The Pitch of coil spring formula is defined as the axial distance between adjacent coils in uncompressed state of spring and is represented as p = L f /(N t-1) or Pitch of Coil Spring = Free Length of Spring /(Total Number of Coils-1). Spring Pitch Formula. You do so by subtracting the amount of wires in the closed coils from the free length and then dividing the result by the active coils. ω = 2πN/60 = angular speed in rads per second. It is also called a chorded coil. F. Use this Aluminum Coil Calculator to simplify estimating your aluminum coil needs. coil. For 5/8 inch tubes, the triangular pitch is 1. 307 Mpx. A voice coil motor is a simple and linear electromagnetic actuator. On top of that: 20 turns of 0. of turns 25. Unit. A coil is basically any number of turns. The pitch factors for the fundamental component, fifth harmonic, and seventh harmonic of the induced voltage for the given 3-phase AC machine are 0. Resultant pitch (Y R): Distance between the starts of two successive coils. For example, if there are 36 slots and 4 poles, then the coil pitch is 36/4 = 9 slots. P = No. Coil pitch or coil span is defined as the angular distance between the two coil sides of one coil. 4 Å observed. A curvature correction factor has been determined ( attributed to A. Typical calculation/design of the spring consists of the following steps: Set up the desired calculation units (SI/Imperial). 2e-6. Formulas. Coil Pitch. the coils should be designed such that each coil outside diameter is smaller than the coil underneath inside diamter. Add to that Kapton tape in between layers (if needed). The inner and outer radius of the planar spiral coil is determined from the general equation of the filament of the wire. Inductance is the property of the coil and tells how good the coil can store magnetic energy. The phase belt is defined as the group of adjacent coil-sidesVariable pitch springs are springs that do not have constant coil spacing. On top of that: 1000 turns of 0. This requires correction of the deflection and torsional stress values obtained by the basic formulae. The second plot is the field strength at Z=0 along the x-axis. 1416, r is the coil radius, and p is the pitch. If the coil is with no space between the pipes the number of turns can therefore be calculated as . Spring Pitch Formula. This describes the fact that a winding may consist of a number of coils, each linking flux slightly out of phase with the others. The inductance of a wire loop is a common textbook example of a circuit with inductance. Slot pitch in electrical angle is defined by (gamma = frac{P}{2}{gamma _m}) Where γ m is the mechanical angle between two adjacent slots:This study investigates the influence of stator coil pitch on the electromagnetic performance of squirrel-cage induction machine (IM) with emphasis on the flux-weakening (FW) capability for electric vehicle applications. The Neumann’s integral formula can be represented by the. The coil pitch is fixed at the slot pitch; this winding is called concentrated winding. (v) For the number of phases, m, each repeatable group consists of m or 2m-phase belts. m = multiplicity factor. Now, computing the wire lengths using 2pi x r and the. The total length of the wire used to create the coil. 10. It is always less than unity (K c < 1). In [6], [7], [8] and [9] the authors present the results of experimental study on natural. Back pitch (Y b): It is the span of the coil from the back end. Is the easy path. Therefore, the height (H) to the n (th) coil measured from the maximum coil diameter under no load can be expressed by the following formula when the pitch angle (α) is small. You do so by subtracting the amount of wires in the closed. of polesNo. . ; When the coil is having a span of less than 180° electrical, it is known as a. 9659. Since the maximum frequency is given as 100 Hz, we can calculate the coil pitch using the formula: Coil pitch = Speed / (2 * Frequency) Given that the speed is 540 km/h (or 150 m/s) and the frequency is 100 Hz, we can calculate the coil pitch as follows. Such a coil is called short-pitch (or fractional or partial pitched) coil. 5 13. The basic parameters of the coiled-coil are its pitch (periodicity of the supercoil), the associated pitch (or supercoil) angle (angle of the helix with respect to the supercoil. This calculator uses the Lorenz solenoid current sheet formula for coils having more than one turn. Draw the double layer winding layout for a 24 slot stator and 4 pole alternator 3. An alternator having 10-poles, 3-phase, and 60 Hz has 8 conductors per slot in single layer arrangement with 4 slots/pole/phase. By minimizing the metal resistance, a. If N is 100 turns, l is 6 meters. The pitch of a helix is the width of one complete helix turn, measured along the helix axis. 961. For example, if the large coil diameter equals 1. Enter the number of turns (windings). In a coil, copper tubes are arranged parallel to one another, either in staggered pattern or non-staggered pattern, along the length L of the coil. m. It is sometimes referred to as the Stationary Header. 