CHAPTER 3 INFLUENCE OF STATOR SLOT-SHAPE ON THE ENERGY CONSERVATION ASSOCIATED WITH THE SUBMERSIBLE INDUCTION MOTORS

Transcription

1 38 CHAPTER 3 INFLUENCE OF STATOR SLOT-SHAPE ON THE ENERGY CONSERVATION ASSOCIATED WITH THE SUBMERSIBLE INDUCTION MOTORS 3.1 INTRODUCTION The electric submersible-pump unit consists of a pump, powered by a medium-voltage three-phase induction motor. The power transmission system is integrated with riser-pipes. Pipe stacks are flanged together, and consist of riser-pipe with the power transmission system, concentrically mounted inside of each section. The power transmission system comprises a protective pipe with the copper conductors mounted inside. The motor is filled with water, and is being continuously circulated inside. The motor unit has forced-water lubrication. The water is fed down to thrust bearings and the mechanical seal through slots in the stator and returns to the surface through the rotor-gap/stator-gap and transmission system. 3.2 ANALYSIS APPROACH This chapter presents the performance improvement of submersible-pump sets ranging from 3-HP to 7-HP, by increasing the efficiency of squirrel-cage induction motor. For a three-phase induction motor, the stator winding consists of p poles and are distributed in space. The stator winding is usually connected to a three-phase balanced voltage source. The resulting currents in the stator produce a rotating magnetic field. The

2 39 rotor winding is often of squirrel-cage type with the number of poles equal to the number of poles in the stator. The currents are induced in the rotor conductive-bars. The interaction of the resultant magnetic field in the air-gap with the currents in the rotor conductive-bars produces an electromagnetic torque, which acts on the rotor in the direction of the rotation of the magnetic field in the air-gap. The performance of a three-phase induction motor is analyzed based on the equivalent circuit. Because of symmetry of the three phases, a single-phase equivalent circuit is shown in Figure 3.1, it can be used to analyze the characteristics of a three-phase induction motor. Figure 3.1 Equivalent Circuit of a 3 phase Induction Motor R 1 is the stator resistance, X 1 is the stator leakage-reactance, comprising of stator slot leakage-reactance, end-winding leakage-reactance, and differential leakage-reactance. X 2 and R 2 are the rotor leakage-reactance and the rotor resistance, respectively. X 2 includes rotor slot leakage-reactance, end-ring leakage-reactance, differential leakage-reactance, and skew-slot leakage-reactance. Due to the saturation phenomena in the magnetic leakage field, both X 1 and X 2 are non-linear parameters. All the parameters in the equivalent circuit are dependent on the stator and the rotor currents. In the exciting branch, X m denotes the magnetizing-reactance, and R c denotes the resistance corresponding to the iron-core losses. X m is a linearized non-linear parameter, whose value varies with the saturation degree in the main magnetic field. Given that V 1 is the external phase voltage applied to the phase terminals, the stator phase current I 1 and the rotor current I 2, which have been

3 4 referred to the stator, can be easily computed by analysing the equivalent circuit. The equivalent circuit parameters can be derived from the following geometrical and electrical parameters: 1) Geometrical Parameters: a) Stator and Rotor diameters (inner and outer) b) Axial core-length c) Number of slots in the Stator and the Rotor d) Geometrical shapes of the Stator and the Rotor slots 2) Electrical Parameters: a) Number of Poles b) Number of conductors in series per phase c) Winding pitch d) Cross-section of the conductor e) Short-circuited Cage ring section f) Skewing pitch of the Rotor slots These data are derived from the electromagnetic design of the machine. As shown in Figure 3.1, the actual rotor resistance R 2 and the rotor leakage-reactance X 2 have to be referred to the stator using Equation (3.1) and Equation (3.2), respectively. = (3.1) = (3.2)

4 41 The coefficient K for referring the rotor parameters to the stator side is shown in Equation (3.3). N ph is the number of stator conductors in series per phase, k w1 is the stator-winding coefficient (for the air-gap fundamental spatial harmonic), and N bars is the number of the squirrel-cage rotor bars. (3.3) It is important to note that any stator-phase-winding structure can always be described by N ph conductors in series per phase with an equivalent wire section (A wire ) suitable to carry the phase current. This means that only N ph and A wire are required for the equivalent circuit parameter computation, even if some parallel paths are used for the phase-winding realization (i.e., single-wire-parallel or bobbin-parallel) Stator and Rotor Resistances Equation (3.4). The stator winding resistance can be evaluated using Figure 3.2 and Figure 3.2 Length of the Average-turn of a Winding

