Tuesday, January 26, 2010

Pole Mounted Sub-Stations

I was going around town, with a colleague, we came across a structure which by the roadside that my friend was quick to refer to as transformer. I quickly corrected him that its actual name is not a transformer as many might call it, rather it’s called a Pole Mounted Sub-Station.

A Pole Mounted Sub-station is a large, free standing, outdoor electrical equipment that is mostly located in residential places. Its main purpose is to step-down the lethal 11kV to 415/240V for light, commercial and residential loads (consumers)...

The 11kV line is connected to the Step-Down Transformer (11kV/415V) though a gang isolator and fuses. The lighting arrestors are installed on the H.T side to protect the Sub-Station from lightening strokes. The transformer steps down the 11kV to 415V, 3phase, 4-wire supply. The voltage between any two lines is 415V, and between any line and a phase is 240V. The Oil Circuit Breaker (O.C.B), installed on the L.T side automatically isolates the transformer from the consumers in case of any fault. The Pole Mounted Sub-stations are generally used for transformer capacity up to 200kVA
They should be periodically checked for dielectric strength of oil in the transformer and (OCB)
In case of repair the transformer or (O.C.B) both the Gang Isolators and (O.C.B) should be shut off.
This equipment is very expensive leading to the reason why people vandalize them. The Step-Down Transformer is oil cooled and its this oil that people steal. This costs the distribution company millions of 
Shillings annually. Please be warned that the current flowing through the transformer is deadly, it would kill you in seconds. Stealing that oil means that the transformer will overheat, reduce its efficiency and 
possible explode under normal circumstances. In case you spot any one 
vandalizing the equipment please call The Kenya Power and Lighting Co. Limited: www.kplc.co.ke.
See the image below of a Pole Mounted Sub-Station.


  1. log on to engmoriz.blog.com

  2. hi my name is darlington evans and im looking for the POLE MOUNTED SUB STATION transformer with a range from 50kva for farmhold and commercial use. Could u please supply any details and information where i could buy them. they have to be oil cooled. Thax darlington

  3. Wilfred G.May 11, 2010

    This comment has been removed by a blog administrator.

  4. To:Darlington Evans.

    The PMTx(Pole Mounted Transformer) 50kVA Range can be available at:

    1. http://cnliantong.en.alibaba.com/
    They produce quality transformers.
    2. http://www.powertransformer.us/ gesubstationtransformers.htm

    Please give me your location so that I may give u detailed information depending on your location.

  5. Hey
    Can i know more about you..Do u have any contact information.
    11KV Lightning Arresters

  6. Yes my contacts are in the 'About Me' page.
    My email: w4cool@gmail.com

  7. hi Wilfred my location is united kingdom
    thanx Darlington

    my email is darlingtonevansgondo@yahoo.co.uk

  8. what type of transformer are used for this pole mounted sub station.i mean dealt or star..
    explain me clearly plz..

  9. For Pole Mounted Substations, the transformer is a step-down in nature, therefore the connection is a Star-Delta.That is, the primary winding is connected in Star and Delta for secondary.

  10. Dont' see alot of pole mounted step down transformers like that.

  11. Hi, what a great web blog. I usually spend hours on the net reading blogs on various subjects. add some more content in your blog .
    Three phase transformers

  12. Many thanks for the exciting blog posting! Great job, keep it up.. Substation Transformer

  13. Extraordinary explanation. I liked it.

  14. An electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers.
    Power transformers in India | Transformer manufacturer in India