There are both physical and electrical installation basics to be aware of when using a VFD. When mounting the VFD on a back panel, be sure to check the specifications. It is common for multiple devices to be installed in one location, but all VFDs need proper air flow, so check the installation instructions carefully when laying out a control panel. Mount the drives vertically.
- Electrically, proper run/stop control of the VFD is important. Many manufacturers do not recommend using contactors or disconnect switches on the line or load side of a VFD for run/stop control of the ac drive and motor, except for emergency situations. Opening a contactor at the line or load side of a VFD while the motor is running can cause failures in the inverter section of the drive or reduce its life.
- With any motor control circuit, proper overcurrent and ground-fault protection is required at the input of the device. A normal VFD takes single-phase voltage, but it isn’t planned for usage with single-phase motors. Although a standard three-phase induction motor works with a VFD, a three-phase inverter duty motor should be used.
- There are many more factors, features and functions to consider when using a VFD, so study the catalogs and manuals and then get with your vendors. With constant-speed or constant-torque applications, like compressors, conveyors or mixers, there might be easier possibilities. However, whether replacing a dc motor or varying the speed and acceleration of your conveyor, fan, blower or pump, go with the VFD option. It’s often the best choice, if installed properly.
- Cooling: VFD control units must be placed in positions where the highest ambient temperature doesn’t surpass 40˚C. This is a common temperature rating for most units. If higher ambient are expected, derating of the variable frequency drive may be required.
- Supply line power quality: The supply to the VFD input mustn’t change minus or plus ten percent as most VFDs will trip through a protective error. This voltage steadiness must be taken into consideration while operating conductors to the VFD and voltage drops must be found out for long runs.
- Electrical connections: The installation and sizing of VFD load and line conductors must obey the NEC or similar appropriate local codes.
- Grounding: For dependable and safe functioning, all VFDs should be correctly grounded. This usually demands for a grounding conductor to be taken back to a single point grounding position, generally chosen to be at the service. Along with that, a grounding conductor should also be carried back from the motor to the VFD’s inner grounding terminal.
- Fault protection: Numerous VFD have short-circuited shield, in the form of fuses, previously fit by the manufacturer. This is usually the case on larger hp units. Minor units need external fuse shielding. In any of these case, the sixing and choice of these fuses is vital for shielding a semiconductor in the event of an error.
- Motor protection: All motors require overload protection. The utmost customary practice is the utilization of a motor overcurrent relay system that would shield all 3 phases and shield in contradiction of single-phasing.
- Humidity and moisture: in both electrical and electronic equipment, large corrosive atmospheres and humidity are worrisome. VFD units must be mounted in a non-corrosive position at any time, with ambient humidity ranging between zero to ninety five percent noncondensing.
Precautions While Installing VFD are:
- Do add a line reactor when line power source is more than 10 times the kV-A rating of the drive.
- Use different conduit for output power, input power and control wiring. More particularly, when linking the VFD’s control wiring and power, the following guidelines should be followed:
- Install the input ac power wiring in its own rigid steel conduit.
- Install the output motor wiring in its own rigid steel conduit.
- In its own stiff steel pipe, mount the control wiring. Low voltage dc control wiring and one-hundred-and-twenty-volt ac control wiring must be in different conduits. Both twisted pair and shielded wire are sufficient when wiring to the VFD’s control board. Two and three-wire connections are recommended. For many drives, the minimum wire size is 18 AWG.
- Make sure that all ground connections are fitted and grounded properly. The shield must be attached to ground at only 1 end of the cable to prevent ground loops. When connecting the shield at the VFD end, connect it to the chassis ground lug.
- Separate control and feedback wiring from power wiring by at least 12 inches.
- In installations with multiple VFDs, input power wiring for all VFDs can be in the same conduit, and the control wiring can be in the same conduit, but the output wiring for each motor must be in a separate conduit. The only exemption is that if 1 VFD is utilised to control multiple motors, the end wiring for all the motors can be in the same conduit.
- Use the drive on a grounded system. Never use a floating ground. Few manufacturers don’t suggest working with a detached input on any newly created drives. If there are no interruptions on the line, the drive should function properly, but critical common-mode error can lead to nuisance tripping or other serious issues.
- Don’t insert a contactor amid the motor and the drive
- If the contactor is absolutely necessary, an early-break auxiliary set of contacts on the device should be interlocked with the VFD’s external fault input or stop input.
- Don’t rotate the input power farther than once every 2 minutes
- Do not use a ground-fault circuit interrupter (GFCI) if the drive is equipped with a filter.
How is VFD Panel Installation and Commissioning Performed?
The process of setting up the parameters of the drive adds additional time for commissioning and installation, and is most easily completed by copy/paste tools which have many positive functions such as:
- The ability to copy the parameter set from one drive to the next
- Able to store parameters to maintain the parameter set for a different application configuration
- Can be used to easily replace downed or failed drives
These tools can easily decrease how complex the processes of installation, commissioning, and troubleshooting may become.
- VFDs are fitted at Fan Pump motors.
- Fan pump motor is liable for providing stock to the Head Box
- Head Box requires a control of either head or level
- Control of a level or pressure in Head Box is done by VFITD
A signal is fed to the VFD and with the help of a comparator, an signal is created depending on the shifting of present value from the recommended value. The controller in the VFD, then, increases/ decreases the speed based on the signals generated
Input AC Power
- Circuit breakers feeding the VFDs are recommended to be thermal-magnetic and fast acting.
- They should be sized as 1.5 times the input amperage of the drive. Refer to the table below.
- Each VFD should be fed by its own breaker. If numerous drives are to be united on the same breaker, every drive must have its own protection measure from the breaker.
- Input AC line must be ran through pipe from the breaker panel to the drives. Using a single conduit, AC input power to several VFDs can be driven, if necessary.
- The VFD should be grounded on the terminal marked PE.
- Motor wires from every VFD to its individual motor should be ran through a different steel conduit far from incoming AC power wiring and control wiring to prevent crosstalk and noise between drives.
- If the gap among the VFD and the motor exceeds two hundred and fifty feet, an output reactor must be utilised amid the VFD and the motor. The sizing of output reactor must be done accordingly.
- If the distance between the VFD and the motor is between 500 and 1000 FT, a dV/dT filter should be used.
- No contactor must be fit amid the motor and the drive. Functioning such kind of a device at the same time when the drive is working can cause harm to the power components of the drive.
- When a detach switch is fit amid the motor and the drive, it must only be activated when the drive is in a STOP stage.
An example of programing is given below:
The Drive should be programmed for the proper motor voltage.
- The Drive should be programmed for the proper motor overload value
- To enter the PROGRAM mode to access the parameters:
- Press the Mode (M) button. This will activate the password prompt (PASS).
- Use the Up and Down buttons to scroll to the password value and press the Mode (M) button. After entering the right password, the display will show that the PROGRAM mode has been opened or assessed at the starting of the parameter menu.
- Use the Up and Down buttons to scroll to the desired parameter number.
- After the wanted parameter is located, press the Mode (M) button to exhibit the current parameter adjustments. The parameter value will start blinking, denoting that the current parameter adjustments are being shown. The value of the parameter can be changed by using the Up and Down buttons.
- To store the new setting and also exit the PROGRAM mode, press the Mode (M).