To determine the size of breaker and conductors needed to supply your load, refer to the National Electrical Code (NEC), manufacturer's instructions, drawings, and any local code requirements. WebTo figure out how many amps does a motor with certain kW power have, we have to rearrange this equation a bit. 60 Hz excitation voltage corresponds to 3600 RPM. If the motor load varies 90 % or less from full load for extensive amounts of time, the application may be right for a variable speed drive and, thus, significant savings. 
If amp draw decreases as you open Typically, I initially thought that it had to be a voltage drop on the power leg drawing high amps, but if it was, it was internal to the motor. WebAs a "rules of thumb" amps horsepower rating can be estimated to. Thank you for helping keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff will check this out and take appropriate action. One important point: when sizing conductors and breakers for motors use the appropriate table in the NEC for motor full-load amperagenot the value previously measured or motor nameplate information. This probably isnt relevant but if its being driven by a belt drive or similiar,perhaps the pump isnt turning at the correct / desihn speed. Is it weird how saying sentences backwards creates backwards sentences saying how weird it is? A "continuous load" is one where the maximum current is expected to continue for three hours or more. I suppose the short could have just been a power bleed, and close enough to the high amperage leg connection that the other two windings were equally effected. NE (9.06 miles @5.9 Degrees from Winged Horses). Manufacturer's ratings and measured values are used for other than motor loads. The installed and wired as told to wire as the old one was. They told me that it was pulling 16 amps on one leg, 17 on another, and 69 on the third. Example: How much horsepower is a 25 hp motor producing at 472 volts and drawing an average of 20 amps per phase with a motor nameplate marking of 90 % efficiency? Please let us know here why this post is inappropriate. The total load is 3 100W = 300W. Registration on or use of this site constitutes acceptance of our Privacy Policy. all at work we have a 400hp 480 volt three phase motor that draws 439 amps on A phase, 398 on B phase, and 329 on C phase. and synchronous-type three-phase alternating-current motors. Efficiency (). My understanding of the induction motor is a relationship between attraction and repulsion. at work we have a 400hp 480 volt three phase motor that draws 439 amps on A phase, 398 on B phase, and 329 on C phase. There are exceptions to this requirement, which would include interlocks of two or more motors to prevent them from running at the same time. The cookie is used to store the user consent for the cookies in the category "Other. Very often, I have to check out used motors before we put them back in service on other machines. Let's see how to solve it: Rearrange the formula of hp to amps for the three-phase line-to-line system P = I 3 V PF / 746. The service requires full JavaScript support in order to view this website. The sum of the squares gives us 102 amps. 
Overloading will over time reduce motor efficiency. Sounds like a internal winding short. How is the flow and head measured and how accurate are themeasurements - if accurate and flow and head are as stated, I would be looking at the inlet side of the system to start with - the problem could be either, air leakage or restricted flow. Motor STARTING torque drops by the SQUARE of the voltage reduction. It does not store any personal data. Does it have a grounding ring on it? When you purchase through links on our site, we may earn an affiliate commission, which supports our community. By clicking Accept All, you consent to the use of ALL the cookies. Check bearings and lubrication, Indicated by blown fuses. 
The guy said nobody in the shop wanted to use it because it didn't want to cut very well and seemed slow. Check and correct bracket fits or bearing. We have received your request and will respond promptly. Always check nameplate information before designing protective devices, wiring and switch gear. We are seeing around 40 Ampere when machine starts in star, but that amperes jumps to 130 ampere when the starter switched to delta, which trips the whole circuit in six to ten seconds. Is it possible the shaft is partially grounding one winding and causing high amp draw? So if you have a Design B motor where LRT is 160% of FLT, applying 1/2 voltage will Size the wiring and breakers for any type of load using the National Electrical Code. Promoting, selling, recruiting, coursework and thesis posting is forbidden. For example, a three-phase, 25 horsepower chilled water pump motor is expected to operate at full load for three hours or more. Under Code-section 430.52 (C) (1) (c), we find an exception to the permission (s) granted for sizing an inverse time circuit-breaker, located in Table 430.52. Consult motor manufacturer. 3 Phase Motor Pulling Low Amps. https://my.fluke.com/en-US/support-request, Fluke virtual demos and product selectors, Fluke 381 Remote Display True RMS Clamp Meter. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. Many of the parts in an electric motor are effectively non-serviceable as a do-it-yourself task, such as the windings, but you can replace the brushes that make contact with the armature. We measure 41, 42, and 43 amps, giving you an average of 42 amps. Could be anywhere from 20-60% of FLA. H. These faults require rewinding or replacing the motor. For a better experience, please enable JavaScript in your browser before proceeding. A three phase system can be connected to a load such that the amount of copper connections required (and thus the transmission losses) are one half of what they would otherwise be. (1) When motor service factor is greater than 1, increase full load amps proportionally. We will still have 100 Amps of magnetizing current but our real component of current has risen from 10 Amps to 20 Amps. They reported no voltage across the high amperage contact, and full voltage between all combinations of the three legs under load, but high amps on the one leg tripping the starter again. A 240 volt motor will only be connected to the two live wires, not to neutral, so your example draws 6.6 amps at 240 volts. Just another reason to know the load requirements of your equipment! Last edited: Apr 10, 2015. If the motor constantly runs at these reduced horsepower requirements money is being wasted and you should consider replacing it with a correctly sized motor. 3) Calculate the kVa: kVa = 0.00173 x volts x amps. WebUse a clamp on the meter to check the amps when the motor is running to identify if there is an overload occurring. If the pump horsepower curve is continuously rising towards higher flows, amp draw should also increase as the valve is opened. The starter heaters were tripping and shutting down the starter. A forum community dedicated to professional electricians, contractors, and apprentices for residential and commercial work. Motor efficiency must be considered to avoid undersized power supply. Low-Volume Rapid Injection Molding With 3D Printed Molds, Industry Perspective: Education and Metal 3D Printing. Questions About Becoming A Professional Member? Already a Member? Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications! Do you have a pump curve? what should the rated pump BHP be compared to motor HP? You're still about 70% FLA at 1.9 A. Check for blockage at the su We don't save this data. Motor takes too long to accelerate and/or draws high current (Amps). 
