Variable AC Output
A unit using a combination of transformers and other elements such as voltage regulating transformers can be used where variable AC voltage is required to control the power delivered to a process.
AC voltage can be regulated by a variac or voltage regulating transformer both of which will maintain the “harmonic free” nature of the supply sinewave.
The use of a buck/boost transformers can provide a wide range of options. In their simplest form, such arrangements vary voltage, bucking to reduce, or boosting above a nominal voltage. However, that variable voltage can be used to provide control of the applied voltage or current.
An example of such an arrangement would be for mains supply voltage product proving where one is required to vary the applied voltage above and below nominal supply. A buck/boost arrangement of say +/-10% may only have a self-capacity equivalent to the variation provided making it extremely competitive in comparison with a full capacity system.
If a number of different voltages are required then the addition of a tapped autotransformer could provide the necessary options.
Alternatively, for power control thyristor AC power regulators can also be used for this purpose and while they are faster to respond, they do introduce harmonics by omitting past of the sinewave to bring about voltage reduction.
Whether it is a simple, tapped requirement or individual control of each phase to close tolerances, whatever your specific needs, Admagnetics will be pleased to discuss your requirements with you.
Variable DC Output
If a variable DC voltage source is required then in effect the simple addition of a diode rectifier to a variable AC unit, with adjustment by taps, variac or voltage regulating transformer, would provide such a variable DC source.
However, it may be the case that your process would require a quicker response in the control scheme than could be provided by the combination of variable transformer and diode rectifier. In such case a thyristor controlled rectifier together with a fixed ratio rectifier transformer can be provided.
The various schemes available all have advantages and disadvantages and Admagnetics will be pleased to discuss these points, your process system and control requirements with you as part of the quotation process.
Whatever specific needs you may have Admagnetics will be pleased to talk over possible options with you to ensure you have the unit or combination of parts that best suit your needs.
It may be that you have an interesting problem in need of a solution and as such a unit or combination of elements of far more complexity could be required.
An example of such a case is where one wishes to distribute a single phase load evenly across a three phase supply.
Such three to single-phase converter arrangements are commonplace in applications where a heater is used to warm a pipe during the winter months. In this case, the load resistance is constant and therefore the Inductor and Capacitor values are fixed. Generally. the only control is to switch the circuit on and off to control the temperature of the heater. Three to single phase converters are used in this manner where a site has a number of single phase loads with the switch on and off independently but which are required to maintain a degree of balance in the loading of the three-phase supply system.
However, life becomes a whole lot more interesting if the load is variable and in that now it is necessary to provide variation in the Inductor and Capacitor elements to maintain a good degree of current distribution across the three phase supply.
Whatever specific needs you may have Admagnetics will be pleased to discuss your requirements with you.