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  • Can ordinary motor achieve frequency control?
    Ordinary motor can realize variable frequency control. However, it is not recommended to use low frequency (below 30HZ) for a long period of time.
  • What does the protection level of inverter mean?
    The protection level of the frequency converter is generally IP20 (the protection level of CHV110 is IP54). 

    IP (INTERNATIONAL PROTECTION) PROTECTION grade system is drafted by IEC (INTERNATIONAL ELECTROTECHNICALCOMMISSION). The electric appliance is classified according to the characteristics of dust and moisture proof. The IP protection level is composed of two Numbers. The first number represents the level of the electrical appliances from the dust and prevents the invasion of foreign objects, namely the protection of foreign solid objects. The second digit indicates the density of the electrical protection against moisture and waterproofing intrusion. The larger the number indicates the higher the protection level, the better the protection of water. 

    The level of protection indicated by two signs is shown below. 

    The first number

    Protection level
    0 No protection
    No special protection for surrounding human对beings or objects
    Prevent the solid object with more than 50mm diameter from intruding
    Prevent the human body (such as palm) from accidental contact with the interior of the electrical parts, preventing foreign objects (diameter greater than 50mm) from intruding.
    2 Prevent the solid object with more than 12mm diameter from intruding
    Prevent the human body (such as palm) from accidental contact with the interior of the electrical parts, preventing foreign objects (diameter greater than 12mm) from intruding.
    Prevent the solid object with more than 2.5mm diameter from intruding
    Prevent a tool or wire or similar objects with diameter or thickness greater than 2.5mm from intruding and touching the parts inside the appliance.
    Prevent the solid object with more than 1.0mm diameter from intruding
    Prevent a tool or wire or similar objects with diameter or thickness greater than 1.0mm from intruding and touching the parts inside the appliance.
    5 Dust proof
    Completely prevent the invasion of foreign objects, although it cannot completely prevent dust from entering, but the amount of the dust does not affect the normal work of the appliance.
    Dust proof
    Completely prevent the invasion of foreign objects and dust
    The second number
    Protection level 
    0 No protection
    No protection
    1 Prevent waterdrop from intruding
    Prevent waterdopr from dripping vertically (eg condensation water), thus avoiding harmful impact on the appliance.
    2 Tilt 15 degrees can still prevent waterdrops from intruding
    When the appliance is tilted vertically to 15 degrees, the drip will not produce harmful effects to the electric appliance
    3 Prevent the spraying water from instruding
    Rain proof or prevent spraying water from entering the appliance and cause damage.
    4 Prevent splashed water from intruding
    Prevent splashed water from entering the applicance and cause damage.
    5 Prevent ejected water from intruding
    Prevent ejected water from intruding the appliance and cause damage.
    6 Prevent water wave from intruding
    Appliance installed on the deck to prevent intrusion of water wave.
    7 Prevent water
    Prevent water from intruding the appliance and cause damage.
    8 Prevent water during sinkage
    Prevent water from intruding during sinkage

  • Why is there leakage current problem?
    When the inverter is not used, the leakage current is generally small. When using the inverter, as the power module of the inverter is high speed switch, the output current has the existence of high harmonics. There is a sense of inductance between the cable and the ground and the cable, resulting in a large leakage current (which can be up to 10 times less than the frequency inverter). 
  • What are the requirements for heat dissipation space and air conditioners installed by inverter?
    According to the inverter power consumption of 4%, the airtight space has several air conditioners, high-power machines, low-voltage low-power self-equipped fans to maintain good ventilation.
  • Is it OK to direct the motor to a fixed inverter without soft starting?
    No, the inverter with fixed frequency has output voltage, and the motor input has a large current, which causes the protection of inverter.
  • Is there any limit to the direction of the installation of inverters?
    The inverter can be installed on the wall or in a cabinet, so as not to reduce the heat dissipation effect of the inverter, please install it vertically.
  • What is variable frequency reAnswer? What's the meaning?
    For a digital control inverter, even if the frequency command is ananalog signal, the output frequency is also given reference level. The smallestunit of this differential is known as the frequency conversion reAnswer. Thefrequency reAnswer is usually 0.015~0.5Hz. For example, the reAnswer is 0.5 Hz,so the top of 23Hz can be changed to 23.5 and 24.0 Hz, so the motor's action isalso followed by the level. This creates problems for the use of continuousvolume control. In this case, if the reAnswer is 0.015 Hz, the level of grade 4motor is 1r/min, and it can be fully adjusted. In addition, the given reAnswerand output reAnswer are not the same.
  • What is regenerative braking?
    When the motor is in operation, if the instruction frequency is decreased, then the motor becomes an asynchronous generator state and works as a brake, which is called regenerative (electrical) braking.
  • What does the stall prevent function mean?
     If the given acceleration time is too short, the output of theinverter frequency changes more than speed change of the angular frequency (electricity),the inverter will trip due to flowing through the overcurrent, and operationwill stop, this is called stall. To prevent the motor from running, check thefrequency control of the current. Speed up when the acceleration current is toolarge. The same is true with deceleration. The combination of the two is thestall function. 
  • Can the speed accuracy be improved if the motor with PG is used?
    The inverter with PG feedback can improve the accuracy. However, the value of the speed precision depends on the accuracy of the PG itself and the frequency of the inverter output.
  • What to do when the actual speed is biased against a given speed?
     During open loop, the inverter can change the speed of the motor atthe range of rated slip (1% ~ 5%) even when the motor is running with load. Forthe requirement of high speed regulation accuracy, even if the load change isrequired to operate at a given speed, the inverter with PG feedback can beused.
  • What is PID adjustment?
    In engineering practice, themost widely used regulator control law is proportional, integral, differentialcontrol, or PID control, and PID control. Theparameter setting of PID controller is the core content of control systemdesign. It is based on the characteristics of the controlled process to determinethe ratio of PID controller, the integral time and the size of the differentialtime. There are many methods of PID controller parameter setting, and thecritical ratio method is generally adopted. The whole procedure of PIDcontroller parameters by using this method is as follows: (1)First select a sampling cycle short enough to let the system work (2)Only add the proportional control link, until the system has a criticaloscillation of the input step response, and record the proportional amplificationcoefficient and the critical oscillation period (3) The parameters of PID controller are calculated byformula under certain degree of control.
  • What does open-loop mean?
    The electrical device used to set speed detector (PG) to feedback the actual speed to control device, such process is known as the "closed loop", the one needs no PG operation is called "open loop". General inverter is mostly open-loop, some models also use optionals for PG feedback. Speed sensorless closed-loop control method is based on the established mathematical model according to the actual flux of the motor speed, the equivalent of with a virtual speed sensor to form closed-loop control.
  • How does the torque change in the motor when changing V and f proportionately?
    The decrease in frequency is completely in proportional to the lower voltage, so the DC resistance will not change due to the reduced AC impedance, which will result in the decrease of the torque at low speed. Therefore, when given V/f at low frequency, the output voltage should be improved so as to obtain a certain starting torque, which is called enhanced starting.
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