Some Considerations for Using Variable Frequency Drive
VFD should not be installed on vibrating equipment, because the main circuit connection screw in the VFD is easy to loosen under this condition, many variable frequency drives are thereof damaged.
Wiring connection: an air switch had better to be installed at the output end of VFD, so as to prevent the VFD from being seriously burned in case of short circuit. The N end must not be grounded. The control line should not be too long, because the control board is vulnerable to electromagnetic interference and cause misoperation, which will also lead to the damage of the control board. Shielding wire shall be used if the control line is longer than 2m. Contactor with high current and frequent operation shall not be installed beside the converter, because it causes great interference to the VFD and makes the VFD to act incorrectly.
VFDs required for quick stop had better not to brake by itself, an additional braking unit or mechanical brake can be added, otherwise the VFD would often impacted by motor back, and the failure rate will be greatly improved.
If the variable frequency drive often operates at low speed below 15 Hz, the motor should be equipped with additional cooling fan.
Dust and humidity are the most lethal killers of VFDs. It is better to install the VFD in the air-conditioning room or in the cabinet with dust net. Clean the dust on the circuit board and radiator regularly. If the variable frequency drive has stopped for a period of time, better to blow the circuit board with a hairdryer before it is energized.
VFD will send out overheating protection when its cooling fan is broken, replace the fan when there’s a noise.
Some factories use the generator to supply electricity, the voltage is unstable and VFD is often damaged. Good effects are obtained after the generator is equipped with voltage stabilization or over-voltage protection device.
Lightning protection is also important. It happens rarely, but when the VFD is struck by lightning, it will be badly damaged. The VFD for constant pressure water supply is most susceptible to lightning strikes because it has a detonator pipe extending into the sky.
To avoid electromagnetic interference, shielding line shall be used for input and output control lines of VFD. The shielding line shall not be wrongly connected, otherwise opposite effects would be achieved. It may also be protected with a steel pipe or equipped with a wave filter, so as to reduce the carrier frequency. We find that if the switch pipe of converter’s switching power supply is a field effect transistor, its interference will be greater.
Once the VFD is broken, don't repair it at inexperienced personnel! Based on our experience, the modules may be faulted in case of fast fuse, but if the module is broken, the fast fuse is not necessarily broken. The power module and rectifier module of many converters are interchangeable.
Wiring connection: an air switch had better to be installed at the output end of VFD, so as to prevent the VFD from being seriously burned in case of short circuit. The N end must not be grounded. The control line should not be too long, because the control board is vulnerable to electromagnetic interference and cause misoperation, which will also lead to the damage of the control board. Shielding wire shall be used if the control line is longer than 2m. Contactor with high current and frequent operation shall not be installed beside the converter, because it causes great interference to the VFD and makes the VFD to act incorrectly.
VFDs required for quick stop had better not to brake by itself, an additional braking unit or mechanical brake can be added, otherwise the VFD would often impacted by motor back, and the failure rate will be greatly improved.
If the variable frequency drive often operates at low speed below 15 Hz, the motor should be equipped with additional cooling fan.
Dust and humidity are the most lethal killers of VFDs. It is better to install the VFD in the air-conditioning room or in the cabinet with dust net. Clean the dust on the circuit board and radiator regularly. If the variable frequency drive has stopped for a period of time, better to blow the circuit board with a hairdryer before it is energized.
VFD will send out overheating protection when its cooling fan is broken, replace the fan when there’s a noise.
Some factories use the generator to supply electricity, the voltage is unstable and VFD is often damaged. Good effects are obtained after the generator is equipped with voltage stabilization or over-voltage protection device.
Lightning protection is also important. It happens rarely, but when the VFD is struck by lightning, it will be badly damaged. The VFD for constant pressure water supply is most susceptible to lightning strikes because it has a detonator pipe extending into the sky.
Once the VFD is broken, don't repair it at inexperienced personnel! Based on our experience, the modules may be faulted in case of fast fuse, but if the module is broken, the fast fuse is not necessarily broken. The power module and rectifier module of many converters are interchangeable.
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