6 Transformer Types You Can See In Commercial Installations
Transformers in commercial installations are normally used to change a voltage level from a utility distribution voltage to a voltage that is usable within the building, and are also used… Read more
Mar 16, 2015 | By Edvard Csanyi
Do Not Energize Oil-Filled Transformer Without Performing These 15 Tests and Checks!
The following tests and checks should be performed at a minimum to ensure that the transformer is ready to be energized. Do not energize the transformer without performing these tests… Read more
Feb 23, 2015 | By Edvard Csanyi
Basic Transformer Routine Test – Measurement of Winding Resistances
The resistance between all pairs of phase terminals of each transformer winding are measured using direct current. Furthermore the corresponding winding temperature is measured. The measured resistances are needed in… Read more
Feb 20, 2015 | By Edvard Csanyi
4 Essential Features of Transformer On-Load Tap Changer (OLTC)
On-load tap changers (or circuit tap changers), as the name suggests, permit tap changing and hence voltage regulation with the transformer on-load. Tap changing is usually done on the HV… Read more
Jan 28, 2015 | By Edvard Csanyi
An example of transformer overload and short circuit protection
Transformer protection consists of both overload protection and short circuit protection. Overload protection is usually accomplished via proper selection of the secondary overcurrent protective device. NEC Article 450 gives specific… Read more
Jan 21, 2015 | By Edvard Csanyi
Why cooling is essential for long transformer life?
As you already know, cooling is really essential for long transformer life. Most transformers are designed for 55°C or 65°C rise. Using newer insulations such as Nomex, temperatures of 95°C… Read more
Jan 09, 2015 | By Edvard Csanyi
Transformer routine test – Partial discharge measurement
This routine test aims to measure the partial discharges which may occur in the transformer insulation structure during test. Partial-discharges are electrical arks which form the surges between electrodes of… Read more
Dec 15, 2014 | By Edvard Csanyi
Mineral oil-filled distribution transformer as one of the main part of electrical supply system
As you already know, this is the most common type of distribution transformer. It is one of the most important part and can be found on electrical supply systems in… Read more
Nov 19, 2014 | By Edvard Csanyi
Maintenance and inspection of the transformer bushings
There are six different inspections to be performed on the bushings of the power transformer: Routine inspection Regular inspection (Once every two years) Inspection due to excessive partial heatings Local… Read more
Aug 01, 2014 | By Edvard Csanyi
Testing of Power Transformer – Measurement of Zero-Sequence Impedance
The zero-sequence impedance is usually measured for all star-connected windings of the transformer. The measurement is carried out by supplying a current of rated frequency between the parallell connected phase… Read more
Jul 21, 2014 | By Edvard Csanyi
Protection Against Overexcitation Of a Transformer
Overexcitation of a transformer means that the magnetic flux in the core is increased above the normal design level. This will cause an increase of the magnetizing current and the… Read more
Jul 02, 2014 | By Edvard Csanyi
An Example Of Transformer Tap-Changer Correct Adjustment
A 13800V/4160 V transformer has five taps on the primary winding giving -5%, -2 1/2 %, nominal, +2 1/2 % and +5 % turns. If, on-load, the secondary voltage reduces… Read more
Jun 13, 2014 | By Edvard Csanyi
A transformer is only as strong as its weakest link
Capacity (or rating) of a transformer is limited by the temperature that the insulation can tolerate. Ratings can be increased by reducing core and copper losses, by increasing the rate… Read more
May 26, 2014 | By Edvard Csanyi
Instrument transformers (CTs, VTs) in the system
The three main tasks of instrument transformers are: To transform currents or voltages from a usually high value to a value easy to handle for relays and instruments. To insulate the… Read more
May 19, 2014 | By Edvard Csanyi
The most common accessories you can find on oil filled transformer
Every oil filled transformer has a variety of accessories for different purposes. Here, I’ll try to name the most common of them, together with picture and description. Note that pictures… Read more
May 16, 2014 | By Edvard Csanyi