Brake unit suppliers remind you that both frequency converters and motors are high-power electrical devices. When current flows through the circuit, due to the presence of resistance, according to Joule's law, they will produce thermal effects and generate heat. High power currents often have a relatively large current, and there will be some heating phenomenon. Generally, it is judged that the hand does not feel hot. If it feels very hot, it should be dealt with in a timely manner.
Pay attention to the correctness of selection
The motor is the heart of equipment operation and the power source for almost all loads. When designing equipment selection, it is necessary to comprehensively consider the torque and power required by the load, in order to choose the appropriate motor power and torque. If the capacity of the motor is selected too small, it is equivalent to a small horse pulling a heavy vehicle. Of course, the motor itself is working in an overloaded state and will generate severe heat.
Similarly, if the specifications of the frequency converter are also chosen to be small, the frequency converter will still generate severe heat if it passes through currents higher than the rated current for a long time, and problems will quickly occur and burn out.
The selection is too small, so we can only replace it with a larger model to deal with it. This is a rigid requirement and there is no shortcut. It must be dealt with in a timely manner. Even if you dismantle the existing one and sell it as a second-hand, it is better to continue using it. After all, if there are problems that delay production or cause explosions or fires due to heating and other issues, that is a big deal.
Some loads may not seem heavy, but they involve frequent starting and stopping, which also requires power amplification to use, otherwise they will still face the problems mentioned above.
Equipment and load issues
If there is any abnormality in mechanical equipment or load, such as the gears or bearings of the transmission mechanism being damaged, the resistance will increase and the output of the motor will also increase. In some serious cases, motor stalling may occur, and the current will be very high. Although most frequency converters will cause overload and overcurrent, leading to alarm shutdown, there are also some in critical conditions, or if the protection parameters of the frequency converter are not set properly, it can still cause abnormal phenomena such as heating. In this situation, of course, we need to start with mechanical equipment and loads to solve the problem.
For example, the frequency converter controls some liquid conveying pumps or air supply fans. Due to dirty or bent pipelines, high resistance can cause excessive current in the motor and frequency converter. These need to be cleaned and treated in a timely manner.
Problems with the frequency converter and motor itself
If the motor is used for a long time, it cannot be ruled out that the insulation performance is poor or the bearings are stuck, which may cause high current and heat generation. The connection between the motor and the load may also be worn, or the motor may have three-phase imbalance, loose fixing devices of the motor, etc., which can cause abnormal noise and heating.
Aging of certain components in the frequency converter, deviation between vector parameters and motor matching, excessive setting of parameters such as torque boost, short acceleration and deceleration time, and low carrier frequency of the frequency converter may all cause the motor and frequency converter to heat up together.
The connecting wire between the motor and the frequency converter should generally not be too long, otherwise it will cause attenuation and waveform distortion. If it needs to be used, a dedicated frequency converter and an additional reactor should also be used to handle it.
In some situations where rapid braking is required, it is necessary to select appropriate braking resistors and braking units according to the braking power.
Long term work in low-frequency state
It is generally not advisable to design the motor to operate below 8HZ, even for vector controlled frequency converters, such use should be avoided as much as possible. This is mainly due to severe waveform distortion at low frequencies, which is too far from the sine wave, resulting in poor motor performance, severe torque attenuation, and heat generation. The target can be achieved by increasing the transmission ratio and then raising the output frequency of the frequency converter.
If it is necessary to work in a low-frequency state for a long time, a dedicated variable frequency motor can be used, or the motor can be cooled by forced air cooling or even water cooling.
Optimize the usage environment
In the past, due to poor economic conditions, many small factories did not design independent control rooms. Even if they had control rooms, they did not install air conditioning in the control rooms. Now that conditions are good, it is entirely possible to install frequency converters and other components in controllers with air conditioning. This way, the temperature of the frequency converter is at its optimal state, making it less likely to generate heat and extending its service life due to reduced dust and other factors. Overall, it is actually a relatively good investment.