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Q.How to choose voltage rating for fans?

A.It depends on the power distribution system you are using.Here's the various voltage used in North America.

SINGLE PHASE 120 Single Phase 120 often called house current is the AC power used in commercial buildings and houses to power lights and small appliances. The output voltage is 120Vac line to neutral (L-N). Line to neutral may also be called phase to neutral. There is both a 2 wire and a 3 wire configuration. The 2 wire configuration consists of Phase A and Neutral. This configuration is older and is being replaced by the 3 wire configuration which adds the earth ground connection. The grounded neutral conductor and ground provides a significant safety improvement. See Figure 1. Depending on the actual local power distribution standards, the single phase the voltage may be listed as 110Vac, 115Vac, 117vac or 120 Vac. Even with these stated nominal vales, variation do occur due to grid power demands, transformer losses, and voltage drops due to wiring impedances.

                                                                             

Single Phase 120/240 Single phase 120/240 is commonly seen as the source for AC power to household cloths driers. It may also be called Split Phase 240. This configuration consists of 2 voltage legs that are 180 degrees apart. The voltage between the two legs (called phase to phase or line to line) is 240V and the phase to neutral voltage is 120V.The 120/240 notation identifies the phase to neutral voltage followed by the phase to phase voltage. Some list the phase to phase voltage first so it may also be called 240/120 single phase. See Figure 2. Medium power supplies ( < 5 kW) will operate on this voltage configuration.                                                                         

                                                                         
3 Phase Configurations AC power is usually distributed in a facility in a 3-phase system consisting of 5 wires. Three of the wires are current carriers and are called phases. These 3 phases are 120 degrees out of phase from each other. The fourth wire is the neutral wire. The neutral wire will not have current flowing in it as long as the current in the three phases are matched. The 5th wire is Earth Ground. This system is commonly called a 3 phase wye because of the Y shape of the phases.
A 3 phase Wye configuration is shown in Figure 3.
                                                                                 
In the USA the most common configuration is 208Y/120. This indicates that line to line (L-L) voltage is 208Vac in a WYE configuration and the line to neutral (L-N) voltage is 120Vac. It is also sometimes designated 120/208Vac, 120/208WYE, 208/120 WYE, 4 wire WYE or 120/208Y. See Figure 4. Most power supplies > 5 kW will operate on this configuration.
 
                                                                              
 
For higher power capabilities another configuration in the USA is 480Y/277. In this case the line to line voltage is 480Vac in a WYE configuration and the line to neutral voltage is 277Vac. See Figure 5. This configuration is often an optional voltage for most power supplies 5 kW and larger.
 
 
                                                                               
 

Since each phase in a 3 phase wye configuration is 120 degrees from each other, the L-L voltage is not the algebraic sum of the L-N voltages but a vector addition. A quick method that can be used if the phase angles are 120 degrees apart is to use the L-N voltage multiplied by √3.

V L-N √3 = V L-L (i.e. 120Vac 1.7333 = 208 Vac)

V L-L ÷ 1.7333 = V L-N (i.e. 480Vac ÷ 1.7333 = 277 Vac)

Another variation of the 4 wire WYE configuration is the 5 wire wye configuration that adds an Earth Ground wire which is usually connected to neutral at the circuit breaker panel. See Figure 6.

                                                                                 

3 Phase Delta Configuration Although the WYE configuration is the most common configuration there also is the Delta configuration. See Figure 7. In this configuration, there is no neutral. So the voltage is always a line to line measurement. Vline = Vphase (i.e. 208Vac = 208Vac) Iline = 3 Iphase (If the phase current is 50 Amps the line current is 1.733 * 50 Amps = 86.6 Amps) One advantage of a Delta configuration is that it does not have a neutral and therefore if a phase winding should fail the phase voltage at the load will remain constant.

                                                             

                                                                                   

Open Wye Configuration There are other distributions that are not common but may be encountered. The first is the 3 phase “open wye”.See Figure 8. This configuration can be used to allow power to be maintained if a phase fails or is in need of maintenance. This would require using a standard 3 phase wye configuration made from 3 single phase transformers. If one of the phases needs to be taken off line for repair the remaining two transformers can be set up in an open wye configuration and continue to operate. When the third phase transformer is available again the three transformers can be reconfigured in a standard wye configuration.The open phase voltage equals the line voltage/2 and the phase current equals the line current. Power is half that of a 3 phase wye configuration.

V phase = V line / 2

I phase = I line

                                                                               

3 Phase Open Delta Configuration The 3 phase Open Delta configuration would serve the same purpose as the open Wye configuration discussed above and like the open wye would also require using single phase transformers. In this configuration the phase voltage equals the line voltage and the load current equals the phase A and the phase B current. The power available from this configuration is 2/3 of a 3 phase Delta configuration. This configuration is sometimes called V configurations. V phase = V line I phase A = I phase B = I load B I L-N = 1.73 * I Phase A

                                                                                   

240V Split Phase Delta The 240V Split Phase Delta or High Leg Delta is a modified 240Volt 4 wire Delta with one phase center taped to provide two phases with 120Vac and a High leg which provides 208Vac in addition to 240 Vac. With this configuration a single system can provide different voltages for a facility that supports offices and factory machinery. This configuration is also known as dog leg or stinger leg. See Figure 10.

 

                                                                                    

 

 

 

Q.How to choose frequency rating for fans?

A.It depends on the power distribution system you are using.Consult your electrical contractor.

                                                           

                                                                                   world map of voltage and frequency 

For now,all of our fans use induction motors.The velocity at which an electric induction motor operates depends on input power frequency and the number of electrical magnetic poles.

                                                          

                                                                                               motor speed VS frequency  

 

 

Q.What is IE1, IE2 and IE3 motors?

A.IEC 60034 is an international standard of the International Electrotechnical Commission for rotating electrical machinery.IEC 60034-30 specifies energy-efficiency classes for single-speed, three-phase, cage-induction motors with 2, 4 or 6 poles. It classifies three classes: IE1 (standard), IE2 (high) and IE3 (premium). For each class the efficiency is defined for a rated output range from 0.75 to 375 kW. In the European Community the IE2 class is mandatory for all new motors since 16 June 2011. The IE3 class will be mandatory from 1 January 2015 (7.5–375 kW) and 1 January 2017 (0.75–375 kW).

                                                               

 

Q.What is the difference between IE efficiency rating and EFF efficiency rating?

A.In 1998, the European Committee of Manufacturers of Electrical Machines and Power Electronics (CEMEP) developed three classes (i.e. EFF1, EFF2 and EFF3) to describe the energy efficiency of motors. It is a voluntary agreement between the electrical motor manufacturers and the European Commission. However, the agreement expired on 16th June,2011. The EFF has 3 classes, i.e. EFF1, EFF2 and EFF3 respectively. EFF1 is the most energy efficient, while EFF3 is the least energy efficient.

    In order to harmonize the standards describing motor energy efficiency, theInternational Electrotechnical Commission (IEC) has developed the International Efficiency (IE) classes through collaboration with the National Electrical Manufactures Association (NEMA), CEMEP, the Japan Electrical Manufacturers’ Association (JEMA),the Institute of Electrical and Electronics Engineers (IEEE) and other international organizations. The IE Classification is defined by IEC 60034-30-1. The latest version of IEC 60034-30-1 was published in June 2014.                                                       

                                                             

 

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