Knowledge Base > FAQ's

FAQ's Transformer

1) What is a transformer? 

Transformer is a static device which transforms voltage from one circuit (primary) to other circuit (secondary) where two circuits are interlinked by a common electromagnetic field, created by alternating current flowing in one circuit (primary winding).Primary and secondary voltages depend upon the application. Current in windings depend upon the power and voltage of a particular circuit.

2) What is an electronic transformer?

There is no Electronic Transformer as such. But transformers are required in Electronic Equipment for various purposes such as step down transformer, auto transformer, isolation transformer, transformers for rectifier circuits etc. The operating frequency ranges from 50/60HZ to many Kilo Hz or Mega HZ

3) Can transformers be operated at various frequencies?

Transformers are designed for a particular frequency as required by use. Transformer designed for higher frequency cannot be used at lower frequency. But a transformer designed for lower frequency can be used for higher frequency subject to many considerations and limits on performance.

4) Can transformers be used in parallel?

Transformers are frequently use in parallel in power system but voltage ratio has to be equal. The load sharing between two transformers depend upon their impedance.

5) Why is the transformer case hot? 

Resistance of transformer winding is responsible for generating watt loss. Similarly transformer core also contributes to watt loss in magnetic circuit. There are other types of losses such as Eddy Current loss, Stray loss etc. All these losses generate heat and temperature of winding, core, enclosure increases.
Humming noise is created by electromagnetic circuit and core. Wherever it is required and essential it can be minimized by dampening pads (for small transformers).

6) What is an isolating transformer?

Isolation transformer means any transformers where two winding are isolated from each other electrically.

7) Can I connect a single-phase transformer to a three-phase source?

No you cannot connect single phase transformer to three phase circuit without confirming circuit configuration. Transformer primary designed for line to line voltage can be connected across two phases. Transformer designed for phase to neutral voltage can be connected across phase and neutral.

8) What is the inductance of a transformer?

Winding of transformer associated with electromagnetism will have Resistance, Inductance and Impedance. These parameters depend upon various factors such as frequency, physical dimensions, operating flux density.

9) Why did my transformer blow the moment it was installed?

1) connected to higher voltage than it was designed for.
2) There was a short circuit on load side.
3) There was a fault in the transformer.

10) Why do we need transformers?

Electricity is generated at a particular voltage as per standard practice prevailing in that country. Then it is raised to high voltage for transmission over long distances. Then at receiving stations it is reduced to lower value. From there it further reduced for distribution at lower value. Finally it distributed at low voltage. Transformer never changes frequency.
Generation voltages-3.3 KV, 6.6KV, 11KV (ONE KV MEANS 1000 VOLTS)
Transmission Voltages-400KV, 220 KV,132KV,110 KV,66KV
Distribution voltages-33KV, 22KV, 11KV, 6.6 KV, 3.3KV
User side voltages- 440/415 Volts three phase,220 Volts 3 phase,110 Volts 3ph(Japan and some countries),230/240 Volts 1 phase,110Volts 1 phase,63.5 Volts 1 phase

11) What is an inductor? How do inductors behave? How do you protect against inductive kick-back? 

Inductor or Reactor or Choke is a coil with air core or magnetic core. Inductance is measured in henries. Rise of current is delayed due to inductor. Chokes are used for many purposes. Current limiting chokes, filter chokes, chokes for harmonic suppression etc. Choke or Inductors are used in AC/DC Drives, Invertors, Power System, lighting circuits, Furnaces. Frequency, voltage and inductance depend upon use.
Inductance varies from Micro henries to Henries. Rating may vary from changes from 1VAR (Volt-ampere) to 40000KVAR (1 KVAR IE EQUAL TO 1000 VAR)

12) What is Step up Transformer? 

Step up transformer voltage of primary is raised to higher value in secondary winding. In step down transformer Voltage of primary winding is stepped down to lower value.



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