Servicing Of Transformer, Overhauling, Repairing Of Transformer

Services

Royal Transformers is not only involved in the manufacturing but also plays a major role in the servicing of transformers and we do complete repairing for a variety of different components. We offer a range of services pertaining to On Line Oil Filtration of Transformer, overhauling of power and distribution transformer at site and repairing of Transformer. Our repairing services include repairing of 11kv class, 22kv class, 33kv class, 66kv class and 132kv class transformer where we also have installed a high vacuum double stage transformer oil filtration plant of 6500 LPH Capacity.

WE DO HAVE A HIGH VACUUM DOUBLE STAGE TRANSFORMER OIL FILTRATION PLANT OF 6500 LPH CAPACITY

COMPONENTS OF THE PLANT

It will generally consist of:

1.	Preliminary Filter with Magnetic Strainer	18.	Oil Sampling Valve
2.	Oil inlet Gear pump	19.	Oil Flow Control valves
3.	Heater Tank	20.	Flow switch
4.	Ionic Reaction Column (50 Kg)	21.	Airing valve
5.	Pre Filter	22.	Pressure Relief Valve
6.	Filter Chamber with Micro Filter.	23.	Non-Return Valve
7.	Two Stage Degassing Chamber with Rasching Rings	24.	Digital Temperature Controller
8.	Discharge Pump	25.	Safety Thermostat
9.	Trap- 3 Nos.	26.	Sight Glasses with illuminating Lamp- 2 Nos. in degassing chamber.
10.	Vacuum Pump-2 Nos.	27.	Drain valves
11.	Roots Pump	28.	Vacuum Valve
12.	High Level Float Switch	29.	Oil Inlet & Outlet Valve with solenoid Valves
13.	Low Level Float Switch	30.	Flow Indicator & Pressure Indicator (Gauge)
14.	Temperature Gauge	31.	Electric Control Panel with power coating
15.	Vacuum Gauge	32.	Mimic Diagram
16.	Pressure Gauge	33	Audio Annunciation
17.	Compound Gauge

ULTRA HIGH VACUUM TYPE OIL PURIFYING EQUIPMENT AND FILTRATION PLANT OF 6500 LPH

The Ultra High Vacuum type Oil Treatment Plant is perfect for oil leakage attending of power transformer and reconditioning of used oil in EHV class power transformer, shunt Reactor and other oiled filled equipments. The process followed is quite simple where the oil is heated first and then passed through the specially designed filter and then the oil is vacuum treated, which will further dehydrate and degasify the oil to meet specific specifications:

Parameters	Before Conditioning	After Conditioning
Removal of Moisture	100 PPM	3 PPM
Removal of dissolved Gases	10% by vol.	0.1% by vol.
Break down voltage	20 KV	70 KV
Vacuum level of degassing	-	0.1 mbar
Chamber	-	-
Filtering capacity	Many micron	1 Micron

The transformer power plant has been developed to meet the IS-6034 1989 standards with the most recent modification or revision. In order to achieve the desired results, the plant is designed to offer high vacuum and low temperature of oil. The plant is designed to feature independent pumping system that can also be used to help in degassing chamber. The plant is equipped with control and indication panel that comes with full automation and is made completely weather proof to ensure that servicing of transformer is safe in outdoor use too. In order to ensure successful servicing of transformer, we have made sure that the components have the desired strength and rigidity to withstand various conditions of handling transport. While repairing we will make sure that the components do not have any edges or corners to prevent any kind of injury during usage.

THE PLANT IS CONSISTING OF THE FOLLOWING:-

INLET PUMP :

While attending to the repairing, electrically driven positive displacement gears pump of 6500 LPH capacity will be provided. The pump will be fully tested for vacuum and is ideal for continuous trouble free operation during the complete overhauling process. The pump provided with automatic protection against over pressure.

Interlock arrangement will be provided in the oil inlet pump and the heater to minimize oil leakage and energy loss, unless the inlet pump is on, heaters cannot be energized. Interlocking arrangement will be provided in the Filter Plant between the Inlet Pump and High Level float switch, to avoid excessive rise of oil in the Degassing chamber. The suction head of the inlet feed pump at atmospheric condition at inlet will be of 5 meters.

MAGNETIC STRAINER PRELIMINARY FILTER :
The servicing of transformer also includes the procedure of magnetic strainer that is provided to prevent any kind of damage to the inlet pump. It has the capacity of retaining all particles above 0.5 mm size and all magnetic particles. Thereby the incoming oil will pass through this filter and prevent oil leakage. The strainer provided can be cleaned without dismantling the filter from the pipeline.