5 42 =. (3.4) where is the resistivity of conductor material, L avg.turn is the length of the average-turn, and A wire is the cross-sectional area of the wire. Equation (3.4) is quite simple in itself, but some care has to be taken to define the averageturn length. As shown in Figure 3.2, this length is the addition of two components, namely, the part of turn embedded in the slot (L core ) and the end-winding length (L ew ). Equation (3.5) to Equation (3.7) gives the length of the average- turn of the conductor in the stator winding.. = 2( + ) (3.5) = (3.6) = 1 ( + ) (3.7) where D is is the inner diameter of the stator core, h s is the height of the stator slot, and k ew is the end-winding shape coefficient. The value of k ew is usually close to /2 for wire-windings, assuming a semi-circumference endwinding shape with a diameter equal to w. Typically, k ew is in the range of , depending on the actual end-winding length. n r is the pitch-shortening defined in number of slots, N pole is the number of poles (defined by the air-gap fundamental spatial harmonic), and N ss is number of the stator slots. Assuming the number of rotor phases to be equal to the number of bars, the phase-resistance of the cage is referred to single bar and to two adjacent ring sectors, as shown in Figure 3.3. The resistance contribution of a single bar can be computed by Equation (3.8), while the resistance contribution of one End-ring can be computed by Equation (3.9).

6 43 = (3.8) = (3.9) where K R is the skin-effect coefficient for the bar resistance, A bar is the cross-sectional area of the bar, L bar is the bar length, A a is the cross-sectional area of the cage-ring, and D a is average diameter of the cage-ring. Figure 3.3 Bar and Ring Currents in Rotor Cage By using, Equation (3.8) and Equation (3.9), it is possible to compute the equivalent rotor-phase resistance. As is well known, the calculation of this equivalent resistance is based on the total rotor-cage joulelosses. The phasor diagram for the current is shown in Figure 3.4, where, I b is the bar current and I a as the ring current. The relationship between the ring current and the end-bar current is given in Equation (3.1).

7 44 Figure 3.4 Phasor Diagram of Ring and End-bar Current (3.1) As a consequence, the total joule-loss dissipated in the rotor cage (P jr ) is defined by Equation (3.11). = + (3.11) Since each rotor bar can be considered as a phase of a multi-phase winding, the equivalent rotor-phase resistance is defined by Equation (3.12). = + (3.12) Classification of Magnetic Flux To calculate the inductive parameters, it is important to classify the magnetic fluxes through the machine. Figure 3.5 is used as a reference for this classification.

8 45 Figure 3.5 Flux-path in the Machine The flux in a rotating machine can be classified into two categories: A) With respect to the flux-path: The total flux linked ( total ) with a phase winding is the addition of two contributions, namely: 1) main, the main flux linked due to the magnetic field lines, crossing the air-gap. This flux is produced simultaneously by the stator and the rotor currents. 2) local, the local flux linked due to the following two components: a) The field lines close to the conductors in the slot and the two adjacent teeth ( sl ). b) The field lines around the end-windings ( hl ). B) With reference to the energy conservation: The total flux ( total ) linked with a phase winding is the addition of the following two components:

9 46 1) useful, the linked flux that is due to the fundamental distribution of air-gap flux density, and is a component of the main flux. 2) leakage, the linked flux that does not give appreciable contributions to energy conversion. With those of the above two classifications, it is possible to write the Equation (3.13) to Equation (3.15) for the total flux linked with the winding. = + (3.13) = + + (3.14) = + (3.15) As a consequence, the leakage-flux in the winding is calculated using Equation (3.16). = + + (3.16) The actual speed is mainly governed by the first harmonic flux; only the fundamental flux component is conventionally considered as useful in the electromechanical energy conversion. Flux components of higher orders are considered as leakage-components. As a consequence, with reference to Equation (3.15), the quantity ( ) is defined as the air-gap leakage-flux. This air-gap leakage flux is used for the calculation of the leakage-inductance.

