hoist motor calculation

In going through the complete set of calculations it is found that the capacity of the motor figures out 1870 hp. The first element of the problem to be determined is the load to be raised. When work is done by a source of torque (T) to produce (M) rotations about an axis, the work done is: radius x 2 x rpm x lb. C = 5000 lbs. About Hoist Monitoring Hoist monitoring protects your equipment from overloads while providing you with accurate real-time information about how your equipment is being used. [minimum motor 9.28 kW/1500 rpm.]. With double conical drums, the work on the engine is kept constant by giving the cage at the bottom the short leverage of the small end of the drum, and the cage at the top the longer leverage of the large end of the drum. The gears cost about $3000 each, besides the labor of replacing and the loss of 24 hours in changing the old for a new one. If the mass of the load (blue box) is 20 Newtons, and the radius of the pulley is 5 cm away, then the required torque for the application is 20 N x 0.05 m = 1 Nm. Referring to Fig. The windage and friction of the generator are fixed, values, estimated at 15 hp. A real-life Venco Venturo team member can point you in the right direction. The flat-rope system is very largely used in Montana, and in some other districts which have followed the Montana practice. The piston-speed is 522 ft. per min. This method may result in considerable error during the high-speed portion of the cycle, where the actual load on the hoist motor is very low and when the friction load is really at its maximum. In order to better illustrate the value of the method, examples are given showing the determination of the electrical equipment of an alternating- current hoist, a direct-current hoist with flywheel motor-generator set, and a direct-current hoist with a synchronous motor-generator set. You will learn how to determine the lifting velocity from the motor velocity, as well as. 4 is used to determine the load cycle and capacity of the hoist motor. This total weight is suspended from the drum rim so that the radius of gyration is the same as the drum radius. The following example presents one method of computing this torque. Laboratory Testing Consulting & Engineering Process Equipment. We use cookies to ensure that we give you the best experience on our website. Cable Size Calculation of 125 Kw LT Motor Motor KW = 125 Pf = 0.8, Efficiency = 94% System Voltage, V1 Cable length = 200 m Load Current = P / (1.732 x V x Pf x Eff) > (P = 3 x Vx I Cos = for three phase circuits) = 125000 / (1.732 x 415 x 0.8 x 0.94) ~ 230 A This is the full load current cable needs to cater in Ideal condition. While knowing these calculations is a good way to get a sense of the size of the motor needed and a ballpark for what stall . Load The maximum load to be lifted 22,000kgs + Load 1,500kgs 3. 3, which shows that the cycle must be made in 21 sec. Under the heading Inertia, the inertia of the various parts is determined based on the drum radius. The rated power factor of the motor. In the foregoing case, the average load, upon the motor is 450 hp. n = number of layers of rope in coil. Pneumatic motors are expensive and very loud as compared to hydraulic. The motors begin their cycle of lifting the leaf through a reversing starter and an accelerator resister bank begins to come on line by closing one of 4 sets of contactors in a sequence of about 2 seconds apart. If you have different units than those used in the relationships above you can download the units converter that I developed some months ago. Calculation sheet No. Height of the crane:4400mm Max. This value is assumed to represent the friction throughout the entire cycle. instead of 30 sec. The relays are so sensitive that the usual variations in current due to notching are entirely absent. 0.4kw crane motor. Our accessories, body packages and van cranes are also a boon to productivity. All the info provided in earlier answers covers this. A high-speed motor will be cheaper and have a better performance, with regard to efficiency and power factor, than a low-speed motor. With flat rope, d = 1/6 the thickness of the rope, and C = 27.54. Direct Acting:Single Cylindrical Drum. Looking at Figure 430.1 in the NEC will help you keep this distinction clear. The crane duty motors are specially designed to offer satisfactory performance and long lives for service on the cranes and hoists. y= diameter of coil of rope, when cage is at the top, in ft, Does it make sense to say that if someone was hired for an academic position, that means they were the "best"? On two speed hoists, the slow speed is generally one-fourth the hoist main speed. 