1. Reason for overheating of high-voltage motor test bench
A high-power high-voltage motor must have a manufacturer with mature and limited technology, which can not only ensure the quality of the high-voltage motor, but also guarantee after-sales service.
During use, sometimes there may be situations where the working temperature rises and the variable frequency motor cannot work. What is the reason for the serious heating of the variable frequency motor?
There are many reasons for the heating of high-power variable frequency motors, mainly including power supply problems, load problems, motor failures, poor ventilation and heat dissipation, etc. 1. The motor is running under overload If the equipment is not matched and the load on the motor is greater than the rated power of the motor, it means that the motor is operating at overload. If the motor operates at overload for a long time, it is like a "small horse pulling a big cart", causing the motor to heat up.
When repairing an overheated motor, the first thing to do is to ensure that the load power is consistent with the motor power, and to explain whether the parameter configuration of the frequency converter is correct. Stop blindly calibrating and disassembling.
2. Causes and preventive measures of corona at the stator winding end of high-voltage motor test bench
The electric field diffusion near the slot of high-power motors is very similar to the voltage diffusion on transformer windings at high frequencies (overvoltage). If anti corona treatment is not carried out on the groove, a large amount of discharge charges will accumulate near the groove at the end, causing the electric field to gather and generate corona. Motor manufacturers usually use methods such as constant resistance ratio or non-linear resistance anti corona layer and inner screen anti corona layer to evenly distribute the electric field at the channel and prevent end corona.
After treatment with semiconductor resistor (or tape) on the groove, the voltage diffusion changes with the variation of its surface resistivity ρ s. As ρ s increases, the voltage diffusion becomes steeper and halo begins to appear; If the ρ S value is too small, a halo will appear on the outer side of the end of the anti halo layer. Its maximum value is usually 5x109 to 1010 ohms. The minimum value of ρ s is usually (1~5) x107 ohms
The electric field distribution of the first level constant resistance anti corona layer is still uneven. From the perspective of the magnetic core, the electric field propagation is relatively uniform. For motors with high rated voltage, second stage (or multi-stage) impedance corona materials can be used. The typical high resistivity ρ s2 is higher than the medium resistivity ρ s1