HEATERS :

Heaters will be provided during the servicing of transformers to protect tubes in order to avoid overheating, hot spot and breaking of oil. Heaters will be capable of heating oil from ambient temperature to 800 C. for deriving good results, temperature during degassing and dehydration will be maintained within 60 degrees C. Heaters shall be of indirect type and specific heat load must not exceed 2.0 watt/cm2.

Heaters will be interlocked with gear pump and will not be on position unless the inlet pump is working. Heater tank will be thermally insulated to minimize loss of heat by a glass wool.

An additional pre-set tamper proof safety thermostat will be provided to take care of any accidental rise in temperature of oil and the heaters will be put off in such conditions with audio alarm to take care of accident overheating. The thermostat will be set at slightly higher temperature than that of controlling thermostat.

The heater vessel is efficiently designed with baffles to make the oil pass over the entire length of the heater tubes and avoid any chance of localize heating of oil.

One suitable pressure relief valve will be fixed on the heater chamber to prevent any pressure rise above the acceptable limit. Replacement of heating elements will be done without draining of oil. 2 (two) dial type temperature gauges at inlet and outlet of heaters will be provided. A drain valve for heater tank should be provided.

EACH HEATER KW = 2.8 KW. TOTAL HEATER KW = 84 KW. TOTAL HEATER NOS. = 30 NOS.

PRE FILTER :
The filter required in the process of servicing of transformers consists of filter cartridge and it will be suitable for removal of particles above 10-micron size. The unit will be provided with vent and drain valves, pressure gauge at inlet and outlet and other necessary accessories. Necessary bypass system will be provided with valve.

DEGASSING CHAMBER - TWO STAGES :
The Degassing Chamber is a welded M. S. Construction provided with the twin objective of removing dissolved gases and moisture content from the oil. It will be of M. S. welded construction. The chamber will be capable of withstanding the vacuum to which it is subjected. The rasching rings provided will be sufficient to form a thin film of oil and will facilitate easy removal of dissolved gases and moisture at the rated flow of oil. A sight glass with illuminating lamp will be provided for observation of oil flow. One float switch on the degassing chamber will be provided for preventing excess rise of level. It will be interlocked with the inlet pump electrically. Another float switch to control low level of the oil in the in degassing chamber will be provided and it will be electrically interlock with discharge pump. There is an air valve in the degassing chamber for reducing the vacuum in the system in the event of excessive foaming in the oil.

IONIC REACTION COLUNM (Deoxidizing Column) :

The Ionic reaction column is provided to fulfill the objective of eliminating moisture content from the oil. The Chamber will be capable of withstanding the vacuum. The chamber is provided with a sufficient volume of activated alumna to abstract the maximum moisture content at the rated flow of oil. Necessary bypass system will be provided (by valve) along with aeration and drain valve.

VACUUM PUMPING SYSTEM :

The plant will be provided with suitable vacuum pumping system which will be capable of creating High Vacuum, which is required to remove the moisture content and gas content from the oil. This is driven by 3 phase, 440 V, only 50Hz, Electric Motor. In the first stage we will provide Rotary oil sealed vane type specially designed for High Vacuum pumping applications in degassing Chamber.

Vacuum Pump - I

Free air Displacement	1000LPM
Ultimate Vacuum	0.05 mm of Hg.
Make	Indo Woo Sung

Vacuum Pump - II (Additional)

Free air Displacement	1000LPM
Ultimate Vacuum	0.05 mm of Hg.
Make	Indo Woo Sung

MECHANICAL BOOSTER PUMP (ROOTS PUMP) :

In the second stage of servicing of transformer, roots pump will be provided which offers high suction capacity. Two identically cocoon shaped rotors continues rotating while maintaining certain small clearance with the casing and thereby exhausting the water vapor, dissolved gases & moisture withdrawn from the de-gassing chamber to the backing pump. This particular machine also features built in facilities of air compressor for painting and leakage testing to help in the servicing of transformer. The booster pump (roots pump) operated in combination with rotary vacuum pump will give better performance to get vacuum pressure with minimum of consumption. This will be driven by 3 phase 440 volts only 50 Hz. Electric Motor as per IS Standard.

