Transformer ABC

Non Inherently Short-Circuit Proof - Transformers
means the transformer is equipped with an  internal "thermal protection device" to provide overload protection.

CSA
Abbreviation for: Canadian Standards Association.

Intrinsic heating
Heating up which is caused by power losses.

High voltage test
Method of inspection to prove the withstand voltage of an insulation between two windings.

IEC
Abbreviation for: "Internationale Electrotechnical Commission".

Small transformer, definition.
A small transformer with a power less 16 kVA, a primary voltage until 1000 Volt and a secondary voltage less than 1000 Volt is a so-called small transformer.

Conventional transformers
These types of transformers are made with laminated cores. The core plates been inserted into a bobbin carrying the windings.

Magnetically shielded winding
The magnetical shieldings do reduce the other magnetic leakage field.

No-load output voltage
do define the output voltage of the transformer w/o load at rated input voltage and rated frequency.

Non load power losses
do define the active power loses at rated input voltage and rated frequency w/ load.

Rated Power
Do define the sum of all output voltages.

Rated ambient temperature
do define the max. ambient temperature which shall not be exceeded during normal continuous operation.

Non-short-circuit proof transformer
Specify a transformer w/o internal protective device. Appropriate external protective equipment has to be installed.

Primary winding
is designed to be connected to the AC power line.

Toroidal transformer
A tape wound insulated steel core where the magnet wire is directly wound on the core by use of special machines.

Protection class I
Transformer classified to protection class I provide connection to protective earth neutral (PEN).

Protection class II
Transformer classified to protection class II provide protection against dangerous currents are double or reinforced insulated and do not provide connection to a protective earth neutral (PEN).

Secondary winding
are windings designed to be connected to the load.

Static shielding
made by a layer of metallic tape (usually made by copper tape) between two windings to reduce transmission of electrostatic interference. The static shielding distinguishes from the magnetic shielding.

Protective Screen
Seperation of dangerous active parts via intercostals metal part which is connected to the outer protective earth neutral (PEN).

Static screen
The static screen is used to suppress interferences from the AC power line.

Symbols - Directory

 
 
 
 
 
 
Volt
[V]
Ampere
[A]
Voltampere
[VA]
Hertz
[Hz]
Safety insulation transformer. Non-short-circuit proof.
Safety insulation transformer. Non -inherently -short-circuit proof.
Insulation transformer. Non-short-circuit proof.
Insulation transformer. Non -inherently -short-circuit proof.
Power transformer. Non-short-circuit proof.
Power transformer. Non- inherently-short-circuit proof.
Protective insulation (Protection class II)
SEV
Abbreviation for: "Schweizer Elektrotechnischer Verein".

Autotransformer
Transformer where input and output-windings are combined in one winding.

Safety insulation transformer
Transformer for safety extra-low-voltage (SELV).

Transformer with separate winding
Transformer with galvanic-insulated primary and secondary winding.

Insulation transformer
Transformer with double or unforced insulation between primary and secondary winding.

Thermal fuse
Fuse which opens an electric circuit irreversible after reaching the cut-off temperature.

Temperature switch
Switch which opens an electrical circuit reversible after reaching the cut-out temperature. After cooling down electrical circuit will be closed again automatically.

UL
Abbreviation for: "Underwriters Laboratories".

Ambient temperature
Ambient air temperature surrounding the transformer.

VDE
Abbreviation for: "Verband Deutscher Elektrotechniker"

Power losses
Difference between total input power (primary) and total output power which will be dissipate into heat.

The power losses be composed by:
-Iron losses (in the magnetic circuit magnetization and eddy-current losses )
-Copper losses (losses caused by the electrical resistance of the windings)

Efficiency

Ratio between total output power (secondary) and total input power (primary).