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Rating plate of three phase induction motor includes
Output power
Speed
Frequency
All of above
All of above
The rating plate (or nameplate) of a three-phase induction motor provides vital technical specifications required for its safe installation, operation, and protection. According to IS 325 / IEC 60034 standards, it must explicitly state the rated output power (in kW or HP), full-load speed (in RPM), and supply frequency (in Hz). Consequently, all the listed parameters are included on the rating plate.
The rating plate (or nameplate) of a three-phase induction motor provides vital technical specifications required for its safe installation, operation, and protection. According to IS 325 / IEC 60034 standards, it must explicitly state the rated output power (in kW or HP), full-load speed (in RPM), and supply frequency (in Hz). Consequently, all the listed parameters are included on the rating plate.
PoutтАЛ=3тАЛ├ЧVLтАЛ├ЧILтАЛ├Чcos╧Х├Ч╬╖ тАФ Mechanical output power delivered at the shaft
NsтАЛ=P120├ЧfтАЛ тАФ Synchronous speed equation relating frequency (f) and poles (P)
s=NsтАЛNsтАЛтИТNrтАЛтАЛ тАФ Slip calculation using rated rotor speed (NrтАЛ)
Output power printed on the rating plate always refers to the mechanical power available at the motor shaft, not the electrical input power.
The speed indicated on the nameplate is the actual full-load rotor speed (NrтАЛ), which is slightly less than the synchronous speed (NsтАЛ).
Frequency (e.g., 50 Hz in India, 60 Hz in US) determines the operational synchronous speed and inductive reactance of the windings.
Additional nameplate data includes rated voltage, full-load current, insulation class, duty cycle, enclosure type (IP rating), and power factor.
Ensures proper sizing and selection of protective devices like thermal overload relays and circuit breakers.
Prevents motor burnout by providing clear operating limits for voltage, current, and duty cycle.
Operation beyond nameplate ratings causes excessive temperature rise and insulation degradation.
Ratings are specified for standard ambient conditions (typically 40┬░C); operation at higher temperatures requires derating.
Determining motor compatibility with supply voltage and frequency.
Calculating full-load torque using rated output power and rated RPM.
Standard nameplates follow guidelines established by IS 325 / IEC 60034-1.
Option A (Output power) is essential to know the mechanical load capacity.
Option B (Speed) indicates the actual running speed under rated mechanical load.
Option C (Frequency) specifies the required AC supply frequency for design efficiency.
D is correct тАФ The nameplate of a three-phase induction motor includes output power, speed, frequency, along with voltage, current, and power factor ratings.
Always remember that the power rating on any motor rating plate is the shaft mechanical output power (PoutтАЛ), whereas for transformers, the rating plate gives electrical apparent power in kVA or MVA.