|
The voltage variator is mainly comprised of a
toroidal core manufactured using magnetic sheeting with very low loss
and high permeability, wound at an angle of approx. 340º. The contact
guide is comprised of an evenly wound coil, that is trued up, polished
and treated with a silver bath to improve the contact with the graphite
brush. This treatment allows for the reduction of the contact resistance
and the rusting of the copper which leads to a longer useful life of
the voltage variator.
The following factors work towards our voltage variators operating with
an optimal degree of effectiveness and durability:
 A high
number of turns per volt, which allow us to set extremely precise voltage
values.
The
epoxy resin encapsulation packing allows for an improved dissipation
of heat, avoiding the concentration of this at the contact point of
the brush (as occurs with the air-wound variators) and in addition it
protects the variator from the harsh environmental factors of certain
noxious surroundings.
The
inside and outside friction contacts are generously designed to dissipate
the maximum possible amount of heat with the minimum of wear.
Both
the motorisations and the mechanical stops have been subjected to mechanical
resistance tests, which guarantee their effectiveness in the diferent
applications they are used for.
The toroidal
voltage variators do not distort the sine-wave signal.
The increase
in the external non-metallic parts varies between 45º and 60ºC,
above the environmental temperature at full load (fig. 2), neverthless,
there are many means to reduce this temperature, such as an oil bath,
fan cooling, although these systems are usually used in high-power variators.
The voltage
variators allow for the adjustment of the voltage without surpassing
the nominal intensity, except at the beginning and the end of the range
which may be surpassed by up to 22%, as shown in the graph in figure
3.
|
|
Magnetic
characteristics
The toroidal
core is manufactured using top-quality, very low loss, high yield magnetic
sheeting, and is subjected to a heart treatment in order to achieve
an induction capacity of some 16,000 Gauss, although to improve performance
we subject it to 15,000 Gauss.
In figure 4 we can observe that the saturation curve of a voltage variator,
is at approximately 15% of the nominal voltage rating of the device,
assuming a power supply voltage of 230V.
In the toroidal voltage variator the magnetic flow is concentrared within
the core in an even manner, and as there are no intermediate metal parts,
vibrations are eliminated.
The voltage
variators manufactured by TORIVAC are designed
to operate at 50/60Hz., even though the quality of the magnetic sheeting
and the heat treatment we subject it to, allow it to operate at frequencies
close to 400Hz taking into account that the hysteresis losses increase
considerably.
|
