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  1. 1 point
    DrD

    Determine Motor power

    If you are looking for steady operating power, the SumTorq = I * alpha does not help. In steady operation, all of the power input must be converted to heat. Where is it going? What are the torques that act on the system in steady state? Perhaps some viscous drag? Is there a brake? Is there a friction rub? Find these and figure out how much power they consume at operating speed. That is the required input power.
  2. 1 point
    Dear Engineering forum, I have a particular problem and I am hoping that the larger engineering world could help me. I will do my best to describe all of the important factors and answer any questions. I do not necessarily expect anyone to solve it straight away (although it would be convenient) but, giving me some ideas as to what I could test for or look out for would be fantastic. Situation: I have a 22kw electric motor driving a centrifugal pump at approx. 45% load pumping at 25 - 30 m3/hour, The electric motor is driven by a Variable Flow Drive (VFD) manufactured by ABB, which in tern is controlled by a PLC, The inlet of the pump is connected to a 20,000ltr tank, The outlet of the pump is connected to 4x pressure vessels maintaining 200kPa (2 bar) for high pressure delivery to an open outlet, The speed of the pump is determined by maintaining the pressure on the outlet of the pump The pump has the usual wire strainers, butterfly valves for maintenance and pressure indicators after the pump (no indicator installed before pump, will be occurring in the next couple of days) The Problem: My motor/pump keeps shutting down during its cycle (while it should continue pumping) The VFD gives me a "Over current" fault warning as a result of the shut down. This usually occurs a couple of hours after the fault is cleared and pumping has resumed operation. The IMPORTANT facts: I have personally witnessed the motor/pump shut down momentarily (stop for 1sec before commencing operation) multiple times before the complete shut down and the "over current" fault is given, like it is tripping the power switch, Every time the fault has occurred, the VFD records current supply anywhere between 7 - 21 amps, RPM at 0, Hz at 0 (the motor is rated at 27amps) My industrial qualified electrician assures me that there are no irregularities in connection or communication, everything checks out electrically that he can test for. I have dismantled the pump and there are no signs of excessive wear, plus during operation there is no odour, no strange noises and no excessive vibration, Neither the pump nor the motor are showing any leaks, signs of rust or any other obvious sign of degradation at least on the outside. The pump and motor have been running continuously (approx. 22 hours/day) without problems for 3.5 years. The pumps mechanical seal was only replaced 6 months ago and periodic maintenance is always kept up to date. The pressure and flow rate on the line following the pump obviously drop every time the motor shuts down for that 1sec but there are no other changes during operation. The water that is being pumped is particularly brackish (salty), but has been filtered multiple times so contains no particles or other additives. I have a globe valve that I use to limit the flow rate by applying back pressure, which is of course is maintained at 200 kPa which is when the VFD comes into play. I have no reward to offer for the person with the suggestion that leads to the cause, other than the pride of having the knowledge the engineering forum experiences for the solution and that you really helped out a fellow engineer. Regards RyanTW
  3. 1 point
    mehlam hamid

    Determine Motor power

    Thankyou DrD for replying, well let me describe you the procedure : i)The process department defines the tip velocity & OD of the rotor required to process a substance. ii)So, Well get the required RPM of the rotor (v=rω) ,and we need the rotor to run steadily at this rpm iii)Rotor Design is Confirmed, and say I find a rough MMOI ....................................................................................................................... Now, How do I find the Power Required to run the rotor steadily at say 1400 RPM?? And I do know that a high initial torque is required to get the rotor from 0 to 1400 RPM, How to find this initial Torque?? I did try using T=I(moment of inertia) x α(angular acceleration) I know the MMOI , and α = dω / t where dω will be 2*pi*(1400-0)/60 Now here's the problem HOW ON EARTH WILL I BE ABLE TO GET THE TIME 't' ??!
  4. 1 point
    DrD

    torque for 3 roll bending machine

    This is a really tough question because plastic deformation is involved. In forming a ring this way, the material must be permanently deformed (partially moved into the plastic state) so that it does not spring back. I suspect you might make some FEA calculations, but the ultimate proof is in the testing. I think I would opt to go straight to testing. DrD
  5. 1 point
    Steve Beck

