660V Medium Voltage Variable Frequency Drives for Conveyor
Conveyors are used in a broad range of industries and applications
to move packaged goods, assemblies, process byproducts, or any
material from one place to another. A process designer will
typically look for opportunities to use the force of gravity to
accomplish product movement. Electric motors are commonly used when
gravity cannot be employed or when the speed of a gravitational
fall needs to be controlled.Airports, mines, cement plants,
distribution facilities, assembly, and food processing plants all
utilize conveyors. Conveyors are typically constant torque loads,
meaning the required torque to drive a conveyor is independent of
speed. A fixed amount of torque is also required to overcome the
frictional, or machine drag, portion of the total load. Conveyors
can have nominal amounts of friction and machine inertia for which
to compensate.
Application Challenges
· Motor and Drive sizing
Conveyors requires a good deal of load and speed calculations,
combined with actual testing to ensure proper size (power)
requirements.
· Smooth product motion
Acceleration/Deceleration times combined with S-Curve “smoothing”
characteristics need fine-tuning to ensure the product is not
damaged and/or moved out of position for staging to subsequent
processes.
· Rapid deceleration or downhill speed control of conveyors cause
load regeneration in drives.
Care should be taken to ensure proper sizing of a drive’s dynamic
braking package or regenerative converter, to prevent drive
overvoltage faults.
· Electronic Gearing
Follow an external encoder to synchronize conveyor with other
sections of the process
· Coordinate conveyor motion with external machine axes
Reduce application development time
Features of G7 matching conveyor application
Features | Benefits |
Pulse Train I/O for speed control | Control speed of parallel or series conveyors by use of Pulse Train
I/O function in the drive. Eliminates the need for complex pulse to
analog converter. |
Momentary Powerloss Ride-thru
Automatic Fault Restart | The Momentary Powerloss Ride-thru and Fault Restart functions allow
the drive to continue operation without the need for attended
restart. |
Fully adjustable S-Curve and Accel/Decel rates | Smooth starting and stopping is achieved through the drives
Accel/Decel and S-Curve characteristics. |
Torque Limit | Torque Limit protects the load and other machinery from excessive
torque that may occur when the load fluctuates or seizes. |
Zero-Servo Function | The Zero Servo Function in the Closed Loop Flux Vector Mode makes a
mechanical brake unnecessary for tilt-tray and certain incline
conveyors that require a mechanical brake to stop. |
Torque Control in Closed loop Flux Vector Mode and Speed Droop
control in V/F Control Mode | Operating two or more conveyor motors in series. The load may shift
off between motors. The drive allows for load sharing by using
Torque Control or Droop Control. |
Power range of G7 VFD
Voltage: 660VAC (450VAC – 690VAC)
Power: 22kw/30HP – 400kw/535HP
Specification of G7 VFD
Item | Specification |
Input frequency | 50/60Hz |
Output frequency | 0-400Hz |
Overload current | 150% rated current 1min. |
Control mode | Close-loop vector control, sensor-less vector control, V/F control |
Starting torque | 150% 1hz (with PG 0hz) |
Control precision | ±0.2% (With PG ±0.02%) |
Torque precision | ±5% |
Setting frequency resolution | Digital command 0.01hz; analog command 0.03hz/60hz |
Output frequency resolution | 0.01Hz |
Frequency setting signal | -10V~+10V；0~+10V(20kΩ)；4~20mA |
Protection function | Over voltage, under voltage, over load, relay, overheat speed
stall, grounding, instant power cut compensation( within 2 sec for
operation mode. Continue to operate after the power is available),
Charging protection( not to display when the dc voltage of main
circuit is less than 50v) |
Enclosure | IP20 |
Cooling mode | forced air cooling |
Vibration | Less than 0.2g for 20hz |
Ambient temperature / Humidity | -10 Degrees~+40 Degrees / 20~90%Rh (no condensation) |
Tips:
A variable-frequency drive (VFD) is a system for controlling the
rotational speed of an alternating current (AC) electric motor by
controlling the frequency of the electrical power supplied to the
motor. A variable frequency drive is a specific type of
adjustable-speed drive. Variable-frequency drives are also known as
adjustable-frequency drives (AFD), variable-speed drives (VSD), AC
drives, microdrives or inverter drives. Since the voltage is varied
along with frequency, these are sometimes also called VVVF
(variable voltage variable frequency) drives.