2. 00625 in = 0. Previously, all of these dimensions were measured from centre to centre of the applicable conductors (as shown in the diagram below). This planar spiral coil inductor calculator determines the inductance of one-layer circular, square, hexagonal and octagonal planar (flat) spiral coils, which are often used in near-field communication (NFC) and radio frequency identification (RFID) tags. The induced electric field in the coil is constant in magnitude over the cylindrical surface, similar to how Ampere’s law problems with cylinders are solved. ∴ Pole Pitch = (Number of armature slots. What is the weight of a steel coil? Coils can range from 1000-60000lbs or greater, a 47in wide coil of light gauge steel about 3500 ft usually weighs in at 46000. Watch to understandPole Pitch, Full Pitch Coil, Short Pitch Coil, Coil span, Mechanical & Electrical DegreeThere are many people who want to. This distance is measured in terms of armature slots or armature conductors come between two adjacent pole centers. of height to diameter ratios, and the topic of heat exchangers of varying ratios of coil pitch to its diameter. P = No. Formula: Y R = Y b - Y f = ± 2m. The coil pitch was determined to be two times the wire. EC = EC1 +EC2 𝑬 𝑪 = 𝑬 𝑪 𝟏 + 𝑬 𝑪 𝟐 Since EC1 𝐸 𝐶 1 and EC2 𝐸 𝐶 2 are in phase, the resultant coil voltage is equal to their arithmetic sum ( Refer the figure of full-pitch coil ). Loop Inductance Calculator. Pitch Factor) To reduce weight of copper, the stator winding is constructed with a coil width less than the pole-pitch. It may even be found by applying Fleming’s Right-hand Rule. In case of a full-pitch coil, the two coil sides span a distance exactly equal to the pole. 50 x OD Vessel TL legth 3050 mm Limpet coil PCD 2700 mm Limpet coil OD 80 mm No. The winding factor is often expressed as the product of three factors: the pitch factor (also called chording or coil-span factor), the distribution factor (also called breadth, spread or zone The calculation results of , , , , and for both double-layer windings with a constant coil pitch and single-layer windings with a constant odd coil pitch are all shown in Tables 9 and 10. SP = (L-3*D)/NA SP = (L − 3 ∗ D)/N A. Back pitch (Y b): It is the span of the coil from the back end. Strictly, the length of each coil is the hypothenuse of a triangle having a base equal to the circumference of the pitch-diameter of the coil and an altitude equal to the pitch of the coil from center to center. Applicable Load InertiaSolution: To create a custom thread: Use the Coil command to create threads manually: Draw a coil with the desired settings, height, and pitch for example. In a full pitch coil, the coil span will be 180° electrical (equal to pole pitch). To eliminate the 5th harmonic voltage from the phase voltage of an alternator, the coils need to be short pitched by an electrical angle of. 29 degree. The Slot pitch at gap surface for open slots lies between 15 to 25 mm. If the blank size varies, so does the location. It is expressed in terms of electrical space degree. You can investigate three-phase integer-slot, fractional-slot and concentrated windings, both with single and double winding layers where appropriate. The downward flow isConcentrated Winding. In this paper, a simplified method for the calculation of a mutual inductance of the planar spiral coil, motivated from the Archimedean spiral, is presented. Height (H). The example shown below demonstrates how to calculate your compression spring's pitch. 953. The total length of the wire used to create the coil. As we discussed earlier that every set of windings in lap windings has no parallel paths equal to poles in a machine, so in duplex lap winding the current paths will be twice. 8 and 1. The enthalpy of a substance is the sum of the sensible heat and latent heat contained in that substance. machine has a large number of coils in slots in the armature and the distance between opposite sides of the coil is as near to a pole pitch as possible (Fig. 1588 mmThe Steel Coil Calculator can be used for Carbon Steel, Galvanized Steel, PPGI, Aluzinc Coils. whereas the coil pitch and inner diameter of L2 are exactly the. Coil pitch or coil span is defined as the angular distance between the two coil sides of one coil. The sum of the back pitch and the front pitch is nearly equal to the pole pitch of the winding. The traditional spring formula is only effective for analyzing helical springs with linear geometric properties like constant coil diameter, unchanged spring pitch and no coil contact. Therefore, for a square pitch (as if flow is parallel to the axis of the heat exchanger): [1] 2 PT π 2 o o T e d d P D π) 4. A circular coil with a cross-sectional area of 4 cm2 has 10 turns. Y f = (2S / P) - 1. 