WhatsApp)
These nonsinusoidal quantities (voltages and currents) can be divided into sinusoidal components, the fundamental frequency ( 50 or 60 Hz) component and the harmonic components. Figure shows the harmonic spectrum up to the 50th order of the "Trapezoid" shape AC current of Figure (a) as a percentage of fundamental current.
Ball Mill SAG Mill Figure 2 Core pressing system with spring plate/washer and retightening statistics in a typical installation Access to the inside of the motor and the cooling system The easier the access to the inside of the motor is, the more convenient and efficient is the work on the motor.
83 Centrifugal force outward Fc mp 2 Dm 2 () is the angular velocity, mp is the mass of any particle (media or charge) in the mill and Dm is the diameter of the mill inside the liners. Gravitational force Fg mpg () The particle will remain against the wall if these two forces are in balance ie.
Feb 23, 2018· High noload current: Motor not rewound. One situation in which higherthanexpected noload current can occur is with reconditioned motors. Although some motors with noload currents above or below the guidelines shown in Table 1 may still be satisfactory, motors with noload current outside of these ranges warrant further analysis.
COPPER MOUNTAIN: OVERVIEW ON THE GRINDING MILLS AND THEIR DUAL PINION MILL DRIVES ... the accuracy of the load sharing between the two motors. KEYWORDS SAG mill, ball mill, ring gear, dual pinion, drive systems, variable speed ... a short circuit on the motor terminals that could cause severe damage to the gear, pinions, bearings and mill. ...
lines), the motor is at risk of tripping due to high current, depending on the conditions. Safe operating of a mill and motor means that the process lines should appear below the red and blue lines across the whole range of speeds that are of interest. In this example (13% .
There are several factors which cause a voltage sag to happen: Since electric motors draw more current when they are starting than when they are running at their rated speed, starting an electric motor can be a reason of a voltage sag. When a linetoground fault occurs, there will be a voltage sag until the protective switch gear operates.
THE LOW SPEED MOTOR SOLUTION Due to the high torque required by the mill, low speed motors are generally synchronous machines. The mill is a low dynamic system therefore a brushless synchronous machine is best suited for this application. Brushless synchronous motors have no wearing parts, and the AC/ AC excitation power is kept small.
the motor must be able to supply the proper voltage and current (amperage) 8) Junction Box Inspect the 12 motor lead connections, a loose connection will cause intermittent Over Current faults. The motor "boltclamp" connector insulation has been known to wear and cause intermittent shorts to GND.
Apr 01, 2018· Motor Starting Current: Induction motor starting on full voltage (also known as across the line starting or direct online starting) has the undesirable effect of drawing five to ten times or more of motor full load this starting current of induction motor persists till the motor reaches close to its synchronous speed (rated speed).
Apr 01, 2003· Overheating Electric Motors: A Major Cause of Failure. EP Editorial Staff | April 1, 2003 ... Even though the motor current may vary when applying overvoltages, the excessive damaging heat in the motor will not improve. ... Chemical abrasive substances in the air, wet operation, and high altitude operation are a few common environmental ...
avoid motor overheating due to frequent starts. DC Field Current Loss Protection Option. This feature trips the motor when field current drops below the programmed . setpoint after the motor has synchronized. To utilize this feature a DCCT and Field Current Calibration Module must be ordered with the SPM. Reduced Voltage Starting
motor inrush current. • The type of motor selected affects the inrush current in the motor circuit. Induction and synchronous motors have different reactances and inrush currents depending on the number of poles/speed of the motor. Another factor in the selection of the starting method is the voltage drop permissible at a given location.
Electrical equipment; especially motors and their controllers; will not operate reliably on unbalanced voltages in a 3phase system. Generally, the difference between the highest and the lowest voltages should not exceed 4% of the lowest voltage. Greater imbalances may cause overheating of ...
What are the most common causes of electric motors failure? ... greatly impact the motor. To avoid an overcurrent, there are some devices that need to be installed that can prevent it from ...
Jun 22, 2009· The failure of the SAG mill motor follows a failure in March of one of two identical ball mill motors. The spare motor carried in the Operation''s store was used on that occasion to minimise downtime. The motor damaged in March is expected to be repaired and returned to site in early July.
The fact is, numerous reasons can exist which causes a motor to trip that will not be seen by a Megger, such as a turntoturn short. Breakdown in the insulation between individual turns of a winding can occur inside a stator slot or at the end turn and be completely isolated from ground. ... These high zero sequence currents return to the ...
Voltage sags – or dips which are the same thing – are brief reductions in voltage, typically lasting from a cycle to a second or so, or tens of milliseconds to hundreds of milliseconds. Voltage swells are brief increases in voltage over the same time range. Longer periods of low or high .
Cause: The common cause of this disturbance is switching on of the heavy appliances like motor or refrigerator or Air conditioner which require large start up reasons can be failure on the power lines and transformers. Prevention: Like surges, sag can be prevented by using voltage regulators and power conditioners.. BROWNOUTS. A brownout occurs when there is a steady decrease in ...
Q: For now I am working on a mining project which involves starting two SAG mills, the method of starting these mills is by rotor resistance and likewise we are using an energy recovery system (SER), could someone tell me how this system works SER? Each mills have two motors of 8000 kW at kV.
causes of high current on sag mill motors 6761 Ratings ] The Gulin product line, consisting of more than 30 machines, sets the standard for our industry.
In my opinion, current imbalance on motors of a twin Pinion Mill Drive train is caused by inaccurate load sharing. Power supply to the motor has no effect as it is passive and power is drawn as needed. Since this is a WRIM and LRS set up (no VSD with active load sharing or Quadramatic) the motors rely on natural load sharing.
sense to consider using VSDs with standard Squirrel cage motors on mill applications. When using a VSD to run an ac induction motor there are a number of benefits for the user. Slipring motor and LRS compared to squirrel cage and VSD Starting current and torque Ac Squirrel cage motors draw around 500% to 900% of Full Load
use of big mill grinding circuits, where large power gearless motor drives with cycloconverters in the range around 20 MW are being applied for semiautogenous (SAG) mills and recently, ball mills are also being considered. This work addresses some current issues involving design and application of highpower drives employed in SAG grind
WhatsApp)