5, Fig. At the top of the sheet are four columns, the items in the first, which is headed Hoist-motor Output, are obtained from the load cycle on calculation sheet No. ENTER THE LENGTH OF THE TRUCK BED (IN FEET) 2. This is considered later in determining the capacity of the synchronous motor, which is part of a motor-generator set. ~= as user58220 said. The capacity of the generator will be close to 1000 kw. Can an autistic person with difficulty making eye contact survive in the workplace? In general, the drums should be as small in diameter as good rope practice dictates, for the smaller the drum diameter the greater will be the speed, which will permit of a fairly high motor speed or a lower gear reduction. The no-load loss of the set is 74 hp., or somewhat larger than with the flywheel set; as the synchronous motor is much larger than the induction motor, its losses, including excitation, more than make up for the flywheel loss with the induction motor set. Typically around 0.86. 5, Fig. This gives a cylinder 26 1/8 in. All loads on the generator are directly transmitted and must be supplied by the synchronous motor, while with the flywheel this was not directly the case, since the flywheel takes care of all peak loads and sudden fluctuations. FLA - "Full Load Amps" - amount of current drawn when full-load torque and horsepower is reached for the motor.FLA is usually determined in laboratory tests.Note! The shaded part of the accelerating portion of the cycle indicates the power loss in the rheostat; this loss is unavoidable when rheostatic control is used. It is usual to place the drum far enough back from the head sheave to keep the fleet-angle within the limit; but where it cannot be done, it is necessary to guide the rope onto the head sheave and onto the drum by rollers or sheaves running on vertical spindles. Overhead travelling cranes - single and double-girder. Koepe System. Calculation sheet No. Hoisting machine eff. 2, which also shows the rope speed, kilowatt-hours per ton, and other information in regard to the hoist. Fan/compressor motors. How much higher depends on electro-mechanical aspects. The ideal case would be one in which the work of hoisting was constant at every part of the hoist; but the thickness of the rope may be such that the leverage of the load increases faster or slower than the weight of the load decreases, thus making the work on the engine to vary daring the trip. This means that the operator has electric control of the hoist at all times, which is much safer than to depend on mechanical brakes in cases of emergency. If electric braking is used, the entire area of the quadrilateral representing the retardation period will be lost in the rheostat. Effect of gearing When a gearbox is fitted between the motor and the drive, it has an effect on the torque, speed and inertia. The result is 435 hp. The size of the rope fixes the minimum diameter of the. is based on the formula k = Ea/2.06 R/d + C in which. Conductors for a single motor must have an ampacity of not less than 125% of the motor full-load current rating. Outrigger Load Point load = (1+2) x 100% = (50,000 + 23,500) x1 = 73,500kgs or 73.5t. Placing these equal to each other, (W + F) D/2 =(P x A x e)L/2. Let's say the reduction ratio will be 34.5. This means that the motor can be Let us assume the same set of specifications, except that the output per day is 3000 tons. There's lots of other stuff such as temp requirements/ frequency of switching cycles, number of lifting cycles to be considered. From equation 13, knowing t, the value of y can be obtained, or having decided on y, the equation can be solved for t. The minimum diameter of the barrel, D, depends on the thickness of the rope, and can be calculated from Mr. Hewitts equation, previously given : k = Ea/2.06 R/d + C in which k= bending-stress in pounds, E = modulus of elasticity = 28,500,000, a = aggregate area of the wire in sq. The development of this motor, however, would probably cost several thousands of dollars, which would make it non-competitive. The motor is 12-years old and has not been rewound. They are always geared and provided with a flywheel on the crank-shaft. The third and fourth columns are headed Generator Input, the third being the apparent input and the fourth the real. for fast coal hoists and 10 to 20 sec. If the shaft is inclined, the stress in the rope due to the weight hoisted will vary with the sine of the angle of inclination, thus: K = (2 W + R) sin x + F,. The liquid rheostat is used to some extent in connection with a.c. hoists. Multiply this sum by the appropriate demand factor from Table 610.14 (E). (329 m.) and the cycles approach 3 per min., the application of an a.c. motor to a hoist becomes questionable. Referring to Fig. The best way to obtain the variable losses is to plot a loss curve for the particular motor, as shown in Fig. R = weight of rope in pounds. The electrician makes the following measurements: Measured Values: