1. The power and temperature rise of the motor
Regardless of the method of the inverter, different degrees of harmonic voltage and current occur during operation, so that the motor runs under non-sinusoidal voltage and current. According to the introduction of the material, taking the sine wave PWM inverter that is widely used as an example, its low-order harmonic is fundamentally zero, and the remaining high-order harmonic component that is about twice the carrier frequency is: 2u+1 (u is the modulation ratio). Higher harmonics will cause the addition of stator copper loss, rotor copper (aluminum) consumption, iron loss and additional losses, the most obvious is rotor copper (aluminum) consumption. Because the asynchronous motor rotates at a synchronous speed close to the fundamental frequency, a large rotor loss occurs when the higher harmonic voltage cuts the rotor guide bar with a large slip. In addition to this, additional copper loss due to the skin effect needs to be taken into account. These losses will make the motor rated heat, power decrease, output power decrease, such as the general three-phase asynchronous motor running in the non-sinusoidal power supply of the inverter output, its temperature rise is generally increased by 10%-20%.
2. The dielectric strength of the motor
At present, many small and medium-sized inverters use PWM control methods. His carrier frequency is about several thousand to more than ten thousand kHz, which makes the stator winding of the motor bear a high voltage rise rate, which is equivalent to applying a steep impulse voltage to the motor, so that the inter-turn insulation of the motor can withstand a relatively strict test. In addition, the rectangular chopping impulse voltage generated by the PWM inverter is superimposed on the motor operating voltage, which will pose a threat to the ground insulation of the motor, and the ground insulation will accelerate the aging under the repeated impact of high voltage.
3. Harmonic electromagnetic noise and sensation
Generally, when the asynchronous motor is powered by an inverter, it will make the sensation and noise caused by electromagnetic, mechanical, ventilation and other elements more and more chaotic. The time harmonics contained in the variable frequency power supply and the inherent space harmonics of the electromagnetic part of the motor are interconnected with each other to form various electromagnetic excitation forces. When the frequency of the electromagnetic force wave is the same or close to the natural oscillation frequency of the motor body, the resonance phenomenon will occur, which will increase the noise. Because the motor has a wide operating frequency range and a wide range of speed changes, it is difficult for the frequencies of various electromagnetic force waves to avoid the inherent sensational frequencies of each component of the motor.
4. The adaptability of the motor to frequent start and brake
Because after the inverter is selected for power supply, the motor can be started at a very low frequency and voltage with no impulse current, and can use the various braking methods provided by the inverter for rapid braking, and the conditions for the completion of frequent starting and braking are invented, so the mechanical system and electromagnetic system of the motor are under the effect of cyclic alternating force, which brings fatigue and accelerated aging problems to the mechanical structure and insulation structure.
5. Cooling problems at low speeds
First of all, the impedance of the asynchronous motor is not ambitious, and when the power supply frequency is low, the loss caused by the higher harmonics in the power supply is larger. Secondly, when the speed of the general asynchronous motor decreases, the cooling air volume decreases proportionally to the cubic of the speed, resulting in the deterioration of the low-speed cooling condition of the motor, and the temperature rise increases sharply, making it difficult to complete the constant torque output.
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Reynolds product range models
JJR1000系列：
JJR1011；JJR1017；JJR1022；JJR1030；JJR1037；JJR1045；JJR1055；JJR1075；JJR1090；JJR1115；JJR1132；JJR1160；JJR1200；JJR1250；JJR1 ...
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Operating procedures for Reynolds frequency converters
Bypass cabinet: The cabinet is equipped with high-voltage inlet and outlet isolation switches QS1 and QS2. Among them, QS1 is a single-pole single-throw variable frequency incoming knife switch, and QS2 is a single-pole double-throw power frequency and variable frequency outgoing knife switch. The bypass cabinet is a high-voltage environment, please investigate the status of the live display and electromagnetic lock to ensure safety before ...
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Methods and steps of frequency conversion speed regulation - Reynolds
Frequency conversion speed regulation is to change the power supply frequency through the frequency converter, and then adjust the motor speed to improve the operation efficiency of the electric drive system. Depending on the current, VFDs can be divided into AC-DC-AC type and AC-AC type. At present, the most widely used in China is the AC-DC-AC type.
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Inverter control loop wiring taboo - Reynolds
1. The wires laid out in the inverter control circuit should be separated from the main circuit cable (power line), so as to avoid the harmonic disturbance components on the side of the main circuit of the inverter from polluting the inverter control circuit;
2. Due to the faulty signal of the inverter and ...
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Structural characteristics of Reynolds RHY series inverter governor
1. Technology: (PC or PLC) is used to make the equipment complete the intelligent constant pressure variable supply water supply according to the requirements of water supply and fire protection;
2. High efficiency and energy saving: the system can set the pressure according to the demand, and the system actively adjusts the speed of the pump and the number of pumps according to the set pressure, so that the equipment can run in ...