2 STEP 2 : calculate the required heat flux. 5. 1] and the type of material [1. Post Reply Tell a Friend (must be logged in) Alert Admin About Post:. the equivalent integral-slot full pole-pitch winding (with one slot per pole phase and the same number of turns as the actual winding). β is the angular distance between a full pitch and short pitch coils. The phase belt is defined as the group of adjacent coil-sides belonging to a phase, as shown in Fig. The rate formula is valid only if the pitch angle is less than 15 degrees or the deflection per turn is less than D/4. The distance between the two sides of a coil is called the Coil Span or Coil Pitch Factor. A 3 phase, 8 pole, 50 Hz star connected alternator has 72 coils in 72 slots. m = multiplicity factor. L = µ r ( n 2 . M. This is naturally equal to the total number of armature slots divided by the number of poles in the machine. A coil having a span equal to 180⁰ electrical is called a full pitch coil as shown in the figure below. Pitch Factor or Coil Span Factor is definite as the ratio of emf generated in short pitch coil to the emf generated in full pitch coil. 3 mm . Coil pitch is the centre to centre distance of the two adjacent pole. A SIMPLE explanation of Full Pitch and Short Pitch Winding. pitch factor or coil. An easy and Faster way to layout calculate length. where: SP is the spring pitch (in/coil) L is the length of the spring (in) D is the diameter of the spring (in) NA is the number of active coils in the spring Spring pitch (p p p): Refers to the space between two adjacent coils and is directly related to the free length value (L 0 L_0 L 0 ) of a spring. When this is exactly equal to the distance between the centers of two adjacent poles, 180 electrical degrees, the coil is said to be full pitch and the winding a full -pitch winding. Cite. 4 mm (i. The number of parallel paths equal to the number of. With the formula you calculate only approximately the inductance of the long coil. It doesn’t take into consideration the pitch, or slant, of the wire. After setting the coil ID, alloy, gauge, and width then alter the OD size to see the resulting coil. 3] Select the corresponding standard [1. The coil pitch of such distributed windings is normally at least three slots which brings about a high winding resistance and occupies much space for the end windings. . In a full pitched coil, the emf of two of the coil sides is exactly at 180 degrees offset. calculate the pitch of the coiled coil using coordi- nates of two pairs of equivalent residues in the two strands of the We indicate here how with a simple extension the method can be used to give the handedness as well as the pitch of the su- perhelix. Weaver’s article Numerical Methods for Inductance Calculation is used for calculations of. Spread the love. Weaver’s article Numerical Methods for Inductance Calculation is used for calculations of inductance L S: where. Therefore, the pitch should be 0. 3. I 一 the length of the coil in meters. Suppose the qualification for running and starting winding of 36 slots, 4 pole motor with running pitch 5-7-9 and starting pitch 8-10. Deg. Pitch factor is the measure of resultant emf of short pitched coil compared to the emf of full pitched coil. G = E/(2(1 + v) The pitch of the spring coil can be found by . Learn what a pole pitch is, the pole pitch formula & definition, and how to. This type of coiling design offers a number of advantages, and a wide range of products depend on variable pitch springs to deliver optimal. It is connected to one-third of the commutator bars. Since this machine has 8 poles and a pole-pitch of 48/8 = 6 slots, the coil pitch here is 5/6 = 0·833 p. Wind the new copper wire as a coil using the same gauge as the wire already on the stator. The calculation results are verified with several conventional formulas derived. What would be the formula to calculate coil/spring winding length with a constant pitch if the wire is a flat ribbon? Much appreciated. However this can be automatically converted to compatible units via the pull-down menu. In relation to pitch and length, calculate the number of turns that are required to make the helix 120 mm long if the pitch of a helical structure is 10 mm. Transcribed Image Text: 1. This is quite unfavorable due to the geometry. winding factor pitch factor distribution electrical4u web feb 24 2012 if all the coil sides of any one. Let Ss = number of stator slots Stator slot pitch yss = air gap surface/total number of stator slots = s D SFront connections 8+7=15; 30+7-30=7 8. The coil pitch was determined to be two times the wire. (2) 𝑘 𝑐 𝑛 = c o s 𝑛 α 2. Select the suitable material. Helices are important in biology, as the DNA molecule. 