Beijing Leader & Harvest Electric Technologies Co., Ltd.

Beijing Leader & Harvest Electric Technologies Co., Ltd.

Address: South Zone of Industrial Park, Yangfang, Changping District, Beijing, P.R.China
Tel: +86-10-69764859
Fax: +86-10-69765220

Variable Frequency Drive

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A variable frequency drive, which is also called VFD, is used for controlling the frequency of the electrical power supplied to AC electric motor, thus controlling the rotational speed of the motor. Variable frequency drives are also known as adjustable frequency drives (AFD), variable-speed drives (VSD), AC drives, microdrives or inverter drives. These drives are sometimes also called variable voltage variable frequency (VVVF) drives, for the voltage is varied along with frequency. A variable frequency drive system generally consists of an AC motor, a controller and an operator interface.

    1. A Variable Frequency Drive HARSVERT-A series VFD is a masterpiece of outstanding performance and high reliability, which is widely used for the energy-saving application of the normal motors of fans, pumps, compressors, mills, conveyors and lifts. HARSVERT-A series VFD uses new type of IGBT with advanced microcomputer control ...
    1. VA Variable Frequency Drive Input current harmonic: <3% (comply with standard IEEE519);
      Input power factor: >0.95(>20% load);
      Output current harmonic: <2.5%; output DC component: <1% ...
    1. S Variable Frequency Drive HARSVERT-S series VFD supplies perfect speed-adjustment for the synchronous motor and accurate excitation current control for the exciter. It improves the reliability and reduces the cost of the retrofit by using VFD on synchronous motor ...
    1. VS Variable Frequency Drive Vector control for the speed-adjustment of synchronous motor;
      Start ability for starting the synchronous motor with load;
      The response time of dynamic torque: less than 150ms ...
    1. FVS Variable Frequency Drive PWM rectifier technology. Energy can flow bi-directionally between power grid and the motor;
      Vector control for synchronous motor;
      Strong start up with load in low speed, start torque can reach to 150% rated torque ...
    1. FVA Variable Frequency Drive Speed sensor-less vector control: speed-adjusting range: 100:1; static speed precision: 0.5%; start torque: 150% rated torque; the response time of dynamic torque: less than 200ms;
      Speed close loop vector control: speed-adjusting range: 500:1; static speed precision: 0.1% ...

Definition of HARSVERT Variable Frequency Drive model
Model is explained as follows:

HARSVERT Variable Frequency Drive (VFD)

1 Rated output current is □□□A, including 3 digital bits.
2 Rated output voltage: 03-3kV; 03.3-3.3kV; 04.16-4.16kV; 06-6kV; 06.6-6.6kV; 10-10kV; 11-11kV.
3 Control mode: A- asynchronous motor; S-synchronous motor; VA-asynchronous motor vector control; VS- synchronous motor vector control; FVA-asynchronous motor, regenerative drive; FVS-synchronous motor, regenerative drive;

For example:

HARSVERT Variable Frequency Drive (VFD)

HARSVERT Variable Frequency Drive parameters

Item Parameter
Standard IEC61800-4:2002 Q/CP BLH003-2007
Phase, frequency Three phase, 50/60Hz
Allowable range of frequency fluctuation ±10%
Allowable range of voltage fluctuation ±10%
Input power factor >0.95 (at more than 20% load)
Output voltage range 3kV~11kV
Output current range 25A~600A
VFD capacity 280kW~8000kW
Over-load capacity 120% of rated current for 60 seconds per 10minutes; 150% of rated current for 3s; 200% immediately
Output frequency 0.5-120Hz
Basic performance
Efficiency ≥96% (including phase-shifting transformer)
Harmonics Comply with IEEE 519 standard
Frequency resolution 0.01Hz
Touch screen HMI Output frequency, voltage, current, power; input voltage, current, power, power factor; failure/alarm; log; parameter setup; waveform display, etc.
Control mode V/F control; Vector control
Acceleration/deceleration time 0~3200s, Adjustable
Digital I/O 5/5channels digital inputs/outputs; extendable
Communication port and protocols RS485; Modbus-RTU[OPTIONAL Protocols: Profibus-DP, TCP/IP, DeviceNet, GPRS wireless transmission]
Control signal between Power cell and Controller Connected by optical fibre
Auxiliary power supply Single phase AC110V/ AC220V/ AC230V; or DC220V Capacity: 3kVA
PID function Embedded PID regulator
Control function Auto re-start after the recovery of main medium voltage; Torque booster; Frequency-skip; Self-diagnosis; Fly-start; Synchronous transfer[OPTIONAL]; Cell bypass[OPTIONAL]
Operation mode Local/Remote; Open loop/Close loop
Frequency given Manually setting in the interface/Analog signal
Status output of VFD analog output and digital output
Work field Inside without corrosive and explosive gas and without dust, Altitude of below 1000m.
Temperature/humidity Temperature: 0~+45oC; Humidity: below 90%, no condensation
Storage condition -25~+55℃
Protection Over current, Short circuit, Earth fault, Over voltage, Low voltage, Over load, Over heat, Phase loss.
Enclose IP20~IP41
Cooling Air cooling/Hot air to Chiller water heater exchanger cooling

Application field
HARSVERT- series of medium voltage VFD can usually be applied in these fields:
Power generation: induced draft fans, forced draft fans, condensate exhausting pump, boiler feed water pumps, primary fan, secondary fan, circulating pump, mill fan, slurry pump, mill ...

System principle
System configuration
Multi-level voltage source VFD 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. VFD is composed of phase-shifting transformer, power cells and controller ...

Main Features
Normal start
At normal start status, VFD 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, VFD will start and accelerate to the frequency of power grid regardless of the given frequency. When the output frequency of VFD reaches the frequency of power grid (set in main interface) ...

Technical Data
1 Rated output current is □□□A, including 3 digital bits.
2 Rated output voltage: 03-3kV; 03.3-3.3kV; 04.16-4.16kV; 06-6kV; 06.6-6.6kV; 10-10kV; 11-11kV.
3 Control mode: A- asynchronous motor; S-synchronous motor; VA-asynchronous motor vector control ...

Technical Certification