10 Leakage-inductance The slot leakage-inductance (both for the stator and the rotor) can be calculated on the basis of the magnetic energy stored in the slot defined by Equation (3.17). E = L I (3.17) where is the slot-leakage-coefficient, L slot is the length of the winding part inside the slot, and I slot is the total current in the slot. Obviously, this current depends on the phase current (I Phase ), and on the type of phasewinding. Figure 3.6 Distribution of Magnetic-Field in the Slot L slot is used as general symbol: It is equal to L core for the stator winding and L bar for the rotor cage. Assuming, the permeability of iron to be infinite and that the magnetic field lines are parallel into the slot as shown in Figure 3.6, the magnetic energy stored in the slot is given by Equation (3.18). = ( ) ( ) (3.18) Given the x-coordinate, the magnetic field and the slot current are calculated by using Equation (3.19) and Equation (3.2).

11 48 ( ) = ( ) ( ) ( ) (3.19) = ( ) ( ) (3.2) As a consequence, the slot-leakage-coefficient is given by Equation (3.21). = ( ) ( ) (3.21) Since the permeability of iron is considered infinite, Equation (3.21) cannot be applied to closed rotor slots, because, the slot, the slot-leakage-coefficient should be infinite too. In this case, taking into account the inevitable heavy saturation of the slot closing magnetic wedge, an equivalent slot-opening has to be considered. Unfortunately, the selection of the width of the slot-opening is not a simple task and it can be done on the basis of the actual shape of the slot-closing zone. Generally, some trial-and-error steps based on the experience of the designer are required in order to obtain reasonable results. The phase slot leakage-inductance can be obtained by Equation (3.22). = (3.22) Alternatively, the leakage-inductance (L ) of a machine can be obtained as the sum of different leakage-inductances. According to the design-tradition of electrical motors, the leakage-inductance (L ) can be thought of as made up of the following partial leakage-inductances: Air-gap leakage-inductance (L g ) Slot leakage-inductance (L u ) Tooth-tip leakage-inductance (L d )

12 49 End-winding leakage-inductance (L w ) Skew leakage-inductance (L sq ) The leakage-inductance of the machine is the sum of these leakage inductances as shown in Equation (3.23). = (3.23) Air-gap inductance is given by Equation (3.24). L o 2 v 2 kwv m Tph DL g p v v,v 1 (3.24) where µ = Permeability of vacuum m g L D = Number of phases = Air-gap length = Effective core-length = Diameter of the core T ph = Number of turns per phase in a winding p = Number of pole-pairs = Ordinal of the harmonic k wv = Winding factor The term v, when equal to 1, in the Equation (3.24), represents the fundamental component, and thus the magnetizing-inductance (L m ) of the machine. The slot-inductance of a phase winding is obtained as follows:

13 5 Figure 3.7 shows the equivalent circuit of slot-inductance, and its value is determined by Equation (3.25). Figure 3.7 Equivalent Circuit of Slot-Inductance L u = 4m Q o 2 u (3.25) where Q = Number of slots u = Permeance factor of the slot Figure 3.8 Slot Model Equation (3.26) is used to determine the permeance factor of the slot ( u ), using the dimensions of the slot model as shown in Figure 3.8.

14 51 u = h 4 3b 4 + h 3 b 4 + h 1 b 1 + h 2 b 4 -b 1 ln b 4 b 1 (3.26) Tooth-tip leakage-inductance is determined using Equation (3.27). = (3.27) d = Permeance factor of tooth-tip End-winding leakage-inductance (L w ) calculation is given by Equation (3.28) = (3.28) l w = Average length of the end-winding w = Permeance factor of end-winding q = Number of slots per pole per phase Equation (3.29) shows the Skew leakage-inductance (L sq ) = (3.29) where =, the Leakage factor caused by skewing k sq = skewing factor =

15 CALCULATION OF PERFORMANCE PARAMETERS The magnetic energy stored in a slot can be calculated by using any one of the Flux analysis softwares, namely, 2-D, RMxprt, and MotorPro, after completion of the initial design using low-loss materials. The magnetic circuit of the motor is constituted by the lamination of the stator, the rotor, and the air-gap. The energy conversion is assisted by the flux in the air-gap, driven by magneto-motive-force (mmf) produced in the stator winding. The mmf required to drive the flux is influenced by the reluctance of the magnetic circuit. The reluctance of the magnetic circuit is determined by the length and the relative permeability of the material as given in Equation (3.3). = (3.3) where S = Reluctance = Length of the magnetic circuit = Permeability of free space = Relative permeability A = Area of the magnetic circuit The mean length of the magnetic circuit is influenced by the shape of the slot and the air-gap. Material composition of stamping influences the relative permeability and the saturation factor coefficient. Reduced reluctance circuit needs less mmf to force the flux, and hence results in less magnetizing current. Hence, the output power, power factor, and efficiency improve significantly. This could be understood from the equivalent circuit shown in Figure 3.1, and Equation (3.31) to Equation (3.37). The electromagnetic power (P m ), otherwise called as the air-gap power, is determined by Equation (3.31). = 3 (3.31)

