Pad mount transformer filter press 1

[voltsOO6]

I'm going through our specs on pad mounted oil filled transformers and came across the term filter press connection.

Does anyone here know if the filter press is actually on the transformer oil compartment itself or is just a connection to connect an external pump and filter?

 

[Zogzog]

A filter press is an exernal rig used to porcess your oil if necessry.

 

[oldfieldguy]

What Zog said-

Typically a connection in the gas space for an oil processing unit, in addition to the connection at the bottom occupied by the drain plug.

Some people (me included) tend to rtreat pad-mount transformers below 1000kVA as commodity items and do not do a whole lot of testing on them, including oil processing.

old field guy

 

[Millbo]

Volts006

You may have heard them refered to as "Kidney pumps".

One common model I've mounted on OLTC compartments before is this one (see link).

http://www.velcon.com/systems/system.html

Pending on the model/type they can filter out particles, remove water, degass...etc

Hope that helped.

 

[voltsOO6]

Thanks, Millbo and oldfieldguy. Those are great tips. Any idea of the size of the connection required for the pump?

We had a transformer shop drawing and the manufacturer listed 1" drain and fill plugs. Whereas our spec indicated provide filter press connections and I had a tough time trying to verify if the 1" drain and fill plugs met our spec requirement for 'filter press connections'.

 

[oldfieldguy]

1" is good enough for most purposes.

Pump hardware might be different, but every contractor I've ever used for oil work had a bucket full of fittings to adapt his rig to the transformer in question.

That Velcon "kidney pump" is a great unit. I've seen then on load tap changers that saw a lot of action. It would be very much overkill on a pad-mount transformer.

Recently a very well known company in the transformer oil biz here in the states tried to sell us on-line oil processing for some of our transformers in the 2500 kVA range. Considering that said transformers had been in service since 1980 and only now showed moisture bumping the allowable limit, I elected not to buy his on-line processing and hired another company to come in and do a dehydration.

old field guy

 

[prc]

Pad mounted transformers are covered under ANSI/IEEE C57.12 series standard numbers 25( single phase up to 167 kVA),26(3 phase up to 2.5 MVA) & 34 (3 phase up to 5 MVA compartmental type) For 3 phase units 1 inch NPT upper plug for filling and 1 inch NPT drain plug are standard.When size is above 750 KVA, built in sampling device is provided with drain plug.

In other countries,say India, valves are preferred to plug .Above 10 MVA 2 inch flanged valves are standard and below 10 MVA 32 mm valves are standard. The upper and lower plug/valves are used for connecting to filter machine when oil is reconditioned to get adequate oil BDV and water content.

Kidney pumps (on-line filteration devices) are OK for OLTC diverter switch oils,but not very effective ( as volume of water removed is so low compared to total water in paper)in drying out paper insulation in main transformer esp in case of very large units.