    PRESSURE SENSOR

    Depending on the strain gauge technology the output can vary from 1 to 3 millivolts per volt (mV/V) to as much as 10 to 30 mV/V. To calculate your full scale output, you would multiply the output of the sensor by the voltage used to power the device.
  6. 1 point
    mechebus

    SOLIDWORKS

    hello! I'm new in this website and I'm studying mechanical engineering still. I want to improve myself about designing. So can you help me some solidworks examples that I can work on it. thank you even now.
  7. 1 point
    Zane

    Homemade metal bender

    Interesting tutorial video, thanks for sharing it. I love making things, so this will come in useful.
  8. 1 point
    DrD

    Wind Load capacity

    It would help if you posted a picture of the situation with dimensions, wind load direction, etc. DrD
  9. 1 point
    Without a thermostat, the engine block would swell and shrink as the temperature varies with load. This would make the pistons wear quickly and irregularly. Ever notice how an engine is somewhat noisier when it is cold that when it is at operating temperature?
  10. 1 point
    Duke Vishnu

    SOLIDWORKS

    Soildworks is the primary modeling software which is used in many industries and R&Ds . So first you need to learn basic part modeling regards Mechanical Designs you can google some of designs improve in that and later .Try to assemble the part and Draft the each part with annotation and dimensions
  11. 1 point
    It is a control device which keeps/brings ur engine on normal operating temperature very quickly to keep engine performance smooth and safe
  12. 1 point
    1. pressure represent intensity of external forces acting at a point. but stress represent intensity of internal resisting forces develop at a point.2. pressure is always acts normal to the surface. but but stress may also act either normal or parallel to the surface.3. magnitude of pressure at a point in all direction remain same. but magnitude of stress at a point in all the direction are unequal.4. pressure can be measure by using measuring device.like pressure gauge. but stress can't be measure directly by using any device.
  13. 1 point
    It is basically a regulator when the temperature of surrounding is low then the efficiency drops so that to attain a high temperature it will cut off the cooling water supply once the engine attains certain high temperature it will again supply cooling water.
  14. 1 point
    Thermostat is used as a gate in cooling system. When coolant temperature increase more then 85 degree Celsius then its opening slowly and allow coolant to go to top tank of the radiator then further process going on.
  15. 1 point
    VKT0526

    Differential used in automobiles

    A vehicle with two drive wheels has the problem that when it turns a corner the drive wheels must rotate at different speeds to maintain traction. The automotive differential is designed to drive a pair of wheels while allowing them to rotate at different speeds. In vehicles without a differential, such as karts, both driving wheels are forced to rotate at the same speed, usually on a common axle driven by a simple chain-drive mechanism. When cornering the inner wheel travels a shorter distance than the outer wheel, so without a differential either the inner wheel rotates too fast or the outer wheel drags, which results in difficult and unpredictable handling, damage to tires and roads, and strain on (or possible failure of) the entire drivetrain. In rear-wheel drive automobiles the central drive shaft (or prop shaft) engages the differential through a hypoid gear(crown-wheel and pinion) the crown-wheel is mounted on the carrier of the planetary chain that forms the differential. This hypoid gear is a bevel gear that changes the direction of the drive rotation.
  16. 1 point
    My point . cylinder and piston in between some amount of cap we give it's uses for free move piston up and down . and assembly process also it used . now the given cap compression time leack the air fuel mixture it's create lack of compression so we uses ring leack stop and oil ring it's down eng cooling oil not mixed with air flue it's help .. And sorry am not good in English any mistakes forgive
  17. 1 point
    Asim Mehmood

