Oil Purification System

ELECTROMONTAJ S.A. EXPERIENCE IN THE FIELD OF MOUNTING, OIL FILLING, RECONDITIONING AND REGENERATION OF THE TRANSFORMERS INSULATION

 

SC Electromontaj S.A. has installed over 140 transformers and autotransformers 220kV, 400kV and 750kV, over 2000 110kV in high voltage power stations both in Romania and in other countries.

In recent years S.C. Electromontaj S.A. has been involved in the refurbishment of the 110 ÷ 400kV transformer stations with the replacement of the transformers or with the modernization and revitalization of the transformer insulation.

In Romania over 2500 transformers and high voltage autotransformers are in operation, out of which over 80% have more than 25 years of operation. Given that the standard life is 30 years, the financial effort to replace them would be huge. Therefore, as is known and practiced worldwide, it is preferable to revitalize them and prolong their life span (where it is possible after a careful diagnosis).

SC Electromontaj S.A. has got a modern installation for heating, degassing, oil filtration and regeneration of the paper-oil complex, manufactured in Switzerland (supplier – Micafluid, generation 2012).

Micafluid Oil Purification Plant VOP 060S Unit Val.
Dimensions (optional equipment excluded)
– Length L
– Width B
– Height H
– Weight (all optional equipment included, but without container assembly)
[mm] [mm] [mm] [kg] 2870
1650
2100
2100
Max. recommended oil content of transformer [t] 12-60
Oil throughput:
– oil treatment min.
– oil treatment max.
inlet pressure min. (abs)
inlet pressure max. (abs)
max. feeding pressure at plant outlet (abs)
[l/h]
[l/h]
[bar]
[bar]
[bar]
2000
6000
0.8
2
3
Connecting pipe dimensions:
– oil inlet
– oil outlet
– exhaust pipe of vacuum pump
[DN]
[DN]
[DN]
40
40
50/G2”
Oil temperature:
∆T at – 100% throughput
– 60% throughput
– 40% throughput
Operating temperature
[°C]
[°C]
[°C]
[°C]
27
40
80
40 – 65
Nominal suction cap. vacuum pump 45
Nominal suction cap. vacuum pump 170
[m3/h]
[m3/h]
160
160
Filter specifications
– Coarse filter (mesh grid)
– Fine filter with filter cartridge
– Fine filter with filter cartridge
[µm]
[µm]
[µm]
250
1 / 5
1 / 5
Net volumes
– entire plant (with options)
– degassing unit
– oil heater
– fine filter Pos. 25
– fine filter Pos. 125 (option)
[dm3]
[dm3]
[dm3]
[dm3]
[dm3]
865
645
155
23
23
Electrical power consumption
Heating unit
Heating Steps each
[kW]
[kW]
90kW
2 x 45
Audio pressure level (DIN 456335) dB(A) < 75

For the regeneration of the combined insulation (paper-oil) absorbers with high absorption and regeneration capacity are used.

References of new transformation units fitted and filled with new oil treated in the last 5 years by S.C. Electromontaj S.A.:

– 250MVA Roman
– 250MVA Bacau
– 250MVA Suceava
– 400MVA Sarat Lake – 2 pcs
– 200MVA Lake Sarat – 2 pcs
– 250MVA Oradea
– 200MVA Zalau
– 100MVAR compensation coil – Suceava

Among the old transformation units that have been revitalized over the past 5 years by S.C. Electromontaj S.A. we mention:

– 200MVA Hidroelectrica Stejaru (1962)
– 400MVA Termoelectrica Isalnita Plant (1967)
– 190 MVA Termoelectrica Simnic
– 16MVA Hidroelectrica Arpasu Plant
– 20MVA Termoelectrica Central Paroseni
– 40MVA CEZ Group Romania
– 40MVA Termoelectrica Isalnita Plant
– 20MVA Termoelectrica Isalnita Plant
– 40MVA Sodium Govora Plants
– 25MVA Daewoo

The method can be applied online and offline, but it is preferable to be applied online in order not to reduce the running times of the installations and to optimize the energy costs.

During the application of the insulation revitalization it is good, however, that the transformer is not fully charged but at about 50% of the capacity so that the oil temperature is about 40 ° C (this indication is not limiting but allows optimizing of the treatment time).

The method does not treat insulation at high temperatures or high vacuum, so it does not lead to premature degradation of the insulation, and it can be applied online (with the transformer in normal operation) allows the reduction of outage time.