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In order to correctly identify the
product, hereunder are the definitions of the EN 60742 and IEC
989 regulations:
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TRANSFORMER:
static equipment based on electromagnetic induction. It is made
of two or more windings meant to transform a voltage system (alternating
current) into another equivalent one, usually of different values
and with the same frequency, in order to conduct electric power.
a) Insulation:
transformer with a separate protection between input and output
coils.
b) Safety:
insulation transformer meant to supply safety extra-low voltage
circuits.
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AUTOTRANSFORMER:
a special transformer where coils are not separated galvanically,
where there is one coil only with an appropriate power - points
socket serving a double function of primary and secondary coil.
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INDUCTANCE:
a component used in electric lines to change the characteristics
of power factor and undulation.
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REACTANCE:
a winding which, once inserted into the electric line, leads to
programmed changes of voltage and current, as a result of its relative
component. In other words, it generates electric effects which are
not in phase with the input ones.
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IMPEDANCE:
a standard component to be inserted into the electric line, to obtain
a more balanced full load, compensating thus for any excessive capacitive
effects in the line.
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SAFETY EXTRA-LOW VOLTAGE:
a voltage not higher than 50V., which is an effective value in alternating
currents; or 120 in direct stable current among conductors, or between
earth and any conductor, which is to be separated from the power
mains by means of a safety transformer.
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NOMINAL POWER:
it is the result of the nominal secondary voltage multiplied by
the secondary nominal current or, in case of polyphase transformers:
where: n= number of phases, V2= nominal secondary tension, I2= Nominal
secondary current.
If the transformer has more than one secondary winding, or it is a
multiple socket transformer, the nominal power will be the sum of
the results of the nominal voltage multiplied by the nominal secondary
current of circuits that can be simultaneously loaded. |
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NO-LOAD POWER:
it is the power absorbed by the idly running transformer, supplied
at primary nominal voltage and at nominal frequency.
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PRIMARY NOMINAL VOLTAGE:
supply voltage given to the transformer for its speci?c working.
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RANGE OF PRIMARY NOMINAL VOLTAGES:
the range of primary voltages supplied to the transformer, and expressed
by its low and high thresholds of 230-400 Vac.
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SECONDARY NOMINAL TENSION:
secondary voltage for the transformer when it is supplied at primary
nominal voltage, at nominal frequency, with the secondary nominal
voltage and the nominal power factor. (This value is less than the
voltage measurable without the applied nominal load).
This change of voltage is directly proportional to the transformer
impedance and to the supplied load specification.
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SECONDARY NO-LOAD VOLTAGE:
secondary voltage of the transformer idly functioning at the primary
nominal voltage and at the nominal frequency.
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SHORT-CIRCUIT VOLTAGE:
voltage to be applied to the primary winding, so that the secondary
one, connected in short-circuit, is inducted with a current equal
to the secondary nominal voltage, while the windings are at ambient
temperature.
The short-circuit voltage is usually expressed in percent of the
primary nominal voltage.
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SECONDARY NOMINAL VOLTAGE:
it is the secondary current, with primary nominal voltage and nominal
frequency. It is assigned by the manufacturer to the transporter
for its speci?c functioning. If not specified, the secondary nominal
current can be deduced from the nominal power and the secondary
nominal voltage.
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| STANDARD TRANSFORMER and INSULATION CLASS |
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BASIC:
it is the insulation of the live parts, to guarantee the essential
protection against direct and indirect contacts.
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SUPPLEMENTARY:
it is an independent insulation in addition to the basic one, in
order to guarantee a protection against direct and indirect contacts
in case of faulty basic insulation.
a) Double:
DOUBLE: it includes both the basic insulation and the supplementary
one.
b) Reinforced:
it is a single insulation system of the live parts, which guarantees
a protection level against direct and indirect contacts equivalent
to a double insulation.
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OF CLASS I:
a transformer where the protection against direct and indirect contacts
is not based on the fundamental insulation only, but also on a safety
measure achieved by connecting all the conducting parts accessible
to earth by means of an appropriate terminal.
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OF CLASS II:
a transformer where the protection against direct and indirect contacts
is not based on the basic insulation only, but also on supplementary
safety measures through a double or reinforced insulation.
These measures do not include earthing, and do not depend on the
type of installation.
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OF CLASS III:
a transformer where the protection against direct and indirect contacts
is based on the power supply and safety extra-low voltage, and no
voltages higher than this are created.
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SHORT-CIRCUIT RESISTANT MADE:
a transformer where the over-temperature won't exceed the specific
limits when it is overloaded or short-circuited and after the overload
and short-circuit removal it will keep on working.
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INHERENTLY SHORT-CIRCUIT PROOF:
a short-circuit resistant transformer, equipped with a protection
device which opens the primary and secondary circuit or reduces
the "circular" current: the equipment starts to function
normally after the elimination of the overload or short-circuit.
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BREAKDOWN PROOF CONVEYOR:
a transformer that is no more functioning because of an abnormal
use without causing any danger for the user and the adjacent parts.
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THERMAL INSULATION CLASS:
it is the winding enamel resistance to the over temperature arising
during normal functioning.
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