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HV test on the three-phase induction motor is also known as
Dielectric Test
Insulation Test
Both of these
None of these
Both of these
Quick Summary: The High Voltage (HV) test, often called a High-Potential or Hi-Pot test, is a standardized diagnostic procedure performed to verify the integrity of the electrical insulation system of a three-phase induction motor. It is interchangeably referred to as a Dielectric test because it specifically evaluates the dielectric strength of the insulation against electrical breakdown under stress.
The High Voltage (HV) test, often called a High-Potential or Hi-Pot test, is a standardized diagnostic procedure performed to verify the integrity of the electrical insulation system of a three-phase induction motor. It is interchangeably referred to as a Dielectric test because it specifically evaluates the dielectric strength of the insulation against electrical breakdown under stress.
Vtest=2Vrated+1000 — Standard IS/IEC calculation for one minute power frequency withstand test voltage in Volts.
E=dVtest — Dielectric stress formula where d is the insulation thickness.
The test involves applying a voltage significantly higher than the motor's rated operating voltage between the motor windings and the frame (ground) for a specified duration (typically 60 seconds). If the insulation system is robust, the leakage current will remain within safe limits; if the dielectric material is compromised, a flashover or breakdown occurs due to an inability to withstand the electrical field intensity.
The test is mandatory for new motors after repair or installation.
It ensures the safety of operating personnel by confirming effective grounding and insulation.
Commonly performed at power frequency (50 Hz or 60 Hz).
Leakage current is monitored; an increase indicates potential insulation failure.
Identifies manufacturing defects like voids or contaminants in insulation.
Prevents catastrophic failures during actual operation under load.
Over-stressing the insulation repeatedly can lead to premature aging.
Requires high-voltage testing equipment and safety precautions.
Routine tests for three-phase induction motors.
Type testing of industrial electrical machinery.
Maintenance check after winding repairs.
The IEEE 43 standard and IS 12615 provide guidelines for insulation resistance and HV testing.
Option A and Option B represent the same testing procedure from different terminological perspectives, thus making 'Both of these' the correct choice.
C is correct — The HV test is a dielectric test used to assess the insulation integrity of the motor.
Always remember that Hi-Pot testing is non-destructive if done within specified limits, but it is considered a 'go/no-go' test for dielectric integrity.