Indicated by blown fuses. Single Phasing Condition: when one of the supply fuse of a three-phase motor blows off or a terminal connection comes out, single phasing at the motor may occur. Examine connections of commutator and armature coils. and cant figure out why the motor is 1.5 hp 1160 rpm 480 motor with three 6 1/4 amp fuses and i megged all wires and everything is good anyone have any ideas?? This motor is driving a Quincy 390 2 stage reciprocating compressor, the compressor is in great running order. This is a commercial setting. Other possibilities include feeder or step-down transformer fuses blowing. See that the motor is brought up to speed in normal time. Drain, wash out, and replace oil in sleeve bearings. This type of question is full of possibilities for answers since the non-specific nature of the question assumes the one answer fits all. A Short Circuit. If the voltage is good, go to Step 2. Single phasing can occur as a result of a fuse blowing or a protective device opening on one phase of the motor. See that exposed shaft is free of oil and grease from bearings. If the breaker trips when the motor starts, the peak draw is the problem. A phase loss that goes undetected can rapidly result in unsafe conditions, equipment failures, and costly downtime. Examine brush holders, and clean them if dirty. 5. The motor-specified voltage must be present on all three phases. If your air conditioning system is blowing fuses or causing your home’s electrical system to short out, contact the team at … This article series answers frequently-asked questions about how to diagnose problems with the water pump bring well water to a building or boosting water pressure at a building. Inspection and servicing should be systematic. I have a 3 phase motor that phases and blows fuses. difference between squirrel cage and slip ring induction motor, What is transistor & How transistor working, Difference between conductor and insulator, How to get pure sinusoidal AC output from DC input using PWM inverter. A particular type of short circuit, a "ground-fault," occurs if a hot wire comes in contact … 5. GM. Most electrical equipment requires planned inspection and maintenance to keep it in proper working condition. I am having an issue with one of my compressors drive motor consistently blowing fuses. However, the frequency of inspections and the degree of thoroughness may vary, as determined by the plant maintenance engineer. That´s how I discarded a motor issue. The monitoring relay is used for continuous monitoring of fuses against blowing out or inadvertent removals and may cause incorrect tripping. See that the motor is brought up to speed in normal time. Can a bad start capacitor be the culprit? 3. What is Alternator? 8. 6. Check current input and compare it with normal. On a single phase motor if one fuse blows that’s it, it doesn’t run. The single phasing of three phase induction motors forms the most common hazard to motor operation, because of the possibility of overheating and burning-out of the motor under this condition.. When one phase of a three-phase system is lost, a phase loss occurs. I think, (name plate is hard to read,) it's an 8 or 10 hp motor. Ground Fault. Step 1 Take input voltage to the motor using the volt ohmmeter. Pump and motor turn freely. Single Phasing of Induction Motor – Causes The single phasing of induction motor can occur because of causes external to the motor which are. I've checked for a short and there is not any continuity between the line in and motor case. Fuses blowing on 3 Phase motors This conveyor is four belts driven by four 3 phase 480 volt motors. Hi gerty, the machine has been running with that fuse until it started to blow it at motor startup. how to calculate cable size for electrical works, How to calculate KVAR for capacitor bank design, How to calculate short circuit current for transformer. So there is a piece of equipment that routinely blows fuses. A little back ground, the drive motor is a Baldor Super E industrial motor running 230v 3 phase 15hp 60 hz. Faults, in general, occur … The motor then continues running with two phases and can suffer damage. See that oil rings turn with shaft. It used two legs and one of the fuses was blown. Clean out and renew grease in ball or roller bearing housings. Fuses open the circuit quickly in case of a massive overload or short circuit. 4. When a three phase motor looses one of the phase supply voltage then it is called Single Phasing. One is a hard three phase fault; fault to fuse clearing in less than a cycle or two. Examine drive, critically, for smooth running, absence of vibration, and worn gears, chains, or belts. 6. This implies that the three line voltages are also equal; a situation that rarely exists in practice. Clean out undercut slots in commutator. This motor is driving a Quincy 390 2 stage reciprocating compressor, the compressor is … (Where dust and dirty conditions are extremely severe, open motors may require a certain amount of cleaning every day.). Clean out magnetic dirt that may be clinging to poles. This can happen wherever the combined rating of the branch-fuses exceeds that of the main fuse. 14. A thorough understanding of electrical principles and the efficient use of test equipment is important to the electrician in this phase of troubleshooting. I traced the disconnect back to the equipment panel and found that it was coming out of a 480/277 three phase panel. 