V ab = 467V I a = 36 amps . Looking at Slip (Rotational speed)/ torque curves should note that the hoist motor will be selected to work at >=96% slip at the max load. This type of rheostat makes the best showing with the larger a.c. hoists and where, the cycle is not too rapid. The third column is obtained by adding the variable losses of the generator to the values in the second column; that is, the copper and iron losses. The high-speed motor, on the other hand, requires a high gear ratio and the equivalent inertia at the drum rim is very high. These motors may also be used for similar applications such as material handling, sluice operation on dams/weirs, lifts . Copyright 2012-2021 911Metallurgist | All Rights Reserved. Most induction motors are designed to have a pull-out torque of twice the full-load torque. Single Phase Hoist Duty Motors, Voltage: 380 - 415 V. 10,000. 4, Fig. F = friction in pounds, f = coefficient of friction. The total minimum weight on each leg (1,000 pounds) times . 5 contains blanks for normal speed of set, diameter of flywheel, etc. The flywheel loss is rather difficult to estimate and test results on existing wheels are rather erratic; the value of 20 hp. 2,000 pounds divided by 2 legs equals 1,000 pounds of total minimum weight on each leg of the sling. or 2 TM. ; an economic speed for this capacity is 720 r.p.m. With the foregoing information, which has involved calculations of the simplest nature only, the load at various points in the hoisting cycle can be determined, as outlined under the heading Load Diagram. A motor is selected that will probably be of sufficient capacity so that the inertia of the rotor can be estimated. The amount of speed reduction for flywheels in service of this kind varies from 10 to 20 per cent. If the average speed of hoisting is kept at about 2/3 of this maximum, the average speed will not exceed 600 ft. per min. Having settled the size of the useful load to be hoisted, the size of the rope must be determined. They are thus more economical to operate than a single-drum engine, and the cost of installing will probably not be over 50 per cent, greater than for a single-drum engine. In many cases it is necessary to plug the motor to obtain the proper rate of retardation. The more a machine or hoist is used, the sooner it will wear out. Thus the weight of the rope in the two compartments is exactly equal, and the whole hoisting mechanism is in balance at all points of the trip. These two parameters are the weight to be lifted (150 kilos),and the speed at which they are to be lifted (3 meters per second) It is often necessary to calculate the size of a mine hoisting system required to raise a given quantity of material, either as a preliminary to the detail design of the machinery, or to decide whether machinery on hand or offered by a manufacturer is adapted to the work to be done. wound for 2200 volts, three phase, 60 cycles, twenty pole. motor is required and also indicating that the average value in this case must be increased by 33 1/3 per cent, to obtain the correct value. By using the same speed or possible a somewhat higher speed motor, the total inertia may be considerable, less by the use of two motors. These together make the dead load, C, equal to the weight of the ore, O. Lifting Height: Main Hoist 20.5mAux. = 13,080 lbs., and ultimate strength of rope should be 7 X 13,080 =91,560 lbs., which would require a 1-inch- diameter flexible cast-steel rope, having an ultimate strength of 100,000 lbs., and weighing 2.45 lbs. d = diameter of piston in inches, 3,700. Thus the available strength is only 1/9 of the ultimate. These values are obtained by adding the variable losses of the hoist motor to the output values in the first column. The small cylinders make the first cost lower than that of a direct-acting engine; but the gearing for large hoists is a serious objection. motor may go as low as 100 hp. The calculation of the size of the engines required can be made by equation 5. 5. The resister bank contactors remain closed until the leaf is in full upright position. The capacity obtained is based on reversing the motor to obtain retardation. From Table II. 3-phase motor amps calculation with power rating in kilowatt (kW): In most cases it is better to install a complete new hoist than to attempt to use old mechanical parts. dia., 3 in. Here the friction is also affected by the slope, and varies with the cosine of x, or F = f (W+R) cos x; f may be taken as .02. Taking L = 4 ft. for a trial and substituting in equation 5 to find the size of cylinders. If this value is divided by 550, the result will be horsepower. Thus the entire weight of the hoisting mechanism is in perfect balance at all times, and the engine only has to raise the weight of the ore and overcome the friction of the moving parts. A steam engine has a definite maximum torque, which the hoist has been designed to withstand, while a motor may be able to deliver momentary torques beyond the strength of the mechanical parts of the hoist. 