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Noise radiated from a frequency inverter cable is proportional to the amount of varying electric current within it. As cable lengths grow, so does the magnitude of reflected voltage. This transient over voltage, combined with the high amplitudes of current associated with frequency inverters, creates a significant source of radiated noise. By shielding the frequency inverter cable, the noise can be controlled. In the tests presented in this paper, relative shielding effectiveness was observed by noting the magnitude of noise coupled to 10 ft. of parallel unshielded instrumentation cable for each frequency inverter cable type examined. The results of the shielding effectiveness testing are documented in the Figure.
As demonstrated by its trace in that figure, foil shields are simply not robust enough to capture the volume of noise generated by frequency inverters. Unshielded cables connected between a frequency inverter and a motor can radiate noise in excess of 80V to unshielded communication wires/ cables, and in excess of 10V to shielded instrumentation cables. Moreover, the use of unshielded cables in conduits should be limited, as the conduit is an uncontrolled path to ground for the noise it captures. Any equipment in the vicinity of the conduit or conduit hangers may be subject to an injection of this captured, common- mode noise. Therefore, unshielded cables in conduit are also not a recommended method for connecting frequency inverters to motors.
As demonstrated by its trace in that figure, foil shields are simply not robust enough to capture the volume of noise generated by frequency inverters. Unshielded cables connected between a frequency inverter and a motor can radiate noise in excess of 80V to unshielded communication wires/ cables, and in excess of 10V to shielded instrumentation cables. Moreover, the use of unshielded cables in conduits should be limited, as the conduit is an uncontrolled path to ground for the noise it captures. Any equipment in the vicinity of the conduit or conduit hangers may be subject to an injection of this captured, common- mode noise. Therefore, unshielded cables in conduit are also not a recommended method for connecting frequency inverters to motors.
I have an application that require running an 55Kw high efficiency induction motor at rated torque at any rpm from 5% to 100% of the rated rpm. It will be controlled by a frequency inverter with FOC.
This motor has independent cooling fan running with a separate motor that is capable of removing 5Kw heat from the motor. It will be controlled by an inverter with FOC. The motor is a good 95% efficient with cast copper rotor / not the regular cast aluminum. Can an induction motor give out full torque at 5% of its rated rpm with an inverter?? My concern is it may over heat at low frequency - not due to cooling fan because that is independent, but due to the other reasons.
This motor has independent cooling fan running with a separate motor that is capable of removing 5Kw heat from the motor. It will be controlled by an inverter with FOC. The motor is a good 95% efficient with cast copper rotor / not the regular cast aluminum. Can an induction motor give out full torque at 5% of its rated rpm with an inverter?? My concern is it may over heat at low frequency - not due to cooling fan because that is independent, but due to the other reasons.
Electrical environment
A. Prevent overvoltage in input terminal
The main circuit of the inverter is consisted of power electronic parts, these devices are very sensitive on the voltage, the over voltage on input terminal will cause permanent damage of the main components. For example, some factories have their own electricity generator, power grid fluctuation is relative high, so they should have precautions on the input voltage of the frequency inverter.
B. Prevent electromagnetic interference
The inverter main electrical components are power module and control system hardware and software circuit, If these components and software programs are impacted by a certain electromagnetic interference, it will cause hardware circuit malfunction, software program failed and then cause accident. So, in order to avoid electromagnetic interference, the variable frequency inverter needs to prevent electromagnetic interference according the electrical environment. For example: the input power cord, output motor lines, control lines shall be kept away from each other; The devices and signal lines which are easily affected, should be installed as far as possible from the frequency inverter; The critical signal lines should be shielded cable, it is recommended to use shield cable with 360° grounded.
A. Prevent overvoltage in input terminal
The main circuit of the inverter is consisted of power electronic parts, these devices are very sensitive on the voltage, the over voltage on input terminal will cause permanent damage of the main components. For example, some factories have their own electricity generator, power grid fluctuation is relative high, so they should have precautions on the input voltage of the frequency inverter.
B. Prevent electromagnetic interference
The inverter main electrical components are power module and control system hardware and software circuit, If these components and software programs are impacted by a certain electromagnetic interference, it will cause hardware circuit malfunction, software program failed and then cause accident. So, in order to avoid electromagnetic interference, the variable frequency inverter needs to prevent electromagnetic interference according the electrical environment. For example: the input power cord, output motor lines, control lines shall be kept away from each other; The devices and signal lines which are easily affected, should be installed as far as possible from the frequency inverter; The critical signal lines should be shielded cable, it is recommended to use shield cable with 360° grounded.
There are local start/stop and remote start/stop, function set,
parameter set, fault inquiry, operation record on WINDOWS interface.
Set inverter parameters by colorful LED touch-screen. Output operation data table can be printed out. HMI can display voltage/ current waveform, frequency, speed and motor status at any time.
Good ability in detecting and indicating: operation status of every part of inverter can be detected. Integrated fault monitor circuit, accurate fault orientation, fault position and type showing in HMI make fault points clear at a glance. Easy replacement of broken cell reduces MTTR and can be operated by general personnel.
Set inverter parameters by colorful LED touch-screen. Output operation data table can be printed out. HMI can display voltage/ current waveform, frequency, speed and motor status at any time.
Good ability in detecting and indicating: operation status of every part of inverter can be detected. Integrated fault monitor circuit, accurate fault orientation, fault position and type showing in HMI make fault points clear at a glance. Easy replacement of broken cell reduces MTTR and can be operated by general personnel.