Capacity : 430Μ3 / hr.
Make : Kinney (Imported)

MICRO FILTER & AIR COMPRESSOR :

Cartridge filters of 1 micron rating will be provided. This cartridge element will have large dust holding capacity and suitable for transformer oil in service, sub-micron filteration and the media will be hygroscopic. The replacement of cartridge is quite easy and can be done without any special tools. The filter body will be fabricated of mild steel and designed for leak tightness at full vacuum and high pressure. The Compound gauge will be provided in the filter vessel for inlet pressure in order to ascertain condition of cartridge elements. Aeration will be provided on the filter vessel, for aeration during draining. Necessary bypass system will be provided with valve.

The machine has also in built facilities of air compressor for painting and leakage testing.

OIL EXTRACTION PUMP (DISCHARGE PUMP) :

A centrifugal discharge pump suitable for sucking oil from Degassing chamber held under vacuum is provided during the servicing of transformer. This is fully tested for pressure and vacuum leakage. If the level of oil in the degassing chamber decreases then the required level, then it should be controlled with the outlet pump by pass valve. The oil discharge pump will be located at a suitable level below the degassing chamber so as to ensure adequate suction head for the pump.

Non-return valve in order to stop reverse flow of the oil in case of power failure, the pumping system will preferably by self priming type safety interlock to protect pump against dry running will be provided.

HOSES FOR TRANSFORMER OIL, VACUUM, AIR AND WATER :

Sr.No.	Description	Qty.
1.	Rubber Hoses for Oil Suction Size 1 ½”	15 Meters.
2.	Rubber Hoses for Oil Discharge Size 1 ½”	15 Meters.

Separate reinforced rubber hoses will be each of 15 Mtrs. length complete with connecting flange for each operation i.e. oil suction, oil discharge.

Hose pipe for oil service will suitable for transformer oil application and will withstand temperature upto 800C, and pressure up to 2.5 Kg/CM2. Inlet and outlet nozzle of purification plant and corresponding hoses will be of 40NB.

INSTRUMENTS :

Following instruments will be provided on the Filtration Plant.

1.	On line PPM Measurement Instrument.
2.	Compound Gauge at filter outlet.
3.	Pressure gauge at de-gasifier.
4.	Vacuum Gauge in between roots vacuum pump and rotary vane vacuum pump.
5.	Vacuum indicators at degasser.
6.	Sight glass in degasify.
7.	Temperature indicator cum controller at heater outlet.
8.	Voltmeter.
9.	Ammeter.
10.	Compound Gauge at filter Inlet.

CONTROL PANEL :

All electrical control gear, mains isolating arrangement, starters, contactors, pilot lamp, push buttons, HRC fuses, relays, indicating lamps and interlocking will be housed in a compact control panel and made of CRCA sheets. A mimic diagram with indication lamps showing on/off status of various equipment will be provided on the control panel. All wiring will be neatly/routed and all wire termination will be suitably identified. For illumination, a bulb will be provided. The surface of the panel should be power coated. You have to provide suitable DOL starter along with the over load relay, MCB, Indicating Lamp & push Button for our 5 HP compressor motor supply. The compressor will be provided by us. You are requested to give one 3 Phase point and 2 single phase 15 Amps. Points outside the panel for our requirement with suitable rating MCB. We will provide 1 No. 250 VA. 440/220 V. transformer for power supply control and illumination purpose as requested by you. You are requested to approve the wiring diagram prior to start the work. All the cables and wires like heater chamber, inlet/outlet pumps, vacuum pumps etc. are of copper made and current density should not more than 1.5 Amps per mm². The same will be thoroughly checked at the time of our final inspection at your works.

AUDIO ANNUNCIATION :

1.	High Oil Temperature	5.	Roots Pump motor trip.
2.	Inlet pump motor trip	6.	Low oil level in degassing chamber
3.	Outlet pump motor trip	7.	High Oil Level in degassing chamber.
4.	Vacuum Pump motor trip

All controls and annunciation equipment will be suitable for 240 V A.

Suitable interlock as described against each equipment will be provided for safe and trouble free operation.

ELECTRICAL SYSTEM :

The plant will receive 415 V (±10%), 3-phase, 50 Hz, 4 wire power supply through flexible cable in the distribution panel located on the plant. The incoming of the distribution panel will be switch fuse unit. Provision for earthing the plant at the operating locations with earthing terminals for safety will be provided. The plant will be suitable illuminated and ventilated for comfort of operator.

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