In 1820, the Danish professor Hans Christian Oersted, realized an experience in which it demonstrated for the first time the relation between electricity and magnetism. The experiment was to place a magnetized needle parallel to a wire that would be traversed by an electric current. Thus, Oersted observed that, upon closing the circuit key, the wire was driven by an electric current, and at that instant the needle immerged deflected its north-south orientation.
This fact had already been observed when a magnet was approaching a magnet needle, when the key was opened, the current flow stopped and the needle returned to its normal position, in this way the relation between electricity and magnetism was discovered.
In the eighteenth century, the American scientist Benjamin Franklin had attempted to explain the electrical phenomena of attraction and repulsion. In his theory, he accepted that all bodies had a kind of “electric fluid,” responsible for such phenomena.
By having friction, some bodies lost that fluid, others received it and without friction, these bodies remained in their neutral state with equal numbers of negative and positive fluids. According to these ideas, since it is a matter of transferring electricity from one body to another, there would be neither creation nor destruction of electric charges, the total amount of electric fluid being constant.
Compound excited electric motors are used where there is a need for constant speed with extreme load variations and in order to combine the best of the parallel connection with the best of the serial connection, for this there is the composite connection. We achieved optimum parallel engine speed regulation with the excellent starting torque of the series engine. Browning 1VP68X
In general, we can say that depending on the application, DC drives have the greatest benefits in terms of reliability, user friendly operation and dynamic control, such as:
– operation in four quadrants with relatively lower costs;
– continuous cycle even at low speeds; high torque at start and low revs; wide variation of speed;
– ease in speed control;
– AC / DC converters require less space;
– flexibility (different types of excitation);
-relative simplicity of modern AC / DC converters.
The function of the composite motor is to make it possible to take advantage of the high torque of the series connection, without speed shots with reduced loads or no load, then apply the low speed variation of the parallel motor under different load situations.
Soft-starter electronic equipment is the starting device for induction motors, all in a solid state, ie based on semiconductor switches. The principle of operation of the soft-starter is, like electromechanical systems, to reduce the initial starting voltage and how the torque is proportional to the current, and that to voltage, the electric motor will start with reduced torque. As a rule, the soft-starters have acceleration ramp adjustment. This adjustment can be done via potentiometer or HMI (Human Machine Interface). A5835 OLP
Static starters are microprocessor keys designed to accelerate or decelerate and protect three-phase induction motors and by setting the thyristor firing angle, we control the effective voltage applied to the motor. With correct adjustment of the variables, the torque and current are adequate to the needs of the load, ie, the required current will be the minimum required to accelerate the load without changes of frequency. Some features and advantages of the soft-starters are the setting of the starting voltage for a predefined time, the starting voltage pulse for loads with high starting torque, fast voltage reduction at an adjustable level, protection against phase overcurrent and undercurrent.