For this reason, the frequency converter should provide at least the RC-filter, which will ensure optimum period electric service. Modern inverters are equipped with inductive-capacitive (LC) or resistance-capacitance (RC) filters, so you can securely protect fuses that connect inverter with motor cable length of 100 meters there will be no voltage peaks above 850 V. In these conditions, almost any modern motor has an acceptable service life. – Appliances ensure the smooth start of the motor. From the connected to the motor scp enters nonsinusoidal current, which creates interference in the network. But since the time of acceleration / deceleration motor very briefly on practice, the noise imperceptible.
If the start-up phase lasts longer than 3 seconds, the temperature of motor windings increases and, consequently, reduces its life span. – Contactors for large machines. Start of large machines is carried out the method of the forward connection dol or the way the star-triangle ". The error may spark. If the contactors are opened, it creates a significant voltage spikes, which are dangerous for submersible motors in a very weak network. – The capacitors in industrial plants. In the industrial units established sophisticated regulatory instruments with numerous large capacitors that return peaks voltage network.
Danger to the submersible electric motors, these peaks represent only a case of too weak network. – Lightning. The defeat of the high-voltage network creates power surges, which are partially absorbed through conductor at the transformer substation and will be discharged to ground bus. If lightning hit the low voltage network, the risk of a surge of 10 to 20 kV only exists for the distribution cabinet pump. If the control cabinet and the motor itself is not protected, respectively, a lightning rod to ground, the installation may be corrupted. In areas where frequent lightning strikes, the best way to protect motors submersible pumps is that the drive side of the main circuit breaker to install a lightning rod and combine it with the rod or grounding, if possible, with water lifting tube wells in the event that this pipe made of steel. It should be noted that modern submersible electric motors, for example – grundfos ms 402, protection class up to 15 kV isolation. This – the maximum voltage that can pass through the motor, For example, when lightning strikes nearby. There is therefore no need for additional lightning protection, although there are not considered direct lightning strikes, which is unlikely. Using modern pumping equipment – not a tribute fashion, and the requirement of time. These units are reliable, have high efficiency, quickly recovered and are able to provide impressive energy savings. And in order to maximize these benefits, must take into account the accumulated experience of operating in a complex Russian environment. Prepared by the press service of the llc "Grundfos"