causes of high current on sag mill motors

Voltage sag - Wikipedia

BALL MILL DRIVE MOTOR CHOICES charge will set the magnitude and time of the inrush current during mill starting The inertia for this mill B SYNCHRONOUS MOTOR WITH AIR CLUTCH The high starting torque design synchronous motors directly connected to the mills have been used for years This type of drive would be able to accelerate the

Overheating Electric Motors A Major Cause of Failure

This causes the flow of current to rise dramatically creating overcurrent Miswiring Miswiring can cause overcurrent in motors If the wiring is incorrect on a motor it can lead to shorts and other problems Shorts can cause fires and if left unattended will ruin the motor This can be avoided by checking the schematics of engines to ensure

Mill grinding - Wikipedia

Feb 23 2018· High no-load current Motor not rewound One situation in which higher-than-expected no-load current can occur is with reconditioned motors Although some motors with no-load currents above or below the guidelines shown in Table 1 may still be satisfactory motors with no-load current outside of these ranges warrant further analysis

What are possible causes of motors drawing high current

Flickering Lights Intermittent Electrical Power Loss Diagnose fix flickering or dimming lights or lost electricity How to diagnose the causes of flickering or dimming lights at or in buildings This article gives simple diagnostic steps that a homeowner can do to determine the type of electrical system problem that is causing flickering or dimming lights or intermittent loss of electrical

What is the reason causes motor tripped

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 …

3 - PAPER - Michael Hamilton - FINAL

mill angle for a Frozen Charge trip at a large SAG mill for reference The speed is following the preset speed ramp until the trip shuts of the motor and lets the mill oscillate The torque value is constantly growing and the mill angle indicates turning until 85° for Frozen Charge verification followed by the trip

Sag Mill Synchronous Motors - Henan Mining Machinery and

Mar 11 2007· What would be a probable cause of a high current draw during starting Answer Save 3 Answers Relevance Anonymous 1 decade ago Favorite Answer The starter motor naturally draws a high current If its an unusually high current but the vehicle still starts then you may want to check the battery cables They could be corroded inside the

Causes of Voltage Sag GoHz com

developed for single pinion or dual pinion applications depending on the power of the driven mill High speed solution Typically a high speed squirrel cage motor with three or four pole pairs is used for this kind of configuration A gearbox is needed in this solution where the high speed side is connected to the motor

Current Issues on High-Power Cycloconverter - fed Gearless

Motor starting is an important issue which must be considered when applying a generator set The high current that motors draw when starting causes voltage dips in the system This may require oversizing the generator or applying motor starting techniques maintain this voltage dip at acceptable levels for your system and its attached components

SAG Mill Grinding Circuit Design

Motor starting causes high inrush currents and the absence of a good understanding of the inrush current which causes the power quality events may spoil the motor or affect the sensitive load at its surrounding which causes post-fault voltage sag sometimes lasting for a

ABB s new Gearless Mill Drive generation Maintenance

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 …

SAG Mill Motor Breakdown - PanAust

SAG is an acronym for semi-autogenous grinding SAG mills are autogenous mills that also use grinding balls like a ball mill A SAG mill is usually a primary or first stage grinder SAG mills use a ball charge of 8 to 21 The largest SAG mill is 42 12 8m in diameter powered by a 28 MW 38 000 HP motor

AG SAG Mill Grinding Circuit Automatic Control

8-3 Centrifugal force outward Fc mp 2 Dm 2 8 1 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 8 2 The particle will remain against the wall if these two forces are in balance ie

Locked charge protection algorithms robust to coordination

The 10 and -15 voltage tolerance in most manuals is the recommended operating range to allow the drive to maintain premium efficiency and proper motor current Drives can run below these tolerances but reduced voltages can have unpredictable effects on motor current temperature energy use and overall performance

Voltage Sags Dips and Swells - Power Standards Lab

Apr 02 2008· In general my first guess would be that the load on each motor is different and that things are fine Especially if the phase currents and voltages are balanced on multiphase Check to see if the temperature of the motors differs significantly If greater than nameplate temperature rating them something may be wrong

SAG Mill Motor Breakdown - PanAust

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

Sources of Voltage Sags - Power Standards Lab

Sag Mill Synchronous Motors Prompt Caesar is a famous mining equipment manufacturer well-known both at home and abroad major in producing stone crushing equipment mineral separation equipment limestone grinding equipment etc


Another cause assuming reduced voltage start star delta autotransformer primary resistance soft start etc could be that the motor is not delivering torque sufficient to accelerate the connected load to speed That is the starting current and starting time under RVS …

Milling - Energy intensive and high maintenance

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

Uneven SAG Mill Drive Power Draw - Grinding

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 re-cently ball mills are also being considered This work addresses some current issues involving design and application of high-power drives employed in SAG grind-

What Causes Overcurrent in an AC Motor Hunker

ABB s new Gearless Mill Drive generation Maintenance-friendly features raise availability and productivity Axel Fuerst Reinhold A Errath Sebastian Gaulocher SAG Mill Figure 2 Core to gather information on the causes The precise conditions for the high temperature were detected

Flickering Lights Electrical Power Loss Diagnose Repair

As a result while both phenomena can be disruptive in a system and cause considerable damage generally speaking voltage surges are considered more damaging This is due to the longer period of time in which the electric circuit must deal with the excessive power What Causes Voltage Surges Engineers generally recognize two causes of voltage

Control Engineering Preventing VFD faults and failures

Abstract A locked charge drop incident in a ball or sag mill is a catastrophic failure that causes high repair costs and loss of production The locked charge event also produces high currents and torque demands which can cause the drive or transformer overcurrent relays trip the mill motor

Voltage Surges Causes and Control - Sollatek

For the high tonnage tests feed rates should be increased to meet or exceed the normally acceptable load on the SAG mill motor or load in the mill whichever has been identified as the primary constraint An example of the relationship between mill motor current power draw and SAG mill feed rate is given in Figure 2

What would be a probable cause of a high current draw

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


The motor might be a pump a compressor a fan part of an HVAC system Most voltage sags originate within your facility The three most common causes of facility-sourced voltage sags are Starting a large load such as a motor or resistive heater Electric motors typically draw 150 to 500 of their operating current as they come up to speed

Coupling Alignment Fundamentals - Rexnord

high power factor of about 0 95 over the complete speed range generation of low harmonic currents which cause only low harmonic voltages in the power supply network normally no need for filter circuits Disadvantages of the voltage source converters compared to cyclo-converters are current derating at motor frequencies smaller than

Comparison between Dire ct-On-Line Star-Delta and Auto

However this motor initial current surge is long so in most cases a unrealistically large capacitor would be needed to make a significant difference A small capacitor across a motor can help to reduce emissions The capacitor keeps the voltage more steady and keeps the high frequency noise current circulating close to the motor

Resolving Voltage Problems with AC Induction Motors

Coupling Alignment Fundamentals Rexnord 5555 S Moorland Rd New Berlin WI 53151-7953 538-214 Telephone 262-796-4060 Fax 262-796-4064 February 2014 August 2013 Page 1 of 14 CONTENTS I Why Align Rotating Equipment II Defining Shaft Misalignment III Alignment Methods — Poor Fair Good and Best IV