What is my problem? Do I have a load that is too large on the motor.Here are the specs:AC 3-PhaseContinuous DutyConstant ToquePower Output: 5 HPBase_RPM: 1750Service Factor: 1.15Power Factor: .75Namplate Current: 14.2 AmpsNameplate Voltage: 230 VWhat I'm doing is increasing the speed of the motor with a VFD. The motor will turn the rotor up to 300 RPM (Well below its base RPM) before it exceeds its nameplate current, which causes the motor to be tripped. Is the motor drawing current above it's rated value to produce more torque to spin the flywheel? The motor can produce 15 ft*lb of constant torque at any speed up to its base rpm, and it is drawing 15.5 Amps at 50 Volts before it trips.
The motor full load current rating is only 14.2 amperes and is drawing 15.5 amperes before it trips. It means, the thermal overload relay is starting to heat up at this stage.Either, you reduce the load or the speed so that the rated current won't be exceeded.
The start up torque and current is much higher than normal torque, it is surely a case of trip due to exceeding start up current. you are putting much more torque on the motor at the start up . If you are using VFD , i don't know the mode of control of VFD , you need to have stringent criteria of VFD control so that the rate of increase of load on rotor is controlled . Try to have a control in the secondary mover system parameters by inducing throttles or check the setting of VFD ! i remember a pump used to get tripped when the pipe downstream of pump was hollow instead of fluid, the pump used to start and go in run out and subsequenctly trip due to overload trip ! i installed a control valve downstream to close it , fill the line and increase the system resistence and the system started functioning well as torque on motor was reduced during start up !
I assume that when you say that the motor is tripped, you are referring to the electronic overcurrent trip function of the VFD. You can probably increase the trip point to 150% of rated output current unless the VFD is rated only for use with centrifugal pump and fan loads. In that case, it is not expected to be capable of providing rated motor torque below full speed. You need to read and understand the VFD manual. There may be several adjustments and/or a tuning procedure that needs to be performed. It is also possible that the VFD is defective, the motor is defective, or there is a fault in the wiring between the VFD and motor. What is the brand and model of the VFD?
