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    How to choose the right AC drive

    2024-08-08 11:38:58

    How to choose the right AC drive

     

    Having more choices is not always a good thing. Take AC frequency converter as an example: In the past, only a few companies produced AC frequency converters, and they were mainly used for basic motor speed control. There are hundreds of brands, multiple types, and a wealth of communication and control options, all of which may confuse you.

     

    Know your motor

    Checking the nameplate on the motor is the first step in specifying the correct inverter drive. Most AC motors have a nameplate that will indicate the power supply voltage, kilowatts or power, and amperage. To convert horsepower to kilowatts, simply multiply horsepower by 0.75. Make a note of this information, as it is very important to specify the correct drive. Note that you will need a DC drive for DC motors.

     

    There may be a lot of information on the motor nameplate, so if you are not sure what you are looking for, please take a picture of the nameplate and email it to us.

     

    Understand your requirements

    This seems to be an obvious problem, but understanding your requirements is the key to ensuring that you don't have to pay too much for the inverter drive. Most modern variable speed drives have heavy load and normal load ratings. These are commonly referred to as variable torque (ND) or constant torque (HD) applications. Fundamentally, constant torque is like driving on a highway, and your speed remains stable for hours. Variable torque is like driving in a city that is constantly stopped and started. Applications such as fans and pumps usually work normally because they will slowly accelerate and then run for several hours. Things like conveyor belts and compressors are heavy because they can be started and stopped, and the load changes many times per hour.

    Consider the environment

    Take a moment to consider where the variable speed drive is installed. If the environment is corrosive or very humid, then the wise choice is to install the inverter driver in the panel or buy a driver with a higher IP rating. IP stands for Ingress Protection, usually a two-digit number. The higher the level, the higher the protection. Variable speed drives affected by flushing procedures or extreme conditions must be sealed to at least IP65 or IP67.

     

    Control your drive

    Consider how to control the speed of the inverter. Do you plan to use the keyboard, potentiometer or PLC to control the speed of the AC drive? If the variable speed drive is not easily accessible (ie, inside the panel), you may want to consider using a remote keyboard or PLC.

     

    Determine your inverter I/O requirements

    Your new inverter drive will need to interact with other equipment in the factory. Therefore, it is important to know how many inputs and outputs and the types of inputs and outputs you will need.

     

    The digital input is used to connect the inverter drive with PLC, switches, buttons and other equipment. These signals can be used for start/stop, forward/reverse, external fault, preset speed selection and other functions.

     

    On the other hand, the analog input allows the driver to be controlled by a simple 0-10VDC or 4-20 mA signal. This can be as simple as a jar, or it can be feedback from a PID controller.

     

    The PTK input can be used to monitor simple temperature sensors in the motor windings to avoid damage under overload conditions.

     

    Digital and relay outputs are useful when you want to notify the external device of the status of the external device, for example, if a fault occurs or the set speed is reached.

     

    Communication requirements

    Profibus, Modbus, Ethernet, CanBus...the list of available communication options is endless. Fortunately, most modern frequency converter drives (such as Yaskawa A1000 and Control Techniques Unidrive SP) have plug-in expansion modules that can access most communication protocols.

     

    Programming

    Programming a VSD can be a daunting task. Unfortunately, too many manufacturers focus on high-end applications and make simple application programming much more difficult than originally needed. It is estimated that 60% of operators use only the first 7 parameters. For simple applications, we recommend the Control Techniques M200 or Danfoss Micro Drive series, which are very easy to set up and have pre-loaded parameters for standard tasks. For more complex tasks, we recommend using Control Techniques M700 or Danfoss VLT AutomationDrive, which are also easy to install, but provide more functions than simple M200 and Micro Drive AC drives.

     

    All variable speed drives need a filter to avoid transmitting electrical noise back to the power supply. Some frequency converter drives come standard with integrated industrial filters, while other frequency converters have no internal filters at all. Which method is more suitable for you depends on how the drive is installed. For example, if you install multiple drives in one panel, a drive without a filter can save costs because you can use one filter to provide all drives. If you want to install the drive in a residential or commercial environment, such as an escalator in a shopping mall, you need a commercial filter.

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