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Start mode settingNormal start
At normal start status, inverter will start and operate at given frequency in open loop mode, or operate at the expected value of the controlled object in closed loop mode.
Soft start
At soft start status, inverter will start and accelerate to the frequency of power grid regardless of the given frequency. When the output frequency of inverter reaches the frequency of power grid (set in main interface), then the output of inverter will become 0, at the same time inverter sends 'transfer to power grid' command. This command can make the control circuit to transfer the power supply of the motor from inverter to the power grid. During the transient transfer, there is a big inrush current.
For synchronous transfer (OPTIONAL FUNCTION, synchronous transfer reactor is required), both inverter and power grid will supply the power to the motor during the transient transfer, there is very small inrush current.
Operation mode setting
closed loop
In closed loop mode, frequency inverter will automatically adjust the output frequency and operate at the expected value of the controlled object. User can set the expected value of the controlled object, such as pressure, temperature.
open loop
In open loop mode, inverter will operate at given frequency. The given frequency can be set in main interface, external analog signal, or the data bus in the field.
Waveform display
By sampling the input/output current/voltage, to show the waveform and calculate the power factor and input/output power.
Automatic schedule
User can fill out the schedule timetable for a period of time. inverter will operate automatically at the exact value given in the schedule timetable at the setting time.
Operation log
frequency inverter Operation log can be recorded automatically. Every operation and the accurate time of the operation will be recorded.
Operation record
The parameters recorded include given frequency, motor speed, input current, output current, input voltage, output voltage, the value of controlled object and system status. All parameters recorded will be automatically saved daily in flash memory of the embedded computer integrated with HMI as a txt file. The name of the txt file is the date. The “Record Interval” can be set by the user.
Function lock setting
By setting the local/remote control function lock, the schedule mode, given mode, start mode and operation mode in local/remote control. In local/remote control mode, inverter will run automatically according to the mode selected by the function lock selected.
Motor protection setting
For the special requirement of overload and under-load protection, the user can change the default
value of the protection in this interface.
Bypass function
QF is existing breaker of the user.
If QS1, QS2, QS3 are offline isolator switches, inverter can only be bypassed manually when QF is open.
QS1 and QS2 are close, QS3 is open, the motor is driven by frequency inverter.
QS1 and QS2 are open, QS3 is close, the motor operates in DOL (direct on line) mode. inverter is isolated from the power grid and the maintenance can be done.
If all QS1, QS2 and QS3 are vacuum contactors or breakers, frequency inverter can be bypassed automatically. For soft start or synchronous transfer, all QS1, QS2 and QS3 must be vacuum contactors or breakers.
When bypassing inverter for synchronous motor, the excitation current control from inverter will be transferred to original control mode.
Additional function
valve-link
Close/open of the valve can be automatically controlled by frequency inverter.
Frequency setting
Given frequency can be set by the computer or by external analog signal.
Computer Given
Set the frequency by the acceleration or deceleration button in the main interface or by ‘Given-frequency’ button.
Analog Given
Accept 0~10V or 4~20mA external analog signal as the given frequency.
Control mode setting (Local/remote control)
Local control
Control inverter through touch screen interface and buttons on the inverter panel.
Upper PC control ( OPTIONAL FUNCTION)
The user can operate frequency inverter by the upper PC, i.e. start, stop, emergency stop, reset, setting frequency and browse the log. The user can monitor all the key operating parameters of inverter by the upper PC, i.e. current, voltage, frequency, the actual value of controlled object and alarms. One upper PC can monitor 32 inverters at the same time.
DCS control
Programmable digital and analog port can be connected to DCS directly by hard cables or by data bus cables through communication protocol (Modbus, Profibus, TCP/IP, DeviceNet, etc).
GPRS remote control ( OPTIONAL FUNCTION)
User can control and monitor inverter in another place via GPRS wireless network.
Parameter setting
All parameters can be made a backup.
Set two frequency-skipping segments to reduces the possible resonance, such as fan resonance.
Set the torque booster for starting different loads.
Set the over-current and over-load protection as per different requirement.
Extendable for the motor control parameters.
Failure self-diagnosis and record
inverter can self-diagnose and record the failure. For light failure, alarm message is displayed in main interface in real time; for serious failure, failure interface and the fault location is automatically displayed.
The user can check the past failures from the failure interface.
System configuration
Multi-level voltage source frequency inverter with the technology of cascade-connected power cells can directly output medium voltage, i.e. 3kV, 3.3kV, 4.16kV, 6kV, 6.6kV, 10kV and 11kV. inverter is composed of phase-shifting transformer, power cells and controller.
3kV series inverter
There are 12 power cells for 3kV series and every 4 power cells constitute a phase. Three phases are 'star' connected and supply the power to the motor directly.
3.3kV series inverter
There are 12 power cells for 3.3kV series and every 4 power cells constitute a phase.
4.16kV series inverter
There are 15 power cells for 4.16kV series and every 5 power cells constitute a phase.
6kV series inverter
There are 15 power cells for 6kV series and every 5 power cells constitute a phase.
6.6kV series inverter
There are 18 power cells for 6.6kV series and every 6 power cells constitute a phase.
10kV series inverter
There are 24 power cells for 10kV series and every 8 power cells constitute a phase.
11kV series inverter
There are 27 power cells for 11kV series and every 9 power cells constitute a phase.
Configuration of power cell
It is a basic single phase AC-DC-AC inverter circuit. The rectifier is a three-phase diode bridge. By controlling the IGBT inverter in sine wave PWM, get single phase AC output.
Each power cell is completely identical in structure, and can be replaced with another.
Configuration of input side
Phase-shifting transformer supplies the power to power cells. The secondary windings of the transformer are divided into three groups. Based on the number of the cells per phase, the rectifier mode of multi-level phase-shifting overlap includes 24-pulse, 30-pulse, 36-pulse, 48-pulse or 54-pulse, which greatly improves the current waveform of the power grid (The THD of voltage and current in the power grid side can directly satisfy IEEE519 harmonics standard), and the input power factor is near 1, no harmonic filter and power factor correction capacitor required.
In addition, the independent secondary windings of the phase-shifting transformer isolate electrically the power cell from another. The power cell is similar to low voltage PWM frequency inverter. Many inverters are connected in series to form step PWM sine wave. This PWM technology is mature and well proven.
Configuration of output side
U and V output of each power cell are connected in series to form a star connection to supply the power to the motor. By restructuring PWM waveform of each cell, we can get the step sine PWM waveform. It has a good sine-shape, small dv/dt, the long motor cable is available without output filter . Meanwhile the output harmonic is very less, which greatly reduces mechanical vibration and mechanical stress of the bearings and the vanes.
[OPTIONAL FUNCTION] When one power cell is in failure, the system will automatically bypass the faulty cell. All other cells will continue to work and keep the same output line voltage to the motor. The inverter will continue to run but in de-rating mode without the trip-off and the motor will continue to work without any stop. The production loss caused by accidental shut-down of the motor can be avoided in many cases.
Controller
Controller is composed of high speed SCM, HMI and PLC. SCM realizes PWM control. HMI based on Windows CE is friendly touch screen interface. Embedded PLC treats with the logic of digital signals and communicates with the controller system of the user with great flexibility.
Controller communicates with power cells through optical fibers. So medium voltage part and low voltage part are isolated, which makes system extremely safe and away from electromagnetic disturbance. In addition, when the auxiliary power supply is in failure, UPS will supply the auxiliary power to the controller for about 30 minutes, inverter can continue running.