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Are motor conductors sized to the locked rotor current?
According to 2011 nfpa 70 nec Motor conductors are sized with the flc- full load current or the nameplate rating fla- full load amperes
Describe the steps you take to troubleshoot a 3 phase 480 volt motor that continually trips the heaters?
Start by checking the motor current when the motor is running under load with a clamp on amp meter. If it is over nameplate rating, check and find out if the load the motor is driving is somehow dragging and creating more load that normal. 98% of the time it is the load seizing up that causes motors to trip. Drop the load off the motor and see if the motor runs under nameplate amperage. If it does that is good. Check for loose connection in the motor contactor and around the overload heater block. Check and make sure the overload heaters are set to the FLA of the motor. As a last resort megger the motor to make sure one of the phases has not grounded out.
What size breaker is needed for a 125 hp motor?
It depends on what the amperage of the motor is. The motors amperage depends on the voltage of the motor. The higher the voltage the motor operates on the lower the amperage. So unless the amperage from the motor's nameplate is stated an answer can not be given.Just remember that the feeder capacity to the motor has to be 125% of the motors full load amperage and the breaker protecting the conductors to the motor has to be rated at 250% of the motors FLA. This higher breaker size allows the motor to start without tripping a normal size breaker that is rated for the lower conductor size.
How do you determine a 3 phase motor and each winding?
To see if the motor is three phase or single phase look at the motor's nameplate. There it will tell you what the voltage needs to be and what system phase the motor needs to be connected to operate properly.
What is the ratio between locked rotor current and full load current?
Each motor has a published manufacturer Lock Rotor Amperage (LRA) rating that is used to obtain this ratio. If a manufacturer otained a reading of 100A while bench testing their motor (equipment) at full load, if the motor FLA (Full Load Anps) is 50 amps, the raito LRA to FLA is 2 to 1 or 200%.
What is the FLA at 230 volts with nameplate amps of 20 and voltage of 230?
If the nameplate states 20 amps then that is the full load amperage when the motor is running. The start up current on the motor could reach 300% of the FLA depending on the type of motor and the load that is connected to the motor.
How can you find motor FLA without the motor nameplate The motor is single phase 120 vac?
See related links below.
A particular 3 phase induction motor has a LRA of 100 amps What is its approximate starting current?
LRA (locked rotor amperage) is not considered. Starting current for a motor is usually in the neighbourhood of 300% of the FLA (full load amps). The FLA is taken from the motor's nameplate.
What is Ratio between starting and running current of 3 phase ac motor?
The start up current should be listed on the motor nameplate as FLA , full load amps.
Are fuse sized for three phase motor two times the nameplate rating?
Not normally. They are sized slightly above the LRA ( locked rotor amps) or the FLA (full load amps) stated on the motor nameplate. The startup current of a motor can be 125-150% of the running load amperage. This depends on the motor, its EFF (efficiency) and the torque requirement of the load.
Are motor conductors sized to the locked rotor current?
According to 2011 nfpa 70 nec Motor conductors are sized with the flc- full load current or the nameplate rating fla- full load amperes
What is Full Load Amps?
FLA is the nameplate amperage rating of the motor when it is running at its designed horsepower and on the motors designed voltage. 746 watts = 1 HP. The FLA of a 1 HP motor at 240 volts would be W = amps x volts, Amps = Watts/Voltage. 746/240 = 3.1 amps full load. Overload the motor and the amps go higher, motor running at no load amps are lower than FLA
How do you select the over load relay setting of a motor control starters?
First go to the motor and look for the FLA (Full Load Amps) rating on the motor nameplate. If the over load block is of the old style that uses bolt in heaters, look on the inside cover of the magnetic contactor cover. There is a list of proper manufacture heater numbers that will correspond to the FLA. If the overload block is of a newer design then all you do is turn the screwdriver slot dial to the number that matches the motor FLA.
How do you find the nameplate motor when the nameplate motor is lost?
you can call the manufacture who made the equipment with a model number and serial number of that particular piece of equipment. for example in blower assembly or ac unit
What is meant when the nameplate reads DC motor?
It means that the voltage that supplies the motor has to be a direct current source.
What is Fla motor?
Fla motor refers to a type of electric motor commonly used in various applications, including robotics and automation. Fla motors are known for their efficiency and reliability, often integrating advanced technologies for precise control and performance. They can vary in design and specifications, catering to different industrial needs.
Describe the steps you take to troubleshoot a 3 phase 480 volt motor that continually trips the heaters?
Start by checking the motor current when the motor is running under load with a clamp on amp meter. If it is over nameplate rating, check and find out if the load the motor is driving is somehow dragging and creating more load that normal. 98% of the time it is the load seizing up that causes motors to trip. Drop the load off the motor and see if the motor runs under nameplate amperage. If it does that is good. Check for loose connection in the motor contactor and around the overload heater block. Check and make sure the overload heaters are set to the FLA of the motor. As a last resort megger the motor to make sure one of the phases has not grounded out.