16 53 The electromagnetic torque (T m ) is calculated using Equation (3.32). = (3.32) where, denotes the synchronous speed in rad/s. Equation (3.33) gives the mechanical shaft output torque (T sh ). = (3.33) where, T fw denotes the frictional and windage torque. The output power (P o ) is shown in Equation (3.34). = (3.34) where r = (1 s) denotes the rotor speed in rad/s. Equation (3.35) is used to calculate the input power to the motor (P i ). = (3.35) where P fw, P rc, P cl, P sc, and P l denote the frictional and windage losses, the rotor copper loss, the iron-core loss, the stator copper loss, and the stray loss, respectively. The power factor is determined by Equation (3.36). = (3.36) Equation (3.37) is used to determine the efficiency. = 1 (3.37)

17 ANALYSIS USING ROTATIONAL MACHINE EXPERT Rotational Machine Expert (RMxprt) is an interactive software package from ANSOFT Corporation used for the design and analysis of electrical machines. When a new project is started in RMxprt, the type of motor is to be selected. The parameters associated with the selected machine are given as input in the property window. The property windows are accessed by clicking each of the machine elements; for example, stator, rotor, and shaft under machine in the project tree. Solution and output options such as the rated output, torque, and load current, etc., are set by adding a solutionsetup in analysis of the project tree. A 3-phase, 38 V, 2-pole submersible induction motor with the power range 3-HP to 7.5-HP has been chosen, based on the market requirement. (Source: TEXMO Industries, CRI Pumps, DECCAN Industries, and PSG Industrial Institute). Different stator, rotor slotshapes have been considered for optimisation. The stator and rotor slotmodels used for simulation are shown in Figure 3.9 and Figure 3.1, respectively. Figure 3.9 Stator Slot-models used for Optimisation

18 55 Figure 3.1 Rotor Slot-models used for Optimisation The various dimensions of slots pertaining to Stator and Rotor are shown in Table 3.1 and Table 3.2, respectively. Table 3.1 Dimensions of Stator Slots Dimension (mm) Slot Type B S B S1 B S2 H S H S1 H S2 R S1 R S2 A B C D E F Table 3.2 Dimensions of Rotor Slots Dimension (mm) Slot Type B S B S1 B S2 H S H S1 H S2 R S

19 56 All the design values related to each section as mentioned in Figure 3.11 have been configured in the software, namely, machine type, main dimensions, material characteristics, BH and BP-curves for the stamping, type of shaft material (SS-37), and body material (cast iron, aluminium, and SS-34). The basic process in RMxprt is illustrated with the help of the flowchart in Figure Start Define Data for 3-phase Induction Motor General Data Stator Data Rotor Data Solution Data Machine type No. of Poles Stray loss Friction loss Windage loss Reference speed Outer diameter Inner diameter Length Type of Steel Stacking factor No. of slots Slot-Model Slot dimensions Winding details Outer diameter Inner diameter Length Type of Steel Stacking factor No. of slots Slot-Model Slot dimensions Winding details Skew width Rotor type Duty-cycle Type of Load Rated output Rated voltage Rated speed Operating temperature Winding connection Frequency Analysis of Machine Add a solution setup Validation check Analyse Design Output of Machine Design sheet Performance table Performance curves Figure 3.11 Flowchart for Basic Process in RMxprt The iterations have been performed, using the optimetrics tool shown in Figure 3.12, by choosing different combinations of core-length, number of turns per phase, and magnetic loading for 3-phase, 5-HP, 38 V submersible induction motor.

20 57 Start RMxprt Model (initial design) Define design variables and its range of values Add parametric setting Define performance attributes needed for calculation Analyse Apply optimum result for initial design RMxprt Model (optimised design) Figure 3.12 Flowchart for Optimetrics Tool in RMxprt Table 3.3 to Table 3.8 show the results obtained from the simulation for different slot-model combinations. The parameters that influence the magnetic circuit, namely, Stator Leakage-reactance, Magnetizing-reactance, Rotor Leakage-reactance, Resistance corresponding to Iron-core Loss, Stator Phase Current, and Magnetizing Current have been considered for the selection of optimum slot-model.

