This angle should not exceed 6, in order that the rope may lead well on to the head sheave, and so that one rope will not grind or mount the next one in winding onto the drum. per ton is obtained. From the heating standpoint, a 600-hp. per sq. Then, 30 cars can be raised per hour, or 180 cars in 6 hours. 'It was Ben that found it' v 'It was clear that Ben found it', Correct handling of negative chapter numbers. Single-drum engines are limited to small outputs per day, or to places where the first cost of the plant is so important as to outweigh the loss in increased operating-expenses. The calculation of the size of the engines required can be made by equation 5. Related Topics . This depends somewhat on the motors that have been developed and built. = 2.616 KW or 3 KW to allow for safety. The average input to the generator was determined to be 435 hp. per cycle; this is equivalent to 1 kw.-hr. Under the heading General Data are the specifications or the information necessary before calculations can be made. Add them together. With high-speed hoisting, inertia plays a prominent part and in many cases the power required during acceleration and retardation is the dominant factor in determining the capacity of the electrical equipment. This value is assumed to represent the friction throughout the entire cycle. Portal or semi-portal bridge cranes. Lift motor with clutch system . The latest type of field control is quite a modification over the original Ward-Leonard system of control, in that the hoist-motor field is not kept at a fixed value but is overexcited during acceleration and retardation, operated at its normal value during constant speed, and underexcited during the rest period. Overhead travelling cranes - single and double-girder. It is necessary in many cases to make compromises and many additional short-cut methods can be evolved by one having to make such calculations daily. Foot 10 HP Three Phase Crane Hoist Motor, 65 Degree Celsius, 415 V. is based on the formula k = Ea/2.06 R/d + C in which. The control for a hoist motor is particularly important, since with improper control the success of the entire installation is jeopardized. The addition of the individual weights is shown on the left-hand margin of sheet No. The load diagram is determined by calculating the torque, or moment, in foot-pounds at the drum rim at the start, at the end of accelerating period, at the beginning of the constant-speed period, at the end of the constant-speed period, at the beginning of the retardation period, and at the end of the retardation period. The next two columns give the generator constant losses, including exciter losses, which must be supplied by the synchronous motor. 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. I was recently discussing with my son how it's possible to determine the power requirement of a hoist motor given only two parameters. If the hoist is one that does not drop the weight when stoppe the efficiency is less than 50%. In going through the complete set of calculations it is found that the capacity of the motor figures out 1870 hp. This friction is sometimes assumed on the basis of a certain hoist efficiency of 80 to 85 per cent. The engines would usually be direct-acting. The capacity of an electric motor depends on the temperature to which the various parts rise above the surrounding atmosphere. P = M E P = mean effective steam-pressure in cylinder in lbs. Laboratory Testing Consulting & Engineering Process Equipment. The type of electrical equipment depends largely on the nature of the power supply, its capacity, and the form of the power contract under which power is purchased. Effect of gearing When a gearbox is fitted between the motor and the drive, it has an effect on the torque, speed and inertia. 5, Fig. In addition, higher speeds are sometimes obtained by several notches of field weakening of the hoist-motor fields. Here's how you would calculate the load weight of a block of aluminum that is 6 feet long, 3 feet wide, and 4 feet tall: Volume = Length x Width x Height. At the bottom of calculation sheet No. They seldom have governing-devices, their speed being determined by the hoisting-engineer by means of the throttle, the link-motion and the brake. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The power you need is: P = M g v/n. Height of the crane:4400mm Max. 1. The iron loss, friction, and energy of the hoist motor and the iron loss of the generator are practically zero at the moment of starting and stopping. P = 60 lbs., e = 0.7, f = 0.01, g = 1, D = 8 ft., L = 4 ft., for trial. Gravity = 386 in/sec oz-in = Inertia based on weight oz-in-sec = inertia based on mass Calculation for oz-in to oz-in-sec Torque The various fixed losses not allowed for are listed under the heading Size of Driving Motor on calculation sheet No. motor. It has been the practice of the Westinghouse engineers to assume that the total friction of a hoist is based on a rope pull of 7 per cent, of the total suspended weight on the drums for single-reduction geared hoists, and 5 and 5 per cent, for direct-connected hoists. ft. of drum surface and assuming the radius of gyration at 3 in. 36 Motor temperature calculation End Inverter capacity selection (tentative) Assessment for start Assessment for acceleration (Acceleration torque calculation ) Regenerative power calculation Assessment for deceleration (Deceleration torque calculation) Power calculation Torque calculation By means of this curve, the losses at each point in the cycle can be readily determined. required = Speed (fpm) x capacity (lbs) x Percentage of uncounterweighted load (usually .4 to .5 / 33000) / overall eff. By overexciting during acceleration and retardation, the armature current is kept at a lower value, which reduces the heating effect in the main circuit. ; this permits the regulating devices on the power system to operate and produce good regulaton. and the horse-power required to raise the load will be: H. P. of load = (W + F) S/33000.(10). An a.c. motor is selected that has a 40 rating of 1500 hp. 1.5kw crane motor. stroke,, and from 400 to 600 ft. per min. Determining the FEM Hoist Duty Service Classification The calculations necessary for such a system are shown on calculation sheet No. represents the average input. If you have multiple cranes or hoists on a common conductor system: Run the 610.14 (E) (2) calculations for each crane or hoist. Portal or semi-portal cranes. Double Cylindrical Drum. However, since the motor works and stops you may reduce the required power according the duty type-see for instance IEC 60064-1 for duty type. Does it make sense to say that if someone was hired for an academic position, that means they were the "best"? C = weight of cage and car in pounds. and does not reach the maximum peak for 5 sec. One is the radius of the pulley 'r', and the other is the size of the mass. This sketch is particularly necessary when a special shape of drum is used in order that the turns and varying radius at different parts of the cycle may be shown. The flywheel loss is rather difficult to estimate and test results on existing wheels are rather erratic; the value of 20 hp. in dia. The peculiarities of the different types of engines are brought out more fully by the calculation of the size of their cylinders when equipped with the different arrangements of drums. The motor must, however, be checked for maximum load. Compared with the value obtained for the corresponding a.c. motor, there is not only a large difference in actual efficiency but also with the a.c. motor the momentary peak on the line is from 3400 to 4000 hp., depending on which a.c. motor is used, while the peak on the d.c. system is but 578 hp or a difference of 2800 to 3800 hp. Herringbone gears can be obtained with ratios as high as 15 to 1. Laboratory Testing Consulting & Engineering Process Equipment. How to use the motor torque calculator: The above tool requires the following data for calculation: Motor-rated power in HP or kW. These devices open the power circuit and apply the brakes if the speed is above a predetermined value at any point in the cycle. The maximum rope speed has been increased from 1500 ft. per min. motor may go as low as 100 hp. The difference between the ability to dissipate heat at full speed and at a standstill is greater for a high-speed motor than for a low-speed. The angular velocity is the linear speed, in feet per second, at the radius of 1 ft. (0.3 m.). Direct-acting engines should not be used for hoisting-speeds of less than 500 ft. per min., as the piston-speed will be too slow for economy. The losses, however, vary closely as the square of the load, so that to obtain a rating that will give an equivalent heating, it is necessary to determine the rating by taking into account the losses. 2. Where the power system is large and where momentary peak loads are not penalized, a synchronous motor can be used on the motor-generator set. 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. The Koepe system is a simple method of counter-balancing, and the principle could often be applied to existing plants with cylindrical drums by adding a tail-rope and an idle sheave at the bottom of the shaft, provided there is sufficient sump-room for the sheave and its slide. For this, equations 9 and 10 may be used. Where very deep mines are involved, the weight of the suspended cable will often more than balance the load, causing the power to become negative. or less. 