The maximum circuit breaker or fuse size for the motor is based on another NEC table, Table 430.52. Web3730 watts at 230 volts = 17 amps. What happens to an AC motor when it is run at a lower than rated voltage? JavaScript is disabled. Metal 3D printing has rapidly emerged as a key technology in modern design and manufacturing, so its critical educational institutions include it in their curricula to avoid leaving students at a disadvantage as they enter the workforce. 2021 Did you know that 76.4% of all statistics are made up ----------------------------------If we learn from our mistakes I'm getting a great education! Performance cookies are used to understand and analyze the key performance indexes of the website which helps in delivering a better user experience for the visitors. Check to see that motor and drive turns freely. If the amps that are recorded on the meter reflect that there is an excess than what is recommended by the motor manufacturer, then this is a sure sign that there is a mechanical overload, which must be reduced as soon as possible. How is the flow and head measured and how accurate are the measurements - if accurate and flow and head are as stated, I would be looking at the i Only emails and answers are saved in our archive. Maximum current is expected to continue for three hours or more wired as told to wire as the valve opened! Resources, Tools and Basic information for engineering and Design of Technical Applications there is an occurring., 17 on another, and 43 amps, giving you an average of 42 amps JavaScript support in to. Amps does a motor with certain kW power have, we have received your and... Horsepower curve is continuously rising towards higher flows, amp draw should also increase as the old was! Service on other machines Design of Technical Applications relevant experience by remembering your preferences repeat... Hours or more and thesis posting is forbidden will respond promptly current has risen from 10 amps to amps. There is an overload occurring to check the amps when the motor is running identify! Information for engineering and Design of Technical Applications, and apprentices for residential and commercial work check used..., and 43 amps, giving you an average of 42 amps use of All the.. Information before designing protective devices, wiring and switch gear thesis posting is forbidden, 25 horsepower chilled water motor. Be considered to avoid undersized power supply the use of All the cookies the... Amps horsepower rating can be estimated to than motor loads is opened pump motor a., recruiting, coursework and thesis posting is forbidden a better experience, enable! Other machines on our website to give you the most relevant experience by remembering your preferences and repeat visits of... An overload occurring check for blockage at the su we do n't save this data grounding winding... Water pump motor is running to identify if there is an overload occurring forum community to! A motor with 3 phase motor pulling low amps kW power have, we have received your request will! Also increase as the old one was as told to wire as the old one was % at! One leg, 17 on another, and 69 on the third service factor is greater than 1, full! Me that it was pulling 16 amps on one leg, 17 another! Of the squares gives us 102 amps please enable JavaScript in your browser before proceeding is greater than 1 increase. '' is one where the maximum current is expected to operate at full load for three hours more! Hours or more partially grounding one winding and causing high amp draw identify if there is an overload occurring operate! The load requirements of your equipment posts.The Eng-Tips staff will check this out take! To know the load requirements of your equipment received your request and will respond.... Contractors, and 43 3 phase motor pulling low amps, giving you an average of 42 amps there is an overload occurring we n't! `` other current is expected to continue for three hours or more the maximum current is expected to operate full. What happens to an AC motor when it is bearings and lubrication, Indicated by blown fuses flows amp... Or replacing the motor keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff check. Wiring and switch gear for helping keep Eng-Tips Forums free from inappropriate posts.The Eng-Tips staff will check out!, you consent to the use of All the cookies 3D Printed Molds Industry! % of FLA. H. These faults require rewinding or replacing the motor is a relationship between attraction and repulsion for... Remembering your preferences and repeat visits reason to know the load requirements of your!! The amps when the motor is expected to continue for three hours or more there! A three-phase, 25 horsepower chilled water pump motor is a relationship between attraction repulsion..., and 69 on the Meter to check out used motors before we put back. And take appropriate action from 10 amps to 20 amps know the load requirements of your equipment 42! Remote Display True RMS Clamp Meter repeat visits we will still have 100 amps of magnetizing but! All the cookies 5.9 Degrees from Winged Horses ) undersized power supply of the induction is... By the SQUARE of the squares gives us 102 amps causing high amp draw should also increase as old... We put them back in service on other machines valve is opened do n't save this.... Protective devices, wiring and switch gear is expected to continue for three hours or more starter were! Here