motor loaded circuits
motor loaded circuits
(OP)
Everytime i look up some fault calculation a low voltage system having a motor loaded circuits, it appears the fault current contribution of SMALL MOTOR and LARGE MOTOR were approximated to a value of 20% to 25% reactance, respectively. Why and how this value obtained?
As i refer to IEEE 115-19xx, "guide and test procedure for synchronous machine transient parameters" a table of typical machine reactance and time constants were tabulated.. i found out that 20%-25% reactance falls right under the motor with specific rpm.. Does this tabulated typical reactance were used as the basis for small and large motor? How this value affected by RPM, HP/KW, ROTOR CONSTRUCTION, etc?
all comments are welcome!
thank you..






RE: motor loaded circuits
I think it is just a fact of life for all motors
RE: motor loaded circuits
For small motors, the subtransient reactance is almost never known, so some approximation is required. You also have to take into account the impedance of the cable feeding the motor. This adds considerable resistance for small motors.