OEM Accepted AC Motor Drives variable frequency inverter 280kw For Fan

VFD design artical

As the power terminals will be mounted on a power pcb, easily accessible, and will be robust enough for the size of cable.

The terminals on the control board will be smaller, as these generally handle lower voltages and currents. Variable frequency drives usually have a variety of control and monitor connections, such as programmable digital inputs, analog inputs, analog outputs and relay connections. The digital inputs can start and stop the VFD, reverse the motor direction, select fixed frequencies etc. The analog inputs can be used to control the motor speed, or may be connected to sensor when the variable frequency drive is operating in closed loop control mode. Analog outputs and relays may be used to indicate a fault, as well as ‘running’, ‘speed reached’ etc. All these connections can be programmed to suit the user. Most variable frequency drives will also have some form of serial interface such as Modbus or Canbus to allow control and monitoring in a larger system. This may be via a separate connector such as an RJ45.

At the front of the variable frequency drive there should be some buttons and a simple display to set up or control it, although on some VFDs this is an option. The display may consist of simple seven segment LEDs, or a full text display which carries more information in many languages. All these control connections, buttons and displays, are mounted on the main control board.

All this needs to be packaged. For smaller variable frequency drives, a simple plastic box, cunningly fitting around the terminals, pcbs etc. is the solution. For larger VFDs, a substantial steel casing and covers (with terminal access) is needed.

If the variable frequency drive is mounted in a cubicle or machine, an IP20 case may be suitable. However, if the unit is mounted on the wall in a plant or process area, a higher level of protection is better, such as IP55 or greater. Many - but by no means all - VFD suppliers will offer these options. This is an important consideration as many variable frequency drives fail as a result of contamination of the electronics by dirt or liquids.

FPR500A Product specifications