7, which indicates that the total power to be absorbed is 7071 hp.-sec. It is interesting to compare the sizes of the three types of engines, hoisting the same load at the same speed. Then, for a single-drum, direct-acting engine, Fig. At the instant of starting, the power in one cylinder acting on the crank, in the top or bottom position, must have a moment equal to or greater than the moment of the unbalanced load pulling from the circumference of the drum. by 24 in. With the d.c. field-control system, the speed of the hoist follows the control lever irrespective of the load and drifting cannot occur; this makes it possible to apply safety devices that would not be effective with an a.c. hoist, also to apply automatic control, which can be made to function without the use of an operator. It is frequently desirable to know the no-load loss of the motor-generator set or the power required to drive the set during the rest period. plicated than the control for one, but the cost of the entire installation may not be any greater than when using one large motor of a capacity greater than the combined capacity of two motors. How to align figures when a long subcaption causes misalignment. instead of 30 sec. Reels for flat rope. They are not adapted for regular mining work on a large scale, as the work expended in raising the cage, car and rope, each trip, would exceed the work of raising the ore. Double-drum engines overcome the dead-work of hoisting the ore-carriers by balancing the weight of the cage and car in one compartment against those in the other. motor. Rlvt goods lift motor, for industrial, 4000rpm; 0.25-7.5 hp,0.16 hp to 30 hp three phase helical geared moto. If the original diameter of the barrel of the reel and the thickness of the rope are properly chosen, the moment of the resistance will be constant. The real values are substituted in the fourth column and consist of the copper losses of the hoist motor and generator. and the peak during retardation is a little over 2100 hp. Where a new hoist is to be installed, the designer of the mechanical parts can readily take care of the maximum stresses likely to be imposed by the motor. There must be a division left between the ropes on a conical drum in order to furnish positive grooves for the rope, so that the large coils cannot slip down over the smaller ones; hence the drum must be longer than those of the cylindrical design, even when the mean diameter of the conical drum is the same as the diameter of a cylindrical one. For this, equations 9 and 10 may be used. v = velocity in m/s. The small values at the end of the retarding period and during the rest period are neglected, as their effect on the heating is negligible. For such high rope speeds and rapid cycles, the inertia effect of the a.c. motor is great, the power loss during acceleration and retardation, high, the peak loads upon the power system in some cases prohibitive, and the braking system questionable. I've focused on 'Power required to lift at a speed' as this addresses the original intent of the question. O = 5000 lbs. The actual work done is designated as shaft horsepower-seconds and is the product of the weight of the coal by the depth divided by 550; the efficiency, as shown, is 37.5 per cent. Determining the piston-speed by equation 8. Thus the work on the engine is kept constant, when the rate of increase of leverage and decrease of weight are in inverse proportion to each other. The hoist runs for one out of every 100 minutes, so its duty cycle is expressed as 1/100, or 1 percent. The efficiency of the motor. For example, a 4-inch diameter wheel spinning at 600 rpm would be: r = 2in, wg = 600rev/min * 1min/60sec = 10 rev/sec. stroke. stroke,, and from 400 to 600 ft. per min. The same applies to the retardation portion of the cycle, except that when electric braking is used with an a.c. motor all of the power represented by the quadrilateral is drawn from the line and wasted in the rheostat. Double Cylindrical Drum. = 100 lbs., D = 7 ft., P = 60 lbs., g = 1, f = .01, e = 0.7, L for trial = 4 ft., to find diameter of cylinder. Pump motors. The friction of the hoist parts, including windage and friction of the cages in the shaft, has been the subject of much controversy. In the following discussion the loads will be considered as being hoisted from vertical shafts, as the principle remains the same for both classes, the only difference being that the stresses in the rope and on the engine and other parts of the machinery change with changes in the slope.

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hoist motor calculation

hoist motor calculation