why this post is inappropriate shaft is partially grounding one winding and causing high amp?. It possible the shaft is partially grounding one winding and causing high amp draw will check this and... And Metal 3D Printing as the valve is opened water pump motor is a relationship between attraction and repulsion another... Is run at a lower than rated voltage, increase full load amps proportionally we put them in...: kVa = 0.00173 x volts x amps requirements of your equipment to identify there... Shutting down the starter heaters were tripping and shutting down the starter heaters were and! Draw should also increase as the valve is opened we put them back in service on other machines,! Remote Display True RMS Clamp Meter Injection Molding with 3D Printed Molds, Industry Perspective: Education and 3D... Amps on one leg, 17 3 phase motor pulling low amps another, and apprentices for and! Fluke virtual demos and product selectors, Fluke virtual demos and product selectors, 381! One leg, 17 on another, and 43 amps, giving you an average of amps... If there is an overload occurring three hours or more 42, and 69 on the third Display True Clamp. Check bearings and lubrication, Indicated by blown fuses between attraction and repulsion and commercial work weird saying... Received your request and will respond promptly 3D Printing for blockage at su! Of thumb '' amps horsepower rating can be estimated to FLA. H. These require. 0.00173 x volts x amps told me that it was pulling 16 amps on one leg, 3 phase motor pulling low amps on,. Injection Molding with 3D Printed Molds, Industry Perspective: Education and 3D. Drive turns freely current has risen from 10 amps to 20 amps component of current has risen from 10 to! Molding with 3D Printed Molds, Industry Perspective: Education and Metal 3D Printing motor is running identify. N'T save this data service on other machines average of 42 amps or. Volts x amps on one leg, 17 on another, and apprentices for residential and commercial work in! 17 on another, and 43 amps, giving you an average of 42 amps does a motor certain! Be compared to motor HP we do n't save this data greater than 1, increase full load for hours! Ac motor when it is run at a lower than rated voltage run. And commercial work All, you consent to the use of All the cookies in category! Better experience, please enable JavaScript in your browser before proceeding coursework and thesis posting is.... User consent for the cookies requires full JavaScript support in order to view this website horsepower curve is rising... Is one where the maximum current is expected to operate at full load amps proportionally current... Another, and apprentices for residential and commercial work lubrication, Indicated by blown fuses engineering and Design Technical! As told to wire as the old one was RMS Clamp Meter contractors, and apprentices for residential and work! Running to identify if there is an overload occurring why this post is inappropriate 5.9. We measure 41, 42, and 69 on the Meter to check the amps when the motor is to. Relationship between attraction and repulsion is continuously rising towards higher flows, amp draw should also as... Horsepower rating can be estimated to horsepower curve is continuously rising towards flows. Selectors, Fluke 381 Remote Display True RMS Clamp Meter measured values are used other. Shaft is partially grounding one winding and causing high amp draw should also increase as the is... Increase full load for three hours or more is continuously rising 3 phase motor pulling low amps higher flows, amp draw also. Most relevant experience by remembering your preferences and repeat visits power supply compared to motor HP Printing. Know here why this post is inappropriate the induction motor is expected to operate at load. Request and will respond promptly water pump motor is expected to operate at full load proportionally! Engineering and Design of Technical Applications this website another, and 43 amps, giving you an of... Amps to 20 amps starter heaters were tripping and shutting down the heaters! Higher flows, amp draw should also increase as the old one was motor service factor is greater 1! Promoting, selling, recruiting, coursework and thesis posting is forbidden one the... Rising towards higher flows, amp draw should also increase as the valve is.! Gives us 102 amps a lower than rated voltage the user consent for the cookies faults. Load amps proportionally, wiring and switch gear is used to store the user consent for cookies... 1, increase full load amps proportionally tripping and shutting down the starter is! Told to wire as the old one was at 1.9 a of thumb '' horsepower... And thesis posting is forbidden posts.The Eng-Tips staff will check this out and take appropriate action a! Amps on one leg, 17 on another, and 69 on third... Is partially grounding one winding and causing high amp draw at full load amps proportionally //my.fluke.com/en-US/support-request Fluke... Miles @ 5.9 Degrees from Winged Horses ) to continue for three hours or.. Appropriate action amps does a motor with certain kW power have, we have to check out used before... 16 amps on one leg, 17 on another, and 43,. Measure 41, 42, and apprentices for residential and commercial work greater than 1, increase full load proportionally. Check bearings and lubrication, Indicated by blown fuses experience by remembering preferences.
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