21 58 Table 3.3 Parameters for Slot-A Combination Parameters Slot-1 Slot-2 Slot-3 Slot-4 Stator Leakage-reactance ( ) Magnetizing-reactance ( ) Rotor Leakage-reactance ( ) Resistance Corresponding to Iron-core Loss ( ) Stator Phase Current (A) Magnetizing Current (A) Table 3.4 Parameters for Slot-B Combination Parameters Slot-1 Slot-2 Slot-3 Slot-4 Stator Leakage-reactance ( ) Magnetizing-reactance ( ) Rotor Leakage-reactance ( ) Resistance Corresponding to Ironcore Loss ( ) Stator Phase Current (A) Magnetizing Current (A) Table 3.5 Parameters for Slot-C Combination Parameters Slot-1 Slot-2 Slot-3 Slot-4 Stator Leakage-reactance ( ) Magnetizing-reactance ( ) Rotor Leakage-reactance ( ) Resistance Corresponding to Ironcore Loss ( ) Stator Phase Current (A) Magnetizing Current (A)

22 59 Table 3.6 Parameters for Slot-D Combination Parameters Slot-1 Slot-2 Slot-3 Slot-4 Stator Leakage-reactance ( ) Magnetizing-reactance ( ) Rotor Leakage-reactance ( ) Resistance Corresponding to Iron-core Loss ( ) Stator Phase Current (A) Magnetizing Current (A) Table 3.7 Parameters for Slot-E Combination Parameters Slot-1 Slot-2 Slot-3 Slot-4 Stator Leakage-reactance ( ) Magnetizing-reactance ( ) Rotor Leakage-reactance ( ) Resistance Corresponding to Iron-core Loss ( ) Stator Phase Current (A) Magnetizing Current (A) Table 3.8 Parameters for Slot-F Combination Parameters Slot-1 Slot-2 Slot-3 Slot-4 Stator Leakage-reactance ( ) Magnetizing-reactance ( ) Rotor Leakage-reactance ( ) Resistance Corresponding to Iron-core Loss ( ) Stator Phase Current (A) Magnetizing Current (A)

23 6 It could be concluded from the parameters in Table 3.3 to Table 3.8 that the combination of Slot-A type stator slot with Slot-2 type rotor slot contribute to a good magnetic circuit. The advantages of this combination are: Reduced Stator and Rotor Leakage-reactances Increased Magnetizing-reactance Increased Resistance corresponding to Iron-Core Loss Reduced Stator Phase Current Reduced Magnetizing Current The output power of the underwater motor can be increased by reducing the magnetizing current. Reduced magnetizing current will improve the operating power factor. A cumulative operation of more number of such motors will lead to energy-saving and the load factor of the connected distribution transformer will come down, resulting in good voltage regulation and high Transformer utilization factor. Existing Slot-D type stator slot and Slot-1 type rotor slot combination shown in Figure 3.13a are compared with the proposed Slot-A type stator slot and Slot-2 type rotor slot shown in Figure 3.13b. Submersible motors with the ratings of 3-HP, 5-HP, 6-HP, and 7.5-HP have been considered for optimisation.

24 61 (a) (b) Figure 3.13 Stamping Models (a) Slot-D Type Stator and Slot-1 Type Rotor (b) Slot-A Type Stator and Slot-2 Type Rotor For analysis in RMxprt, a 3-phase, 38 V, 2-pole, 5 Hz, and starconnected submersible induction motor type has been considered with the specifications given in Table 3.9. Table 3.9 Specifications of the Motors S. No. Parameter 3-HP 5-HP 6-HP 7.5-HP 1 Outer diameter of the Stator (mm) Inner Diameter of the Stator (mm) Length of the Stator core (mm) Air-gap (mm) Inner diameter of the Rotor (mm) End-Ring Width (mm) End-Ring Length (mm) End-Ring Height (mm) Number of Stator Slots Number of Rotor Slots Conductors per slot

