turn it  improves life of the component and hence impregnation has become compulsory to each and every electrical components. Vacuum impregnating plants designed for impregnation with Varnishes, are generally suitable for coils LT/HT Motors. This is the most important process for electrical insulation.

Design of vacuum impregnating plants depends upon following aspects:

• Design, Constructional features, winding details of components to be impregnated.
• Impregnant to be used.
• Class of insulation required
• Operating temperature
• Surrounding Environment
  

Above requirements necessiates a very wide range of impregnating plants. We manufacture all types of vacuum impregnating plants, to meet above requirements. These are suitable for all types of Varnishes, Oils, Epoxy resins Wax, Petroleum Jelly etc.

These have following Sailent features:

• Unheated impregnating vessel.
• Impregnant storage tank.
• Inter-connecting piping, valves.
• Stoving vessel.
• Vacuum pumping system.
• Impregnating vessel pressurising arrangement, with dryer for air/nitrogen.

In order to enable us to design impregnating plants, following information is essential:

• Physical dimensions of charge and No. of components to be impregnated per batch.
• Impregnant system to be used.
• Working vacuum and working pressure for impregnation.
  

                 a) Dipping Method.
                 b) Vacuum Impregnation.
                 c) Trickle or Rotary Impregnation.

a) Dipping Method: The components having low operating voltages, having less temperature rise, less operating cycles, most stable or havinglow electrical stress and having large coolingarea components, generally come in this type of impregnation.

• Process Plant: The plant will consist of  Dipping or  Impregnating Chamber of suitable size and Storage Tank with required accessories such  as stirrer arrangement, water chilling system and /or heating system, insulation, additional pressure  arrangement  for  transfer  of  Impregnant from storage tank to  Impregnating Chamber.

b) Vacuum Impregnation: This method  of Impregnation is most commonly used. Components having  low cooling space, high operating temperatures, continuous duty cycle, lower diameters of winding wires, high electrical stress etc. and combination of above factors, generally use this Vacuum Impregnation method.

• Process Plant: The plant will consist of Vacuum Impregnating Chamber, Vacuum Pumping system, Condenser, and Storage Tank, StChilling system, Heating system, Pressure  system for transfer of Impregnant and  for additional penetration of impregnant.
  

c) Trickle Impregnation: This method is generally used for quick production cycle and individual impregnation of components. Generally  resins are impregnated with this system and for most components heat is generated  by  heating  individual  component.

• Process plant: The plant will consist of  individual and continuous operating system with arrangement for continuous rotating of individual or group of components or component station. Metering of impregnant, pre heating of component by suitable method such as D.C. resistance heating etc.