Treatment on-line of the transformers

	The standard plants ARRAS MAXEI are enriched today with a version for the treatment on-line of the transformers. Totally secured and validated in test platform manufacturer, our oil treatment plants on-line enable the treatment in complete security of your transformers. Type of transformers treated till 220 kV Quantity of oil maxi advised 40 000 liters The oil treatment plants on-line ARRAS MAXEI are studied to enable the treatment of a running transformer. The main interest is based on the treatment without transformer’s stopping. So, there is no transformer’s standstill if the connection to the treatment plant can be realized on-line (security distance between the connections transformer and the terminals). They are designed to treat a dielectric oil having, before treatment, a moisture content of about 50 ppm and in dissolved gases of approx. 10% by volume. After getting the optimal treatment conditions, the oil will go out after one pass at a temperature of 70°C maximum with moisture content under 5 ppm* and dissolved gases approx. 0,1% by volume*. The breakdown voltage of the oil will be higher than 75 kV after treatment. For an oil at 20ppm, this one will go out after one pass at about 3 ppm*. These characteristics are given for an oil having a distillation curve of 1.10-2 mbar at 80° C. For a treatment of the transformer’s active parts, these data can vary in function to the transformer’s state.

Main characteristics Nominal flow rate** during treatment in l/h 4000 Heating power in kW 78 Total power in kW 88 Filtration* per cartridge in µm nominal 0,5 Ultimate vacuum against closed suction in mbars 0,08 Vacuum during treatment in mbars 0,5 to 2 ** Approx. values. * Consumable cartridges with filtration expressed in µm absolute. All our plants are equipped in standard with tropicalized electrical material, for a supply tension 400 Volts 3 phases 50 Hz and auxiliary of control in 220 Volts per transformer.

The plus points of the treatment on-line ARRAS MAXEI:

Components of the plant
- 1 Inlet oil group motor-pump.
- 1 Direct electrical heating group.
- 1 Filtration group 0,5µ nominal.
- 1 System of on-line measuring of moisture content.
- 1 Dehydration cell.
- 1 Outlet oil group motor-pump under vacuum.
- 1 Free gases catching group.
- 1 Filtration group 1µ absolute.
- 1 Single-staged vacuum group motor-pump.
- 1 Set of devices for measuring, controlling, alarming, regulating.
- 1 Control panel.
- 1 Set of flexible hoses, valves and accessories for the connection of the plant to the transformer.
The standard plant is installed on a platform in metal section iron with retention tray and maintenance wheels.

Control panel.
The oil treatment plants on-line ARRAS MAXEI are equipped with a waterproof panel industrial type in painted steel, with automate, contactors, relays, fuses, terminal boards and cables necessary to the running of the plant, and on the door, the operating desk, the temperature display, les light switches and alarming lights of the different elements.

The plus points of the treatment on-line ARRAS MAXEI:

• Continuous control of the inlet oil temperature before degasing (regulation PID) and of the outlet oil temperature.
  
  
• Controlling of the overheating through security thermostat
  
  
• Running of the plant by operating desk
  
  
• Permanent control of overpressures in the net, by pressostats, security valve and by pass.
  
  
• Visualization of the inlet flows before degasing (regulation and flow mini) and of outlet flows.
  
  
• Continuous control of the oil levels and of condensers in the plant
  
  
• Automatic regulation of foaming effects
  
  
• Tri filtration by strainer (0,8mm), double filtration before degasing (2 filters 1µm nominal) and fine filtration (0,5µm nominal) at outlet.
  
  
• Clogging control of the filters by pressostats
  
  
• Vacuum control by Pirani gauge and manometer
  
  
• Removal of free gases and air bubles at plant outlet
  
  
• Detection and automatic draining of free gases at plant outlet
  
  
• Continuous measurement of moisture content (% water)
  
  
• Numeric recording of treatment parameters
  
  
• Vacuum accumulator for draining of the transformer’s connections.
  
  
• Self compressed air by compressor.
  
  
• Secured connections to the transformer
  

Automated and rationalized starting sequences.
Filling of the plant.
Putting under vacuum of the piping.
Filling of the piping.
Treatment in closed circuit.
Treatment on transformer.
Draining of the piping.
Draining of the plant.