In startup, it is important to ensure that the firing angle that each pair of thyristors count is electronically controlled in order to concentrate a variable voltage at the motor terminals during the acceleration process.
Over the years, the advancement of electronics has ensured the creation and projection of diverse components, such as the solid-state starter, consisting essentially of a set of pairs of thyristors, or combinations of thyristors and diodes, with one at each motor power terminal. CASC25
Thus, it is possible to be able to sustain the starting current at the line near the nominal line and with a subtle variation. In addition to the advantage of voltage or current control during the start of the match, the electronic key also has the convenience of having no moving parts or bows, as in the case of mechanical switches.
At the end of the starting period, normally adjustable on average, between 2 and 30 seconds, the voltage can reach its full value after a subtle acceleration or an ascending scale, as opposed to being exposed to sudden increases or jumps.
The thermal protector is applicable to three-phase electric motors, but only to machines with a Y-connection. The advantages are current and temperature sensitive protector adjustment and the possibility of automatic reclosing. The drawbacks are based on current limitation, because the protector is connected directly to the coil of the single-phase motor and has its application facing three-phase motors only in the center of the Y-connection.
These protectors are bimetallic type elements that have closed contacts, used mainly in single-phase induction machines, with the task of preserving the same against overheating caused by overloads, which can generate the rotor locking and voltage drops.
The thermal protector on a bimetallic disc has two moving contacts, a resistance and a pair of fixed contacts. The protector is connected in series, with a power supply, through thermal dissipation, which is caused by the passage of current, through the internal resistance a deformation of the disk causes the contacts to open and the motor power is automatically interrupted.
After a lower than specified temperature is reached, this protector must be reconnected. Due to this reclosing, you can have two types of protectors, the protector with automatic reclosing and the protector with manual reclosing.
To avoid very long starts it is necessary to avoid very long starts, which occur when the electric motor torque is only higher than the strong torque. The overcurrent current absorbed in relation to the rated speed is not reached and can cause the motor to heat up. hose reel parts
It is necessary to keep the load coupled to the motor under proper operating conditions, avoiding the presentation of an abnormal resistant torque and in the case of an industrial process, frequent starts will be essential, and this characteristic must be present in the design of the equipment, and the motor must be adapted so that you can act in this way.
Thus, due to the regulators of some machines, it may be necessary to make several starts in a relatively short time, preventing the motor from cooling properly. Therefore, counter-current braking, by inverting the motor, generally represents the cost equivalent to three starts. In all cases, it is necessary to ensure that the starter torque is sufficient, by choosing a suitable motor, or by checking that the power line has specifications necessary to limit the drop in voltage at startup.