With the continuous improvement of voltage levels in the power system, insulation performance testing of power equipment has put forward higher requirements for testing equipment. The series resonance test device is widely used in AC withstand voltage testing of high-voltage electrical equipment such as GIS, transformers, power cables, switchgear, busbars, and generators due to its high output voltage, large test capacity, relatively light equipment weight, and low requirements for power capacity.

In the actual experimental process, the automatic tuning function is a performance that deserves special attention when selecting a variable frequency series resonance test device. Reasonably selecting equipment with automatic tuning function can not only reduce manual operation, but also improve the efficiency of finding resonance points and make the experimental process more stable.

1、 Understand the working principle of the automatic tuning function

Leseries resonance test device mainly consists of a variable frequency power supply, an excitation transformer, a resonant reactor, and a capacitive voltage divider. During the experiment, the system needs to adjust the output frequency based on the capacitance of the test object and the parameters of the reactor, so that the entire circuit reaches a series resonance state.

The automatic tuning function automatically searches for the resonant frequency through the control system and finds a suitable operating point based on the detected voltage, current, and frequency changes. After the system reaches the resonance condition, the equipment can gradually increase the voltage according to the set program to complete the subsequent withstand voltage test.

Compared to relying solely on manual frequency adjustment, automatic tuning can reduce the workload of operators repeatedly adjusting parameters and also help reduce human operational errors.

2、 Select equipment based on the type of test sample

Different power equipment has different capacitance and testing requirements, so when choosing a series resonance test device, the main test object should be clarified first.

Power cables: The length and voltage level of the cable can affect the overall capacitance, and special attention should be paid to the output capacity, tuning range, and long cable testing capability of the equipment.

GIS equipment: GIS usually has high test voltage requirements, and attention should be paid to the output voltage, resonant frequency range, and system stability of the equipment.

Transformer: The appropriate combination of reactors should be selected based on the transformer capacity, winding structure, and test voltage.

Switchgear and busbar: The appropriate equipment capacity and tuning range should be selected based on the capacitance of the test sample and the on-site test conditions.

Generator: The capacitance, rated voltage, and relevant AC withstand voltage test requirements of the generator winding should be considered.

Clarifying the test object helps to determine the voltage level, capacity, and reactor configuration required for the equipment, avoiding excessive equipment selection or inability to meet actual test requirements.

3、 Pay attention to the automatic tuning range and tuning efficiency

Automatic tuning does not mean that all devices can be adapted to test samples with different capacitance levels. When selecting, it is necessary to understand the frequency adjustment range, automatic search capability, and tuning performance under different load conditions of the equipment.

For test objects with significant changes in capacitance, it is recommended to choose equipment with a wide frequency adjustment range and flexible reactor combinations. At the same time, it should also be understood whether the device can automatically find the resonance point based on the actual load, and whether it provides corresponding prompt information when tuning fails.

Tuning efficiency is also an important reference factor. For units that require frequent on-site testing, quickly and stably completing the resonance point search can reduce preparation time and improve overall work efficiency.

4、 Check the protection function of the equipment

The series resonance test involves a high test voltage, so the protection function is directly related to equipment operation and test safety.

When selecting equipment, the following protective measures should be carefully checked:

1. Overvoltage protection: When the output voltage exceeds the set value, the system can take timely protective measures.

2. Overcurrent protection: Monitor the current of the test circuit to avoid damage to the equipment caused by abnormal currents.

3. Zero start protection: prevents the device from starting directly in a non-zero output state.

4. Disharmony protection: When the system deviates from the normal resonance state, identify the abnormality in a timely manner and take corresponding measures.

5. Flashover protection: When the test sample experiences abnormal situations such as flashover or breakdown, the equipment can respond quickly.

In addition, attention should be paid to whether the equipment has functions such as emergency stop, test status monitoring, and fault information prompt.

5、 Consider the operation mode and control system

For on-site testing personnel, the convenience of equipment operation is equally important. A series resonance test device with automatic tuning function can usually provide multiple operating modes such as automatic and manual.

Automatic mode is suitable for routine experiments, and the equipment can complete frequency search and boost operations according to the set program; Manual mode facilitates technicians to adjust relevant parameters according to special test conditions.

In terms of control system, attention can be paid to whether digital control technology is adopted, whether it supports real-time display of test parameters, recording of test data, saving of results, and report management. For users who need to conduct multiple repeated experiments, these functions can simplify the operation process and facilitate later data query and analysis.

6、 Pay attention to device configuration and after-sales service

The automatic tuning function is only a part of equipment selection, and in actual procurement, the configuration of the entire system needs to be comprehensively considered.

For example, the output capability of the variable frequency power supply, the capacity of the excitation transformer, the combination of resonant reactors, and the measurement performance of the capacitive voltage divider all need to be matched with the test requirements.

In addition, whether equipment suppliers can provide technical guidance, on-site debugging, operation training, equipment maintenance, and subsequent calibration services is also a factor that needs to be considered in the procurement process. For overseas users, it is also necessary to understand whether the device supports English operation interface, English technical materials, and remote technical support.

7、 Application of Wuhan UHV series resonance test device

Wuhan UHV Power Technology Co., Ltd. provides a frequency conversion series resonance test device, which can be configured according to different voltage levels, test capacities, and types of test objects. It is suitable for AC withstand voltage testing of power equipment such as GIS, power cables, transformers, switchgear, busbars, and generators.

The equipment adopts digital control mode, which can adjust the frequency and search for resonance points according to actual test conditions. Combined with automatic tuning, automatic boosting, and multiple protection functions, it helps users simplify the test operation process.

For power engineering companies, substations, power equipment manufacturers, and power testing institutions, selecting suitable series resonance test devices can help improve on-site testing efficiency and meet the insulation performance testing needs of different electrical equipment.

Choosing test equipment with automatic tuning function should not only focus on whether it has the function of automatically searching for resonance points, but also comprehensively consider the type of test sample, test voltage, output capacity, tuning range, protection measures, control system, and after-sales service.

For users who frequently conduct high-voltage AC withstand voltage tests, a set of frequency conversion series resonance test devices with reasonable configuration, stable tuning, and easy operation can better adapt to different on-site test conditions and provide support for insulation detection and safe operation of power equipment.