4. Yielding induces residual stresses opposite in direction to thoseHey Aspirants. n = number of turns. Fin height (inches) FL. This lecture will discuss;1. P=θm/pp x180 θm is the angle mechanical angle observed by the winding in degrees and Pp is pole pitch of machine in mechanical degrees P=θmP/2 x 180 Here. The opposition to. DRILL: Using a standard drill 2. Spring pitch formulas usually take into account the: Geometry of the spring; Stress; Amount of force the spring will experience; Height; Amount of coils; Density of the. across a coil will be algebraic sum of the two. through formula nes = N 2 mbnwcc n lay, (6) where bnwccis the largest integer less than or equal to nwc. No. Fo r. Steel Coil Calculator Determine Your Needs. The equation of the circular spiral coil, motivated by the Archimedean spiral coil can be described by. Pitch Factor or Coil Span Factor is defined as the ratio of EMF generated in the short-pitch coil to the EMF generated in the Whefull-pitch coil. Here is how the Pole Pitch calculation can be explained with given input values -> 0. 1. 20um away, at x=250um, the field strength is 0. Figure 13 shows the coils placed in slots. The formula for the commutator pitch in any simplex winding is given as. See morePitch Factor is calculated by dividing the coil throw (–) 1 (coil span), by the number of slots per pole. A helix, sometimes also called a coil, is a curve for which the tangent makes a constant angle with a fixed line. 5 D, the coil diameter generally changes with an increase in deflection (load). It should be quite simple, the length of one turn, following the theorem of Pythagoras is: L 1 = [ (2*pi*r) 2 +p 2] 0. 4. f. Increase the pitch of the gutter. This calculator computes all parameters ( spring rate, maximum load, maximum stress, solid height, coil pitch, coil angle, wire length, resonant frequency, shear modulus, and spring mass) related to a. Based on the arrangement of conductors, there are several types of armature winding like drum winding, lap winding, wave winding, frog-leg winding, etc. In the stator of a single phase motor, first running winding and later steering winding are put. For example, you can consider a coil with length = 1000 mm, where there are three parts: the. Commutator pitch of a progressive lap winding is yc = +1. Know Weight, Thickness and Width of a Coil, want to estimate the LENGTH of Coil. The procedure consists of these basic operations: 1. Pole Pitch, Coil Span, Back Pitch, Front Pitch, Commutator Pitch in Armature Winding of DC Machines are explained in this video. Find the frequency of the induced emf, phase emf and line emf. g. Fig. 1. The total count of pixels is found as the product of w and h: w × h = 480 × 640 = 307,200 = 0. Therefore, the pitch should be 0. Because spring pitch can be difficult and frustrating to measure on the surface of a spring, it might be best to use a formula or computer program to help you pinpoint it. So actual coil span is less than 180°. 998, and 0. lt is also known as coil pitch. 4 are the elastic modulus E, the shear modulus G=E/ 2 1+ with a Poisson ratio , the cross-sectional area A= d2/4 with a wire diameter d,The winding calculator allows you to find the optimum winding layout for your electric motor in a fast and convenient way. It should be noted that the main harmonic order of MMF is , which interacts with permanent-magnet flux linkage to product average torque. Part 2 – Inductance Calculation Refinements. In 1952, Francis Crick described a new type of protein structure, which he called the coiled‐coil 2. The coil pitch is equivalent to the span, except that this term is used more often in a theoretical context and expressed in electrical degrees, or per-unit of a pole-pitch. e. • Coils typically span into two slots in the core, so there are two coils per slot. Its value is always less than unity. Hypothetical at the time, the coiled‐coil was proposed as a solution to the X‐ray fiber diffraction patterns of α‐keratin, which showed a strong reflection at 5. 02 m) = 25CHAPTER 14. Closed and Ground. • Pitch = (span -1) × the number of rotor poles / total # of slots. The unit is kg·m2. A single-layer inductor is shown in the picture above: D c is the coil diameter, D is the coil former diameter, l is the coil length, p is the coil pitch, d is the wire without insulation diameter and d i is the wire with insulation diameter. A Fractional Pitch winding is an armature winding made up of fractional pitch coils. Coil pitch (s) is normally 2–4 times the wire diameter (d). Twist pitch (lead /) mm in. The calculator is designed to accept the total line voltage and current of the combined three cables. Coil Span Factor - Coil Span Factor is defined as the peripheral distance between two sides of a coil, measured in terms of the number of armature slots between them. 3 Winding Pitch. Formula: Y R = Y b - Y f = ± 2m. In general, it is the factor (K p or K c) by which reduction in induced emf in the short pitch coil compared to the full-pitch coil. magnet width to pole pitch ratio, efficiency, power factor, and the motor inner to outer diameter ratio, respectively. The EMF generated per path for a wave winding & lap-winding; So the generalized equation for generated EMF of DC generator is: Eg = kΦω. 2. (iv) Coil-sides are inserted into slots in a single or double layer. Though the formulas . 