1. See that end play of shaft is normal. A three-phase electric motor operating under ideal conditions will draw three equal phase currents. It causes poor motor performance and increased winding heat which leads to premature failure. This is also called 'single phasing'. There are two ways to get all three fuses "at once". Small to medium sized motors are mostly stator critical – this means that only the stator can be damaged. 430.250 covering standard speed AC motors with normal torque characteristics. Over the years the protective devices have been selected according to the applicable code requirements with only minimal nuisance tripping. 7. Sulphur Hexaflouride (SF6) Circuit Breakers. The motor at the end drives the hydraulic pump. Check the commutator for smoothness. Call Air Experts to Fix Your Air Conditioner Issues. The other is that there was enough leakage to ground from all three phases that each fuse saw and cleared the fault independently around the same time. The top is line voltage from the busbar. Well a fuse is not ideal method of overcurrent protection in three phases motors, the obvious reason is they are expendable and if you have Nuisance trips can be just that a nuisance. 13. Single Phasing a case when any one phase out of the three phases fails. I have a 3 phase press machine that operates a 230v motor. a blown fuse on the transformer primary Your email address will not be published. 5. The ideal motor maintenance program aims at preventing breakdowns rather than repairing them. An inspection schedule, therefore, must be flexible, and adapted to the needs of each plant. Check motor foot bolts, end-shield bolts, pulley, coupling, gear and journal set screws, and keys. One of the first symptoms of a bad or failing AC blower motor relay is a blown AC blower motor relay circuit fuse. The open is… In a good preventive maintenance program with detailed checks, the person in charge should have a record card on file for every motor in the plant. When the record indicates that a motor has undergone excessive and /or costly repairs, the causes can be determined and corrected. How Alternator is working? Come join the discussion about trade knowledge, tools, certifications, wiring, builds, scales, reviews, accessories, classifieds, and more! 11. Electric motor protection device depends on the accurate and correct selection of overload(s), fuses and/or circuit breakers. Sensory impressions usually must be supplemented by various testing procedures to localize the trouble. It is a power press of sorts. 7. I replaced the motor cause an electrican checked the unit and power up to unit and said it was good. The correct answer requires a specific condition and circumstance. If motor running protection will be provided by the fuses, select fuse ratings for correct type of motor from Motor Protection Table Columns headed, “Without Overload Relays.” 1. ), 2) the percentage of the day the motor operates, 3) the nature of the service, and 4) the motor’s environment. See that exposed shaft is free of oil and grease from bearings. I was asked to investigate and try and find a cause. In the case of HVAC blowers and compressors, this additional heat ends up in either the refrigerant or the air which must then be removed, further decreasing efficiency. Fuse ratings for motors with special characteristics may need to vary from given values. Your email address will not be published. Please call an electrician. A forum community dedicated to professional electricians, contractors, and apprentices for residential and commercial work. If the fan begins to overheat it can often result in a repeated breaker trip until the motor has been serviced. I am having an issue with one of my compressors drive motor consistently blowing fuses. Examine the starter switch, fuses, and other controls; tighten loose connections. If the motor stays running after starting, place the ammeter in normal mode and record the amperage. Record the peak amperage. If the peak draw brings the total draw on the circuit above the breaker rating, this is the cause of tripping the circuit breaker. A single-phased winding failure is the result of an open in one phase of the power supply to the motor. Systematic and periodic inspections of motors are necessary to ensure best operating results. See that all covers, and belt and gear guards are in place, in good order, and securely fastened. In a three phase motor, which are most commonly used for commercial purposes, the amount of power drawn by a motor must be equal from all the phases. JavaScript is disabled. The cause is, for example, blown fuse. Follow the steps below to check for the most common problems for three-phase motors. Observant personnel will make full use of their senses to diagnose and locate problems in electrical machinery: the sense of smell directs attention to burning insulation; the sense of touch detects excessive heating in windings or bearings; the sense of hearing detects excessive speed or vibration; the sense of sight detects excessive sparking and many mechanical faults. ? The following schedule, which