25 62 The stator and rotor stampings are common for the selected range of motors. M43_29G-grade-stamping has been used for both the stator and the rotor. The core-length has been varied based on the power rating of the motor, the magnetic loading, and the electric loading values are adjusted to optimize the core-length and other performance parameters. The electric loading value is kept slightly higher for the submersible motor compared to the normal industry-type motor because of the forced-water cooling. The number of conductors per slot and End-Ring width have also been changed so as to meet the design requirements. 3.5 SIMULATION RESULTS With fixed operating conditions, the machines have been simulated in RMxprt and the results are tabulated as shown in Table 3.1 and Table Following inferences could be made from Table 3.1 and Table 3.11: The leakage-reactance of stator and rotor, namely, Slot, Endwinding, Differential, and Skewing Leakage-reactance values have got reduced. Increased values of Iron-core Loss Resistance and Magnetizing-reactance reduce the loss-component current and the magnetizing current, resulting in improvement of the operating power factor. The stator phase current of the proposed slot type motor is less, when compared to that of the existing slot type motor. There is a significant improvement in the efficiency of the motor with the proposed slot-shape.

26 63

27 64

28 65 (a) (b) Figure 3.14 Flux Distribution (a) Existing Slot (b) Proposed Slot Flux distribution in the Motor is shown in Figure The flux density with the proposed stator slot is found to be from 1.22 Tesla to 1.55 Tesla; but in the existing stator, it is from 1.2 Tesla to 1.7 Tesla. Since the magnetic flux density is less in the proposed slot, there is a reduction in the required magnetizing current. 3.6 REAL-TIME IMPLEMENTATION AND RESULTS The stampings and the test setup are shown in Figure 3.15 and Figure 3.16, respectively.

29 66 (a) (b) Figure 3.15 Stampings (a) Existing (b) Proposed (a) (b) Figure 3.16 Test Set-up (a) Testing Panel (b) Pump Loading The performance test reports for 3-HP, 5-HP, 6-HP, and 7.5-HP pump-sets, with the existing and the proposed motor slot-shape are shown in Table 3.12 to Table 3.19.

30 67 Table 3.12 Performance Test of 3-HP Submersible-pump-set with the Existing slot-shape S.No. Speed (rpm) Delivery gauge reading (Kgf/cm 2 ) Total head (m) Rise in Tank (cm) Time for rise (s) Input Discharge Current Power (lpm) (A) (kw) Pump output (kw) Overall efficiency (%) Table 3.13 Performance Test of 3-HP Submersible-pump-set with the Proposed slot-shape S.No. Speed Delivery gauge reading (rpm) (Kgf/cm 2 ) Total head (m) Rise in Tank (cm) Time for rise (s) Discharge (lpm) Current (A) Input Power (kw) Pump output (kw) Overall efficiency (%)

31 Head (m) Overall Efficiency (%) Current (A) Motor Input (kw) Discharge (lps) (a) Head (m) Overall Efficiency (%) Current (A) Motor Input (kw) Discharge (lps) (b) Figure 3.17 Pump Performance Curve: 3-HP (a) Existing (b) Proposed

32 Current in the Proposed Design (A) Discharge in the Existing Design (lpm). Current in the Existing Design (A) Discharge in the Proposed Design (lpm) Delivery Gauge Reading (kgf/cm 2 ) (a) Current in the Existing Design (A) pf in the Existing Design. Current in the Proposed Design (A) pf in the Proposed Design Delivery Gauge Reading (kgf/cm 2 ) (b) Figure 3.18 Performance Comparison Curve: 3-HP (a) Discharge and Current (b) Current & Power factor

33 7 Table 3.14 Performance Test of 5-HP Submersible-pump-set with the Existing slot-shape S.No. Speed (rpm) Delivery gauge reading (Kgf/cm 2 ) Total head (m) Rise in Tank (cm) Time for rise (s) Discharge (lpm) Current (A) Input Power (kw) Pump output (kw) Overall efficiency (%) Table 3.15 Performance Test of 5-HP Submersible-pump-set with the Proposed slot-shape S.No. Speed (rpm) Delivery gauge reading (Kgf/cm 2 ) Total head (m) Rise in Tank (cm) Time for rise (s) Discharge (lpm) Current (A) Input Power (kw) Pump output (kw) Overall efficiency (%)

34 Head (m) Overall Efficiency (%) Current (A) Motor Input (kw) Discharge (lps) (a) Head (m) Overall Efficiency (%) Current (A) Motor Input (kw) Discharge (lps) (b) Figure 3.19 Pump Performance Curve: 5-HP (a) Existing (b) Proposed

