I. Overview and Working Principle of the Instrument
The winding inter-turn impulse voltage test instrument is a professional device used to test the insulation quality of windings in electrical equipment such as motors and transformers. The instrument is based on the pulse waveform comparison method as its core technical principle. During the testing process, the same high-voltage pulse is applied to the standard coil and the coil under test, causing them to generate attenuated oscillation waveforms. By comparing the overlap degree of the two sets of waveforms, it can determine whether there are faults such as inter-turn short circuits, weak insulation, corona discharge, or broken wires in the winding.
If there are inter-turn insulation defects in the winding, the electrical parameters of the winding, such as inductance, capacitance, and resistance, will change. This is manifested as deviations in the detection waveforms. By analyzing the waveform differences, the quality of the winding can be accurately determined. This instrument has strong versatility and can be used in various scenarios such as winding product production lines, equipment maintenance and repair, scientific research experiments, and quality inspections. It is a basic essential device for inter-turn insulation testing of windings.
II. Fault Types that Can Be Detected
The winding inter-turn impulse voltage test instrument can accurately identify various common faults in windings. The main fault types are as follows:
1. Inter-turn insulation breakdown
This is a common fault with a high incidence rate. The fault characteristic is that the insulation layer between windings is broken down, forming a local short circuit. This fault, if persistent, will cause local abnormal temperature rise in the winding, and in severe cases, directly burn the winding and damage the electrical equipment.
2. Corona discharge
This is an early fault phenomenon in the weakly insulated area. The insulation layer has not formed a complete breakdown path, but local discharge occurs under high-voltage conditions. Continuous corona discharge will accelerate the aging of the insulation material and shorten the service life of the electrical equipment.
3. Winding breakage
This refers to the breakage of the winding conductor. After the fault occurs, the electrical circuit of the equipment is disconnected, preventing normal startup and operation, directly resulting in equipment shutdown and failure.
4. Number difference
This is mostly caused during the winding manufacturing process. The actual number of windings does not match the design standard number, causing a deviation in the inductance of the winding, affecting the operating performance of the equipment and reducing the stability of the equipment operation.
III. Voltage Level Division of Equipment Compatibility
This instrument has a wide range of applicability and can cover various winding products of micro-motors to large high-voltage motors. According to the rated voltage of the motor and transformer, the corresponding output voltage level of the instrument is matched. The compatibility specification is as follows:
Small and medium-sized motors: Rated voltage 1140V and below, power 500kW or less, suitable for output voltage 6kV level instrument;
Conventional high-voltage motors: Rated voltage 3300V and below, suitable for output voltage 15kV level instrument;
Large high-voltage motors and power transformers: Rated voltage 10.5kV to 35kV, a 35kV level instrument must be selected, and the output energy of the instrument must not be less than 28.8 joules.
IV. Typical Application Scenarios
1. Production Line Detection of Micro-motors and Small Power Motors
This is suitable for the production inspection of small power motors such as electric tools motors, household appliance motors, and series-excited motors. It is the core equipment for quality control in the production line. This scenario mostly uses bench-top instruments, with an output voltage range of 0.3kV to 6kV, and an output energy of approximately 1.8 joules. The production line detection has the characteristics of high frequency and fast detection rhythm, and requires higher stability of waveform display and fault determination speed of the instrument. Currently, most instruments are equipped with waveform storage and automatic comparison determination functions, which can avoid errors caused by manual judgment and significantly improve the efficiency of batch detection.
2. Production and Maintenance of Small and Medium-sized Industrial Motors
For industrial motors with a rated voltage of 1140V and below and a power of 500kW or less, whether for new product factory quality inspection or quality verification after equipment maintenance, inter-turn insulation impulse tests must be conducted. This scenario uses bench-top instruments, which have forward and reverse test functions, which can improve the uneven distribution of impulse voltage in the winding and enhance the accuracy of test data.
3. Detection of High-voltage Motors and Transformers This technology is applied in the manufacturing of high-voltage motors and the maintenance of large power transformers. It is also suitable for use in mining, petrochemical and other environments with strict requirements for equipment reliability. In such scenarios, the standards for inspecting the insulation quality of windings are even more stringent. For medium and high-voltage inspections, stand-alone cabinet-type instruments are mostly used, which are compatible with high-voltage motors up to 3300V. For ultra-high voltage-level large high-voltage motors and power transformers, power-hungry cabinet-type instruments must be selected to ensure the detection energy and accuracy.
V. Inspection Precautions
The higher the motor capacity and rated voltage, the greater the output energy required by the instrument. If the instrument’s output energy is insufficient, the pulse impact depth will not meet the inspection standards, and it will be impossible to accurately detect deep and concealed insulation defects in the windings. In the conventional selection specifications, for motors with a rated voltage of 1140V, it is recommended to use a winding-to-winding impulse voltage test instrument of 6kV or higher to ensure comprehensive and accurate detection.
Post time: May-15-2026