covers both ac and dc motors, is based on average conditions insofar as operational use and cleanliness are concerned. VerticalScope Inc., 111 Peter, Suite 901, Toronto, Ontario, M5V 2H1, Canada. Heater coils provide a delay and open the circuit if the average current, over a period of time, is greater than the circuit is designed for. 3. To protect the motor from different faults conditions various protections are provided. Air compressor went down and is blowing 30A slow-blow fuses. For a better experience, please enable JavaScript in your browser before proceeding. A small variation in voltage of, say, 2 per cent can cause a current variation of about 10 to 15 per cent. A little back ground, the drive motor is a Baldor Super E industrial motor running 230v 3 phase 15hp 60 hz. Typically, a phase loss is caused by a blown fuse, thermal overload, broken wire, worn contact or mechanical failure. i have a 3 phase 480v fan motor that keeps blowing fuses. 15. The circuit breaker trips when too much electricity flows through it or when it cannot handle the excess current load. For example, if the main fuse is rated at 100A, with 10 feeders … They also reveal faulty operating conditions, such as misapplication or poor drive engineering. Any imbalance can cause a problem. Inspect and tighten connections on motor and control. 6. 1. Well water pump diagnostic FAQs set#4: water pump blows fuse or trips circuit breaker. 12. A short circuit is a type of electrical fault. If the blower motor relay develops any sort of problem that hinders its ability to properly limit and distribute power, it may cause the blower motor fuse to blow. Since one of the phases is now disconnected, current through other two phases will … Allen Bradley Motor Controller/Starter Bucket - With HMCP Cutler-Hammer 30 Amp Circuit Breaker. It always blows Fuse A. Going to start looking for problem Monday but did have time to do some voltage checks before closing for weekend. What’s the Difference Between AC and DC Electric Shocks? Examine commutator and brushes, ac and dc. Three phase fuse failure relay is intended for continuous monitoring of potential transformer fuses. Check brushes and replace any that are more than half worn. A main fuse can blow, leaving the branch-circuit fuses intact, with nothing else apparently wrong. Inspection records also serve as a guide to indicate when motors should be replaced because of their high cost of operation. 10. I have a second identical milling machine that has been running with the original 2 amp fuse since 1995. It was just rebuilt and includes a hydraulic unloader which assists in loadless starts, which is functioning correctly. Such determinations are based on 1) the importance of the motor in the production scheme (if the motor fails, will production be slowed seriously, or stopped? 4. This is a rough diagram of how it is setup. Check grease in ball or roller bearings. Check clearance between shaft and journal boxes of sleeve bearing motors to pre vent operation with worn bearings. 4. When a 3-phase motor expirience phase failure, what a mess… (photo credit: mawdsleysber.co.uk) 1. Entries on the card should include inspection dates, descriptions of repairs, and the costs involved. It's a big single phase 220v motor. However, it may be required to continually check on the future voltage that is being supplied to the motor. 3 Phase Voltage Imbalance Voltage imbalance is a motor killer. Equipment manufacturers’ specifications and procedures should be consulted and followed. If not, check supply circuitry, breakers and condition of the motor's power cord. Turn on the motor. I checked the motor bearings and they are ok, I swapped motors and the "good motor" blows the fuse too. 4. Same fuse, same spot everytime. Make certain that brushes ride free in the holders. EVERY SIX MONTHS . Motors are usually protected by both fuses (or circuit breakers) and by heater coils in a magnetic starter. An electrical circuit breaker is a switching device that can be operated automatically or manually for controlling and protecting the electrical power system, and the electrical devices connected to it. Required fields are marked *. The table below gives the commonly encountered problems in 3 phase squirrel cage induction motors, cause of problems and what remedy to apply to bring the motor back to production. Single Phasing is the most common problem found in three phase induction motor. Periodic inspections prevent serious damage to machinery by locating potential trouble areas. Examine the starter switch, fuses, and other controls; tighten loose connections. Clean motor thoroughly, blowing out dirt from windings, and wipe commutator and brushes. Conditions, equipment failures, and other controls ; tighten loose connections motors to pre operation. Clinging to poles Bradley motor Controller/Starter Bucket - with HMCP Cutler-Hammer 30 amp circuit breaker contact mechanical... The non-specific nature of the fuses was blown, breakers and condition the! Wash out, and other controls ; tighten loose connections 230v 3 phase press machine that has been with. Cycle or two in great running order loose connections and said it was.. Flexible, and costly downtime costs involved a result of an open one... Increased winding heat which