Oil filtration

Molecular sieve dryers
Peltier effect breather
Oil filtration services

Any transformer may absorb moisture to the point at which positive action needs to be taken. Powermann can provide in-house filtration services for small transformers, or procure specialist sub-contract services for large transformers. The company can provide in service breathers to limit the ingress of moisture and dryers to remove moisture at a steady pace over a prolonged period of in-service use. 
 
Speak to our engineers to discuss your specific requirements. 

Molecular sieve dryers
 
A typical 75MVA oil filled HV transformer may contain 46,000 litres of oil and 4,000kgs of paper in the form of wraps and blocks. After continued service this transformer may have 4% by weight of water in its solid insulation. Typically this would be distributed 160 litres of water in the paper and perhaps two litres in the oil. Water can be removed relatively quickly from the oil, but very much more slowly from the paper. So that to be effective any drying system used must be attached to the transformer for a long period of time. Powermann offer advice on unit size and the drying program for particular transformers.  
 
Cellulosic/dielectric fluid insulation systems of power transformers can, unless specifically protected, become grossly contaminated with atmospheric moisture. Such contamination usually occurs over a long period of time perhaps twenty-five years or so, but can under cyclic loading conditions with associated large swings in top oil temperature, occur more rapidly. Water contamination, mechanically weakens paper wraps and spacers used in the constructions of power transformers, contributes to oil sludging and in droplet form migrates to areas of high stress, where there is a possibility of it being involved in a catastrophic electrical breakdown with consequent loss of the power transformer. The Omnia molecular sieve dryer has been designed specifically for fluid filled power transformers that have become grossly contaminated with water.

Molecular sieve drying:
All molecular sieves are synthetic zeolites that are activated by heating to drive off water from cavitites.

Peltier effect breather

Cellulosic/dielectric fluid insulation systems of power transformers can, unless specifically protected, become grossly contaminated with atmospheric moisture. Such contamination usually occurs over a long period of time perhaps twenty-five years or so, but can under cyclic loading conditions with associated large swings in top oil temperature, occur more rapidly. Water contamination, mechanically weakens paper wraps and spacers used in the constructions of power transformers, contributes to oil sludging and in droplet form migrates to areas of high stress, where there is a possibility of it being involved in a catastrophic electrical breakdown with consequent loss of the power transformer. The Omnia breather has been designed specifically for use with conservator type power transformers, it removes water from the conservator air space and in so doing exerts a drying influence on the oil and in turn the paper insulation.
 
Dryer equipment:
One finned cast aluminium dryer and strut for single flange mounting
One pipe and flange
One control cabinet fabricated from 316 stainless steel
One ten meter length of Interconnecting cable

Power supply:
Single phase 50Hz.220-240 volts. 120 watts
 
Principle of operation:
A thermosyphon circulation of air from the space in the conservator is promoted by cooling of a central duct system by means of thermo-electric modules. Water vapour and any volatile acid vapours are condensed on the inside walls of this duct system and form frost. A defrost cycle is automatically triggered every 7 hours, heating the duct to release the condensed and frozen vapours through a vent to atmosphere.
 
Capacity:
The breather is recommended for use on power transformers with a total oil quantity of up to 90,000 litres of insulating oil.

Oil filtration services
 
Powermann's in-house mobile oil filtration unit is capable of filtering 500 ltrs of oil per hour. If greater capacity is required specialist sub-contractors like Electrical Oil Services are available. Advice and site services can be supplied for specific projects on request.

Oil condition assessment:
Powermann uses a number of laboratories for the analysis of insulating and lubricating oils. The service is complete from sample collection, testing and report analysis.