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Application misunderstandings and drawbacks of inverter and countermeasures - Reynolds
Misunderstanding: connect electromagnetic switches and electromagnetic contactors in the output circuit of the inverter
In actual use, some occasions require the use of contactors for frequency converter switching: such as when the frequency conversion is faulty, switch to the power frequency operation, or when the one-to-two method is adopted, a motor is faulty, and the variable frequency is used.
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The heat dissipation method of the switching power supply
1. Transfer heat pipes for heat dissipation.
In many applications, heat generated from the base steel plate of the power module is transferred through the heat transfer components to the distant surface of the heat pipe. In this way, the temperature of the base steel plate of the power module will be equal to the temperature of the heat pipe heat dissipation surface, the temperature of the heat transfer parts, and the temperature of the two contact ...
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Interpretation of Reynolds inverter models
Take the RNB2000 series inverter as an example.
The model number of the RNB2000 series 37kW inverter is: RNB2037-U
RN: on behalf of Reynolds;
B: low-voltage frequency conversion governor;
2: 2000 series;
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The abnormal installation of the inverter in the power frequency motor leads to hazards
Installing a variable-frequency drive (VFD) on the power frequency motor can complete the precise control and speed regulation of the motor, and improve the power and accuracy of the progressive motor. However, if it is not properly used and used, the following damages may occur:
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The heat dissipation method of Reynolds switching power supply
1. Transfer heat pipes for heat dissipation.
In many applications, the heat generated from the base steel plate of the power module is transferred through the heat transfer components to the distant heat pipe surface. In this way, the temperature of the base steel plate of the power module will be equal to the temperature of the heat pipe heat dissipation surface, the temperature of the heat transfer parts, and the temperature of the two contact ...
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Reynolds inverter manual
Reynolds inverter brochure (partial)
Before installing
When unpacking, it is found that the machine has water or left water traces, indicating that the inverter has been flooded, so please do not install and use it.
When unpacking, it is found that the machine is damaged and deformed or the parts are missing, please do not install and use it, otherwise there will be fault expansion and personnel ...
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Difference Between Soft Starter and Inverter – Reynolds
Soft starters and frequency converters are two completely different products. The inverter is used in the local area where speed regulation is required, and its output not only changes the voltage but also changes the frequency at the same time; A soft starter is actually a voltage regulator, which is used when starting a motor, and the output only changes the voltage and does not change the frequency. Change...
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Precautions for installation of Reynolds low-voltage inverters
One. Safety Precautions
1. First of all, it is necessary to have certain electrical professional knowledge, and understand the job site, understand the equipment status, and have certain electrical operation technology.
2. Determine the voltage level of the equipment (such as low-voltage AC380V) and whether it is low-voltage ...
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Common faults and solutions of vector inverter - Reynolds
The following faults may be encountered during the use of the inverter, please refer to the following methods for simple fault analysis:
1. No manifestation at power-on:
1) Use a multimeter to check whether the input power supply of the inverter is consistent with the rated voltage of the inverter, and check the cleaning problem.
2） ...
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Inverter breakdown factor – Reynolds
1. Overpressure leads to brake pipe breakdown.
The so-called overvoltage of the inverter refers to the fact that the inverter voltage composed of various reasons exceeds the additional voltage, which is reflected in the DC voltage of the inverter DC bus.
Overvoltage alarm generally appears when the machine is shut down, and its main ...
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The difference between overload and overheating of the inverter – Reynolds
The inverter is an electric control equipment that uses frequency conversion technology and microelectronic technology to control and communicate the motor by changing the power supply frequency of the motor operation. The inverter is mainly composed of rectifier (AC to DC), filtering, inverter (DC to communication), braking unit, drive unit, detection unit ...
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Protection function of the Reynolds soft starter
1. Overload protection function: The soft starter introduces a current control loop, so that the change of motor current can be tracked and detected at any time. By increasing the setting of overload current and the anti-time control mode, the overload protection function is realized, so that when the motor is overloaded, the thyristor is turned off and an alarm signal is issued.
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The Reynolds SVG series was successfully completed
More than 40 sets of RNSVG series low-voltage power generator sets and RNZB series high-voltage reactive power automatic compensation devices designed and produced by Reynolds have been successfully completed and will be delivered in the near future.
This product is owned by Shanghai Reynolds ...
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Reynolds inverter control method
The actuator commonly used in the industrial field of Reynolds inverter has good speed regulation performance and simple and convenient operation method. Therefore, it is widely used in the automation system.
Typical wiring method for the main circuit of a Reynolds frequency converter
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Misunderstanding of inverter control loop wiring - Reynolds
1. The wires of the inverter control circuit should be strictly distinguished from the main circuit cable (power line) and placed separately. This effectively prevents the inverter's control circuit from being disturbed by harmonics in the inverter's main circuit.
2. To separate the connection of the inverter from the terminals or contacts of other control circuits, ...
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