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. Referring to Fig. Then the motor rpm will be: 43.4*34.5 =1497.3 [1500 rpm rated]. If the rest period is of short duration, the motor fields are kept excited; if the period is of longer duration, the motor fields are frequently opened which cuts down the no-load losses about 10 hp. rope on a 7-ft. diameter drum R = number of revolutions of engine per min. In order to calculate the hoisting power, you need these parameters: Then you can use this formula to get the hoisting power: $$P = \dfrac{m \cdot v}{6.12 \cdot \eta}~~[kW]$$. ), this provies all the extra juice and safety factor. We use cookies to ensure that we give you the best experience on our website. Basic Horsepower Calculations. Where power-factor correction is not desired, a simple relay could be installed; this would reduce the excitation during light load periods and increase it during heavy loads, thus tending to produce a more nearly constant power factor and saving some power. C = 5000 lbs. View Support Center, Company Resource Center, Support Let's do a quick calculation here: power = work/time work = force x distance So power = force x distance/time or equivalently, power = force x speed of lifting (rate) Force needed to hold 100 kg against gravity = 100*9.8, rounding it up to 1000N. 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. Copyright 2012-2021 911Metallurgist | All Rights Reserved, Calculations for Alternating-Current Hoist Motor, Alternating-current Hoist Motor Calculations, Calculations for a Direct-current Hoist Motor, Capacity of Alternating-current Induction Motor. ENTER THE LENGTH OF THE OVERHANG (IN INCHES) 3. The final value obtained is 610 hp., showing that a 600-hp. R = 6000 lbs. The amount of speed reduction for flywheels in service of this kind varies from 10 to 20 per cent. In the present case, this condition will be met by providing a motor with a pull-out torque of 2.5. This stress should not exceed 1/7 of the ultimate strength of the rope. This wheel will have a thickness of 7 in. Products The calculations for an a.c. motor are given in hoist calculation sheet No. How much higher depends on electro-mechanical aspects. Aluminum weighs 165 pounds per cubic foot (based on the numbers from the table above). The maximum rope speed has been increased from 1500 ft. per min. At any time during the cycle that the load on the hoist motor is above this value, the flywheel will supply the surplus, while if the load is below this value, the flywheel will store up energy keeping practically a constant load on the induction motor. f = coefficient of friction. According to table, hoist group FEM 3m. From the hoisting cycle, the kilowatt-hours per ton and the overall efficiency of the hoist can be estimated, as shown under the heading Input with Rheostatic Control. will range from ten to fourteen poles; from 200 to 600 hp., fourteen to sixteen poles; and from 600 hp. per ton of coal hoisted. ; Fan Motors - Starting Torques - The motor must be capable of accelerating the fan wheel to it's operating speed. These forms have been modified from time to time, in accordance with suggestions by various engineers. and 0.925 kw.-hr. The generator field varies with the speed and, by means of a comparatively new type of relay, the acceleration and retardation is entirely automatic, during which time the main armature current is held at a predetermined fixed value. 1. 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. Hoist 22.5m Max. 1 in. If a rope of lighter weight is desired, a plow-steel rope could be used instead of the cast-steel. After this the thickness of the rope can be found by equation 13. If there is any doubt, contact CraneTec. 2, Fig. These together make the dead load, C, equal to the weight of the ore, O. t = thickness of rope in inches, rev2022.11.3.43003. There has been considerable argument regarding time used in a calculation for capacity. Calculations. W= (R + C + O) C = R + O, and Appointed Person Calculation Template - Ritchies Offshore Services 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. It would, of course, be possible to develop a special motor having very much less inertia than either of the motors shown in Figs. However, air compressors are much more available as compared to hydraulic power . The load cycles for both alternating-current motors are plotted in Fig. End 2300mm Crane Work DutyA8 Mechanism Work DutyM8 Unit as follows if no specified in the design calculation: Force, Weight: NKg Length: mm The horsepower-seconds during each portion of the cycle is readily obtained by taking the average value and multiplying by the time. 8. F = 4 x 16 x 3 = 192/h which is < 300. With these classes of engines the piston-speed may be taken at 200 to 400 ft. per min. diameter, which gives a cylinder with better proportions. at throttle, corresponds to a cut-off of about . This means that the motor can be ENTER THE LENGTH OF THE TRUCK BED (IN FEET) 2. To calculate the remaining safe working period (SWP) of your hoist you can use our free SWP Calculator or it can be calculated using this formula. 3. for those with 24- to 72-in. Instructions: Select the number of phases from the drop-down list Enter the motor rated voltage in volts (V) Enter the motor power rating and select the appropriate unit (HP or kW) Enter the power factor and efficiency of the motor
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