Abstract：Under the normal situation in many factories, the air compressor works in non-full load conditions for a large part of time, as a result, the traditional control of air compressor will waste the energy, result in inefficient. This article will introduce a solution, which adopt INVT inverter to save energy, and supply a complete control system. There is a energy saving result in this article.
Key Words: GD300-01, Air compressor, Energy saving
Now the new generation air compressor includes a VFD system, which can save the energy under the non-full load condition, increase the efficiency. Adopting the VFD for air compressor, the advantage is that the amount of air output can be changed by the air compressor host speed to size adjustment. Compressor host motor by the speed controller to control, it is different from the traditional machine is through the pressure loading and unloading to achieve.
Figure 1: pressure wave form under VFD and DOL situation.
We can find that the yellow space is the energy saving part after adopt VFD system, with the traditional system, the pressure volatility is relatively large.
2. Advantages with GD300-01 control system
Complete system with HMI and VFD
a.the system includes GD300-01 and HMI, no need another PLC or controller, which can reduce the system wiring, fault rate and cost.
b.HMI software is standard, simple and easy to operate, includes the load/unload basic function, and the record of the system working status and alarm.
c.Adopt RS485 to communicate with HMI and VFD, control the pressure and temperature automatically.
d.Includes the solution for valve and cooling fan, support PT100 temperature sensor input. Setting the fan start/stop and working speed by master inverter.
e.Visual control function, set inverter parameters through the touch screen and system control parameters.
High efficiency energy-saving
a.With vector control technique, air supply of air compressor can be combined with user's air consumption amount perfectly, which completely avoids unloading power loss.
b.Under discontinuity air consumption status, peak of current and torque are avoided through inverter start, so machine can perform unlimited start up and stop, truly accomplishing infinitely variable speeds of 0 ~ 100% and farthest limiting idle work generation.
c.Special inverter for air compressor is convenient for installation. The low speed axial fan and modern vibration isolation and noise reduction measures ensure compressor running with lownoise.
d.Thus it is convenient for user to place at production field. So long as equipment is in place, it can be fast connected and can be enabled immediately for running.
Figure2: Air compressor control system structure
The GD300-01 is integrated with the PLC/controller function which saves the cost for PLC/controller, and integrated with PT100 temperature detecting function which realizes the variable frequency control of the fan. Comparing with general asynchronous variable frequency air compressor, the GD300-01 has advantages as follow:
Ø Support IM and PM motor, be suitable for any kinds compressor.
Ø Without motor bearing: the rotor with permanent magnet is directly installed on the extended axial of the male rotor. Without motor bearing for the structure which omits the fault point of the motor bearing.
Ø Fast respond speed on synchronous motor, great performance on exhaust response;
Ø Power saving by controlling the speed of fan according to the exhaust temperature,better durability from the steady temperature of the system and entire component. The noise is also reduced because of the fan is controlled by variable frequency method.
4. System wiring diagram
Figure3: System wiring diagram
5. Compressoring customer site
For the 250kW air compressor, runs 24 hours every day for 1year, total time is 8560 hours,load time is 2442 hours, unload time is 6318 hours, we calculate the price of electricity 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.
The total saving energy = 247416+25641=273057kwh. 273057*0.1=27305.7USD.
The GD300-01 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