3 D ≤ t ≤ 0. • Winding pitch is the coil span divided by the pole. In general, coils enclosing the same perimeter with similar shapes will have approximately the same inductance. 2]. (2) θ = 2 π N. For a full pitch coil, each coil side lies under the opposite pole as shown in the figure below. In determining the total number of coils in the spring, the. The flux linked is: 2NlRBn nπ nα λ = sin( )sin( ) (21) np 2 2 Using the definition (14), the pitch factor is seen to be: nα kpn = sin (22) 2 4. This formula is equivalent to the circumference each loop of the wire makes times the number of such loops in the coil. Calculate the inductance associated with the winding using the formula L = (u0 * A * N^2)/l where u0 is the permeability of free space at 12. The basic parameters of the coiled-coil are its pitch (periodicity of the supercoil), the associated pitch (or supercoil) angle (angle of the helix with respect to the supercoil axis), and the. Within the spring design, wire diameter, number of coils, and spring free length L0 are designed for a specific load, material and assembly dimensions, or spring diameter. Consider that the Y B is the back pitch and Y F is the front pitch. 65 m2 Vessel diameter 2700 mm Pitch 1. We take as a reference frame cylindrical polar coordinate system (r, θ, z). where: SP is the spring pitch in. pole pitch5. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. The two sides of a coil are placed in two slots on the stator surface. ; The number of slots for 2 layer winding is equal to the number of coils. If the coil span is equal to the Pole pitch then it is called a full pitch coil. The values provided above are inserted into the equation below and computed. 61 m. Commutator PitchInductance. ; 1 full pitch = 180° It is denoted by K p and its value is always less than unity. Calculations are typically done using the formula: Heating Coil Capacity (BTU/hr) = Flow Rate (GPM) x Temperature Rise (°F) x 500, with. Spread the love. Example: 30+20=50/2=25 (25 is the average Diameter of coil the multiply by pi) 25x3. This advancement is measured in terms of armature conductors and is called front pitch. An advanced analytical spring model is proposed in this study to address the non-linear effects of variable coil diameter, spring pitch and coil contact that. So, the ending point of a coil in a 4 pole wave winding should be associated just beforehand or just afterward the point midway around the loop from its initial point. S = No. p - winding pitch (distance between centers of neighboring turns = the gap between the turns + wire diameter) (mm) The formula gives an error of about ±5-10%. I'm just looking for a simple expression formula for how maximum spring compression changes with free length of a coiled helical spring, say a Compression spring. Remember to incorporate the high side of the OD tolerance when examining the work in hole requirements. Using the Neumann integral formula, the expression of inductance is obtained. The right-handed helix (cos t, sin t, t) for 0 ≤ t ≤ 4π with arrowheads showing direction of increasing t. helices) is a shape like a corkscrew or spiral staircase. If the coil span is equal to the Pole pitch then it is called a full pitch coil. 2. L is the inductance in μH. What do you mean short pitch. 5)/4. 5)/4. The current direction is downwards in conductors under N-pole and upwards in those under S-pole. Therefore, the height (H) to the n (th) coil measured from the maximum coil diameter under no load can be expressed by the following formula when the pitch angle (α) is small. OD is the outside diameter. For a full pitch coil, the value of pitch factor is unity whereas for its value is also unity for concentrated coils. f. If the coil pitch is equal to the pole pitch, then it is called a full pitch coil. Back pitch should be either lesser than or greater than front pitch by 2m, where m is the multiplicity of the winding. There is a last design parameter but similarly to the pitch, it only matters to expansion/contraction springs: Spring end type: This property refers to how are the external faces of a spring. It is always 180° electrical. The following equation is used to calculate the Spiral Length. 5. Figure 4. 64 × 10 − 27 k g) ( 3. For a full pitch coil, the value of pitch factor is unity whereas for its value is also unity for concentrated coils. 