Accessories for liquid immersed transformers

 

A wide range of accessories suitable for different purposes, from safety protection to special control of life parameters of your transformer.  
Below our standard and on request devices.

 


Standard accessories

  • 4 bidirectional wheels
  • 2 grounding terminals
  • 1 identification plate
  • 2 or 4 lifting lugs (according to the rating power)
  • 4 connections for haulage
  • No load tap changer

Accessories upon request


Safety devices


Oil temperature indicator

Where: All types of transformers

DescriptionDevice used to measure the top oil temperature in the tank by a sensor. It can be provided with 2 or 4 SPDT switches.


Winding temperature indicator

Where: All types of transformers

Description: Device used to measure the winding temperature in the liquid immersed transformers by indirect way using thermal image tecnology. It can be provided with max 4 SPDT switches.


Buchholz relay

Where: Transformers with conservator

Description: This device intercepts and collects any gas bubble coming from the inner side of the transformer (indicating short circuit or other inner faults) and/or signals any oil leakage from the tank, giving an alarm signal or tripping one. There are different options according to the dimension of the pipe connecting flange. It is possible also to connect a gas sampling device with Buchholz relay to collect the gas for the analysis. 


Air breather

WhereTransformers with conservator

Description: The aim of this device is absorbing the humidity air that the transformer sucks during the thermal contraction of the liquid in order to guarantee a better dielectric capacitance. There are different dimension and connections according to the oil contained in the conservator; when the salt becomes green means it is satured by humidity.


Oil level indicator

Where: Transformers with conservator

Description: This device gives a visual signal of the oil level in the conservator. There are different options according to the dimension and the type of conservator; it is also possible to signal the max and/or min oil level by switches.


Pressure relief device

Where: All types of transformers (smaller PRD without contacts can be available also for hermetic transformers)

DescriptionIn case of sudden and violent internal short circuit the insulating liquid produces a large volume of gas that should be evacuated in order to avoid the explosion of the transformer. By means of PRD it is possible to evacuate the oil. There are different types with dimensions according to the oil quantity contained inside the tank of the transformer; it is also possible to signal the opening of the PRD by switches placed on its cover.


 

DGPT2 or RIS

Where: Hermetic transformers

DescriptionDevice used for keeping under control pressure, temperature and level of the liquid inside the transformer tank.


Shutter valve

Where: Power transformers with conservator 

DescriptionDevice used to block the escape of oil coming from conservator in case of leakage in the transformer tank. It is interposed between the Buchholz relays and the conservator. It can be set with alarm and trip signals according to the flow valve setting.


Flow indicator

Where: Power transformers with conservator 

DescriptionDevice used to control of the oil flow out of the pumps on transformers with forced oil cooling equipment. It is used also in water cooled transformers. A small flow indicator is also available for distribution transformers.


Antivibrating pads

WhereDistribution transformers 

Description: Accessories to be assembled under the wheels in order to reduce noise and structural resonances.


Marshalling box + Electrostatic screen

Where: Distribution transformers

Description: Marshalling box centralizes the auxiliary services and protects the terminal board.
Electrostatic screen allows a strong reduction of the capacitive coupling between MV and LV windings and also a reduction of overvoltages transferred among the same windings.


 

Overvoltage protection devices

Where is used: All type of transformers

DescriptionThe aim is to protect the regulating winding. There are 2 possibilities: using surge arresters located close to the terminals as much as possible or using spark gaps on the bushings.


Electronic safety devices


To have an instant control on all essential parameters of the transformer SEA can provide part of the accessories with

Analog output 4÷20 mA or RS485 digital output Modbus protocol

 

 

 

 

 

 

 

 

Please contact our Sales department for additional informations


Bushings


Elastimold bushings

Where: Distribution transformers

DescriptionThe plug connection allows a very rapid connection of the cable to the transformer and can be touched when the transformer is under voltage. They are manufactured according to the Standards EDF HN 52 S 61 - CENELEC EN-50181-50180 - IEEE 386-1995 - UTE C 66-555 - DIN 47636. Always specify in your request the type of rapid connection desired.


Busbars

WhereDistribution transformers

DescriptionSuitable for indoor and outdoor application with protective cap. They are manufactured according to the Standards EN 50387, ENEL DJ1107-1109 and BS 2562/1979. 


Inner cone bushings

WhereDistribution transformers

DescriptionSuitable for indoor and outdoor application with protective cap. They are manufactured according to the Standards DIN 47637 - ENEL DJ1111 and DJ1108.


Porcelain bushings

Where: All type of transformers 

DescriptionOil to air bushings used to bring the connection from the transformer insulation medium to the external insulation medium. Suitable for voltages up to 45 kV.


Pfisterer bushing Pfisterer bushing

 

Elbow bushings

Where: All type of transformers 

Description: These connecting pieces are fitted instead of the porcelain bushings on the medium voltage side of distribution or power transformers.


Composite bushings

Where: All type of transformers 

DescriptionOil to air bushings used to increase general safety level; it is possible to use such bushings made of composite material instead of porcelain in order to guarantee no oil leakages, no risk of fire, possibility to be assembled horizzontally and control of partial disharges. They are interchangeable with porcelain bushings in compliance to EN 50180 and suitable for use according to C5 corrosiveness class with reference to ISO 12944. Remark: this bushing is not a condenser bushing but it can provide the voltage signal through a capacitive socket.


Condenser bushing

Condenser bushings

Where: Power transformers 

DescriptionBushings suitable for voltages from 25 to 52 kV or higher. It is possible to get an active control of voltage distribution between the central high voltage lead and the external flange.


High current bushings

Where: Power transformers 

DescriptionBushings up to 30 kA. Their aim is conducting heat by the central massive conductor.


Automatic voltage regulator


AVR

Where: Power transformers with OLTC

DescriptionThis device is used to mantain a stable voltage on the load side of the power transformer when the network conditions are varying. AVR measures the control voltage of the transformer and regulates the on load tap changer consequently. 3 functions in 1 device: measuring, controlling and regulating.  


Cable boxes


Where: Distribution transformers

DescriptionBoxes used to protect bushings according to the International Protection rating.

SEA can offer the following configurations:

 

Type A

Standard version: IP 41

Option 1: Cable box with rating IP 55 (for higher ratings please contact us)

Option 2: Internal busbars for cable incoming from below

Option 3: Cable glands


Type B

Standard version: IP 41

Option 1: Cable box with rating IP 55 (for higher ratings please contact us)

Option 2: Internal busbars for cable incoming from below 

Option 3: Cable glands 


Type C

Standard version: IP 41

Option 1: Cable box with rating IP 55 (for higher ratings please contact us)

Option 2: Not available

Option 3: Cable glands


Type D

Standard version: IP 41

Option 1: Cable box with rating IP 55 (for higher ratings please contact us)

Option 2: Not available

Option 3: Cable glands