Abstract：Under the normalsituation in many factories, the air compressor works in non-full loadconditions for a large part of time, as a result, the traditional control ofair compressor will waste the energy, result in inefficient. This article will introducea solution, which adopt INVT inverter to save energy, and supply a complete controlsystem. There is a energy saving result in this article.
Key Words:GD300-01, Air compressor, Energy saving
Now the new generation air compressorincludes a VFD system, which can save the energy under the non-full loadcondition, increase the efficiency. Adopting the VFD for air compressor, theadvantage is that the amount of air output can be changed by the air compressorhost speed to size adjustment. Compressor host motor by the speed controller tocontrol, it is different from the traditional machine is through the pressureloading and unloading to achieve.
Figure 1: pressure waveform under VFD and DOL situation.
We can find that the yellow space is theenergy saving part after adopt VFD system, with the traditional system, thepressure volatility is relatively large.
2. Advantageswith GD300-01 control system
Complete system withHMI and VFD
a.the system includes GD300-01 and HMI, no need another PLC or controller, whichcan reduce the system wiring, fault rate and cost
b.HMI software is standard, simple and easy to operate, includes the load/unloadbasic function, and the record of the system working status and alarm.
c.Adopt RS485 to communicate with HMI and VFD, control the pressure andtemperature automatically.
d.Includes the solution for valve and cooling fan, support PT100 temperaturesensor input. Setting the fan start/stop and working speed by master inverter.
e.Visual control function, set inverter parameters through the touch screen andsystem control parameters.
a.With vector control technique, air supply of air compressor can be combinedwith user's air consumption amount perfectly, which completely avoids unloadingpower loss.
b.Under discontinuity air consumption status, peak of current and torque areavoided through inverter start, so machine can perform unlimited startup andstop, truly accomplishing infinitely variable speeds of 0 ~ 100% and farthestlimiting idle work generation.
c.Special inverter for air compressor is convenient for installation. The low speed axial fan and modern vibrationisolation and noise reduction measures ensure compressor running with lownoise.
d.Thus it is convenient for user to place at production field. So long asequipment is in place, it can be fast connected and can be enabled immediatelyfor running.
Figure2: Air compressor control system structure
The GD300-01 isintegrated with the PLC/controller function which saves the cost forPLC/controller, and integrated with PT100 temperature detecting function whichrealizes the variable frequency control of the fan. Comparing with general asynchronousvariable frequency air compressor, the GD300-01 has advantages as follow:
Ø SupportIM and PM motor, be suitable for any kinds compressor.
Ø Withoutmotor bearing: the rotor with permanent magnet is directly installed on theextended axial of the male rotor. Without motor bearing for the structure whichomits the fault point of the motor bearing.
Ø Fastrespond speed on synchronous motor, great performance on exhaust response;
Ø Powersaving by controlling the speed of fan according to the exhaust temperature,better durability from the steady temperature of the system and entirecomponent. The noise is also reduced because of the fan is controlled byvariable frequency method.
4. Systemwiring diagram
Figure3: System wiring diagram
5. Compressorin customer site
Forthe 250kW air compressor, runs 24 hours every day for 1year, total time is 8560hours,load time is 2442 hours, unload time is 6318 hours, we calculate the price ofelectricity as 0.1 USD per kwh, the rated current is 450Amp.
a.No load loss: unload time * no load running current (1.732*0.38*175*0.85)*6318=618540kwh, considering the lower limit frequency is about 30Hz, the saving energy is 618540*40%=247416 kwh.
b.pressure loss: load time * pressure loss when increase 1bar = 0.6*7%*250kW*2442=25641kwh.
Thetotal saving energy = 247416+25641=273057kwh. 273057*0.1=27305.7USD.
TheGD300-01 air compressor solution is widely used in the air compressor market,only one inverter and HMI can replace the original compressor controller or PLC,this solution can save cost, simple wiring and easy commissioning saving time.INVT supply the full service and solution, widely welcomed by end-users.
 Operationmanual of GD300-01 of Shenzhen INVT Electric Co., Ltd Operation manual of GD10 of Shenzhen INVT Electric Co., Ltd