966. There are two variables that specify the number of coils. per Phase: Part 1In this video, I'll give you an idea how to derive the fundamental pitch factor (coil span f. Coil-sides are inserted into slots in a single or double layer. It starts calculating the. The pitch factor or coil span factor n th harmonics is given as. The example shown below demonstrates how to calculate your compression spring's pitch. We have. For air, enthalpy is expressed in BTU/lb of. Compression springs consist of open coils (Pitch). 4” of coil / 12 = 1249. The formula for calculating the spring pitch is: SP = (L – 3 * D) / N. In electrical machine, armature winding is distributed in the slots. The coils are short pitched by 3 slots. 1 mm wire = 10 layers of wire = 1. To calculate the spring pitch, subtract 3 times the diameter from the length, then divide by the. The coils are winded according to the size of the pitch. In dc machines, the slot pitch usually lies between 25 to 35 mm. Y f = (2S / P) -1. Total diameter of the coil and winding is 515mm. A pole pitch is always 180° electrical regardless of the number of poles on the machine. This should make the AWG conversion more. The. Verify that the pitch of the spring is notA screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. The wire diameter is provided as: 3. 9. 2. I There is one coil between two commutator segments. Let, E s = EMF induced in each coil side. Pitch Factor or Coil Span Factor is definite as the ratio of emf generated in short pitch coil to the emf generated in full pitch coil. Similarly, the strength of double butt joint welding is: P = (t_1 + t_2) l sigma_mathrm {t} P = (t1 + t2)lσt. The pitch angle and pitch can vary along the helix. Front pitch (Y f): It is the span of the coil from the front end. D——parameter. Heli-Coil® Pipe Thread inserts are quickly and easily installed following the steps in the Process Sheet on p. Formulas. Assume the coil as full pitched. and 4 poles then the coil pitch is 36 4 9 slots coil span or coil pitch if the coil pitch is equal to. C p = L f / n c. Where SL is the spiral length. R = R i + a θ, θ i ≤ θ ≤ θ o. Fo r. In varying the coil pitch to examine the behaviour of the coil resistance, the coil’s width and thickness are kept constant. Based on an analysis of ohmic and eddy-current losses, we first derive an analytical formula for the metal resistance calculation of a spiral inductor. CL = (5-3) * pi = 6. The distance between each "ridge" on the twisted wire. Steam heating coil sizing involves determining the required heat output in BTU/hr based on factors like steam pressure (PSIG), fluid flow rate (GPM), and desired temperature rise (°F). The machine runs on 150V and draws 7A on that voltage. These factors represent the effect of coil distribution on the induced voltage waveform. How do you calculate the length of a helical coil? Example of using the helical coil calculator. Coil span factor or pitch factor (K p): The coil span factor or pitch factor is defined as the ratio of the voltage generated in the short-pitch coil to the voltage generated in the full-pitch coil. Enthalpy (total heat content) of air at entering wet bulb. This distance is measured in terms of armature slots or armature conductors that come between two. Common applications are screws, helical gears, and worm gears. 14159*N* (OD+ID)/2 S L = 3. 1 m due to the bending limits of the pipe. Front Pitch-The number of armature conductors or elements spanned by a coil on the front is called front pitch. Pitch can change from run-to-run if the coil feed mechanism varies in its setup or is showing wear. 2 Square and triangular pitch-tube layouts As shown in Figure 4. R1 = Ri + aq1 (5) R2 = Ri + aq2 (6) q1 and q2 are the angle of revolution of the original and its fictitious spiral coil, respectively. For a full- pitch coil α = π. Lap and Wave winding are expl. I need to find the number of turns and the wire's diameter. So we know two data sets for this coil. For the 7th harmonic, the coil pitch is, n = 7. What is the CT ratio. R = R i + a θ, θ i ≤ θ ≤ θ o. The factor of sqrt 3 3 is needed to convert between the system's phase current and line current. Note that as of the 2019-03-03 revision, you now have additional input options for coil length/pitch, winding depth/pitch and coil diameter. 0357, pitch ratio = 1, ratio of the side length of equilateral triangle to tube diameter = 0. The coil is generally shorted by one or two slots. . m. Coil Pitch (p) is the pitch or seperating distance of the coil turns, it is normally maintain equaly through out the coil. For example, if there are 36 slots and 4 poles, then the coil pitch is 36/4 = 9 slots. Though the formulas . 038) ÷ 4 = pP = number of Poles. The formula is applied to calculate the ohmic resistance of helical and spiral coils and is verified by a 2-D finite-element-method.