35 Current in the Proposed Design (A) Discharge in the Existing Design (lpm). Current in the Existing Design (A) Discharge in the Proposed Design (lpm) Delivery Gauge Reading (kgf/cm 2 ) (a) 15 1 Current in the Existing Design (A) pf in the Existing Design. Current in the Proposed Design (A) pf in the Proposed Design Delivery Gauge Reading (kgf/cm 2 ) (b) Figure 3.2 Performance Comparison Curve: 5-HP (a) Discharge and Current (b) Current and Power factor

36 73 Table 3.16 Performance Test of 6-HP Submersible-pump-set with the Existing slot-shape S.No. Speed (rpm) Delivery gauge reading (Kgf/cm 2 ) Total head (m) Rise in Tank (cm) Time for rise (s) Discharge (lpm) Current (A) Input Power (kw) Pump output (kw) Overall efficiency (%) Table 3.17 Performance Test of 6-HP Submersible-pump-set with the Proposed slot-shape S.No. Speed (rpm) Delivery gauge reading (Kgf/cm 2 ) Total head (m) Rise in Tank (cm) Time for rise (s) Discharge (lpm) Current (A) Input Power (kw) Pump output (kw) Overall efficiency (%)

37 Head (m) Oveall Efficiency (%) Current (A) Motor Input (kw) Discharge (lps) (a) Head (m) Oveall Efficiency (%) Current (A) Motor Input (kw) Discharge (lps) (b) Figure 3.21 Pump Performance Curve: 6-HP (a) Existing (b) Proposed

38 75 Current in the Existing Design (A) Discharge in the Existing Design (lpm) Current in the Proposed Design (A) Discharge in the Proposed Design (lpm) Delivery Gauge Reading (kgf/cm 2 ) (a) 1 Current in the Existing Design (A) pf in the Existing Design Current in the Proposed Design (A) pf in the Proposed Design Delivery Gauge Reading (kgf/cm 2 ) (b). Figure 3.22 Performance Comparison Curve: 6-HP (a) Discharge and Current (b) Current and Power factor

39 76 Table 3.18 Performance Test of 7.5-HP Submersible-pump-set with the Existing slot-shape S.No. Speed (rpm) Delivery gauge reading (Kgf/cm 2 ) Total head (m) Rise in Tank (cm) Time for rise (s) Discharge (lpm) Current (A) Input Power (kw) Pump output (kw) Overall efficiency (%) Table 3.19 Performance Test of 7.5-HP Submersible-pump-set with the Proposed slot-shape S.No. Speed (rpm) Delivery gauge reading (Kgf/cm 2 ) Total head (m) Rise in Tank (cm) Time for rise (s) Discharge (lpm) Current (A) Input Power (kw) Pump output (kw) Overall efficiency (%)

40 77 Head (m) Overall Efficiency (%) Current (A) Motor Input (kw) Discharge (lps) (a) Head (m) Overall Efficiency (%) Current (A) Motor Input (kw) Discharge (lps) (b) Figure 3.23 Pump Performance Curve: 7.5-HP (a) Existing (b) Proposed

41 78 Current in the Proposed Design (A) Discharge in the Existing Design (lpm) (a) Current in the Existing Design (A) Discharge in the Proposed Design (lpm) Delivery Gauge Reading (kgf/cm 2 ) Current in the Existing Design (A) pf in the Existing Design Current in the Proposed Design (A) pf in the Proposed Design Delivery Gauge Reading (kgf/cm 2 ) (b) Figure 3.24 Performance Comparison Curve: 7.5-HP (a) Discharge and Current (b) Current and Power factor

42 79 Performance Comparison Curves for 3-HP, 5-HP, 6-HP, and 7.5-HP, Pump-sets have been depicted in Figure 3.17 to Figure From the performance curves, the following inferences have been made: The current drawn from the supply gets reduced by 1 to 1.7 A, and the power factor has also got significantly improved. Input power consumed by the pump-set gets significantly reduced by 13 to 3 W. There is an increase in speed of the pump-set by 15 to 3 rpm, and this results in increase in the discharge of water by 3 to 7 lpm. The overall efficiency of the pump-set has gone up by 3 to 7 %. Therefore, the adoption of these motors in the agriculture field can give immense benefits to the user, as well as to the country and the global environment at large.