    reason for three rings in a piston

    Each ring is an expansion-sprung ring, but with a gap. By using 2-3 rings, and then alternating the locations of the gap, a complete seal can be made for when the piston moves upwards on both the compression stroke and the exhaust stroke and during combustion.Higher compression engines will sometimes use 4 rings to further the sealing ability.
  18. 1 point
    Umair Zaheer

    reason for three rings in a piston

    Piston rings commonly used on small engines include the compression ring, wiper ring, and oil ring. A compression ring is the piston ring located in the ring groove closest to the piston head. The compression ring seals the combustion chamber from any leakage during the combustion process. When the air-fuel mixture is ignited, pressure from combustion gases is applied to the piston head, forcing the piston toward the crankshaft. The pressurized gases travel through the gap between the cylinder wall and the piston and into the piston ring groove. Combustion gas pressure forces the piston ring against the cylinder wall to form a seal. Pressure applied to the piston ring is approximately proportional to the combustion gas pressure. A wiper ring is the piston ring with a tapered face located in the ring groove between the compression ring and the oil ring. The wiper ring is used to further seal the combustion chamber and to wipe the cylinder wall clean of excess oil. Combustion gases that pass by the compression ring are stopped by the wiper ring. An oil ring is the piston ring located in the ring groove closest to the crankcase. The oil ring is used to wipe excess oil from the cylinder wall during piston movement. Excess oil is returned through ring openings to the oil reservoir in the engine block. Two-stroke cycle engines do not require oil rings because lubrication is supplied by mixing oil in the gasoline, and an oil reservoir is not required.
  19. 1 point
    The thermostat regulates the temperature of the engine. When it is fully open the coolant flows from the engine block to the radiator and to maintain temperature when its closed the circuit to the radiator is off. It's usually located in the upper section of the engine block
  20. 1 point
    Its a valve. It is located in the cooling circuit, between the engine and the radiator. If it opens it allows flow of water, assisted by a water pump, to take place from the block to the radiator in order to allow the block to "give up" excessive heat. It is a self regulating device and it is calibrated to open at a particular temperature - usually about 95 degrees C. It has a hysteresis also, that is a gap between the open and close temperature due to mechanical friction within the device itself and therefore after cooling has taken place it may not close again until the temperature drops to 90 degrees C - a hysteresis of 5 degrees C. So in this example, when the engine gets to temperature, it should maintain an operating temperature of between 90-95 degrees C. Why is this important? It is critical for a couple of reasons, firstly the many machined limits and fits of critical moving parts are designed with the prescribed operating temperature in mind. Secondly, and maybe more critically, the lubricating oil viscosity is too thick at low temps and too thin at higher temps. Oil breaks down rapidly when subject to too high a temp and closely machined mechanical parts experience boundary lubrication - that is metal to metal contact. Probably the best way to screw up your engine is to allow it to overheat! Irlanski
  21. 1 point
    There are two reasons why cooling is required in I.C. Engines. Heat is produced due to burning of fuel inside the engine. Due to heat, thermal stress develops in the engine components. This results in unwanted change in shape (Expantion and contraction). For proper funtioning the moving components should be in there desired shape and size. Other important reason of cooling is for proper lubrication. Yes, due to excess heat the engine oil looses its vicosity and the moving components will not get proper lubrication. Every fulid have a boiling point. At a particular temprature it starts to convert into vapours. Without cooling piston, Bigend, Smallend, crank bearings,Cam, Valves and other mating parts will sieze.
  22. 1 point
    Arpit.v

    What is bulk modulus of elasticity ?

    Modulus of elasticity or young modulus is ratio of stress to strain. Simillarly Bulk modulus is the ratio of Volumetric stress to volumetric strain. Volumetric Stress is the normal stress acting over whole volume of the body. Volumetric Strain is the ratio of change in volume to original volume.
  23. 1 point
    Welcome to the forums Avaya Sahoo :)





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