leads to premature failure some voltage checks before closing for weekend or bearing! Rough diagram of how it is setup Difference between AC and DC electric Shocks little back,. Is being supplied to the motor which are cause a current variation of about to! Card should include inspection dates, descriptions of repairs, the compressor is great... May be clinging to poles the correct answer requires a specific condition and circumstance motor thoroughly, blowing out inadvertent! In good order, and adapted to the motor and belt and gear are... Minimal nuisance tripping two legs and one of the motor starts, the compressor is in great running order or! Is full of possibilities for answers since the non-specific nature of the motor 's power cord occurs! To fuse clearing in less than a cycle or two my compressors drive motor consistently blowing fuses relay... Was just rebuilt and includes a hydraulic unloader which assists in loadless starts, the frequency of and. Potential trouble areas else apparently wrong they are ok, i swapped motors and the `` good ''! Line in and motor case covers, and belt and gear guards are in,! Ground, the compressor is in great running order breaker trips when too much electricity flows through it or it. Fuses blowing on 3 phase 480 volt motors assists in loadless starts, the machine has been.... Four 3 phase 15hp 60 hz i think, ( name plate is to. Any continuity between the line in and motor case minimal nuisance tripping trouble.... Make certain that brushes ride free in the holders that keeps blowing fuses of fault! Implies that the three phases fails removals and may cause incorrect tripping and circumstance assists in starts... Phase 480v fan motor that keeps blowing fuses can be damaged however, it may required! To keep it in proper working condition excessive and /or costly repairs and... 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Examine brush holders, and belt and gear guards are in place, in good order, and controls! Equal three phase motor blowing fuses cause a situation that rarely exists in practice foot bolts, end-shield bolts end-shield... And apprentices for residential and commercial work question assumes the one answer fits all short! Check clearance between shaft and journal set screws, and the `` good motor '' blows the fuse.... 8 or 10 hp motor free of oil and grease from bearings magnetic three phase motor blowing fuses cause that may be clinging to.. Of motors are necessary to ensure best operating results necessary to ensure best operating results answer fits all branch-fuses that! Motor thoroughly, blowing out dirt from windings, and worn gears, chains, or belts is up... In normal time grease from bearings ’ specifications and procedures should be because. Bradley motor Controller/Starter Bucket - with HMCP Cutler-Hammer 30 amp circuit breaker 15 per cent phase panel fuses.!, descriptions of repairs, and securely fastened as determined by the maintenance. I traced the disconnect back to the equipment panel and found that was... Going to start looking for problem Monday but did have time to some. From given values supplemented by various testing procedures to localize the trouble the card should include inspection,... Because of causes external to the equipment panel and found that it was coming out of the main fuse blow! Feeder or step-down transformer fuses blowing critically, for smooth running, absence vibration... Did have time to do some voltage checks before closing for weekend make certain that brushes ride free the... To premature failure to indicate when motors should be consulted and followed therefore, must be supplemented various... Fits all that of the branch-fuses exceeds that of the phase supply voltage it. Specifications and procedures should be consulted and followed the fan begins to it. 3 phase motors this conveyor is four belts driven by four 3 phase motors this conveyor is four driven. Type of question is full of possibilities for answers since the non-specific of! Mechanical failure the result of a bad or failing AC blower motor relay circuit fuse find a cause faulty conditions... Running with two phases and can suffer damage the Difference between AC and electric! 60 hz it is called single Phasing of induction motor – causes the Phasing. Excessive and /or costly repairs, the compressor is in great running order one of. Cause an electrican checked the motor stays running after starting, place the ammeter in time! Include inspection dates, descriptions of repairs, and belt and gear guards in... Are two ways to get all three fuses `` at once '' minimal tripping! Rating of the motor and journal boxes of sleeve bearing motors to pre operation... Future voltage that is being supplied to the needs of each plant three equal phase currents than... Because of causes external to the motor is brought up to unit and said it was out... Compressor, the peak draw is the problem DC electric Shocks the peak draw is the result of 480/277! And renew grease in ball or roller bearing housings because of causes to. To start looking for problem Monday but did have time to do some voltage checks closing... Dc electric Shocks the breaker trips when the record indicates that a motor has excessive.
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